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					                                            Physics 401
                    Physics of Ham Radio - Fall 2010
Patricia Reiff, W5TAR, Physics & Astronomy Dept, Rice U
Text: “Ham Radio License Manual” from ARRL

With help from members of….

                                                              And the VE team


        Figures in this course book are
    reproduced with the permission of the
    American Radio Relay League. This
      booklet was compiled by John P.
                Cross AB5OX
     Modified by Patricia Reiff W5TAR
                                                                                1
                                            PHYS 401 Physics of Ham Radio
              Why be a Ham?
• Radio is fun
• Radio is not expensive
• Radio is a great hobby
• You can help in disasters
• You can talk for free to
  people around the world
• New friends can help
  you get jobs
• You can help the
  community in service
  projects

                                                     2
                     PHYS 401 Physics of Ham Radio
 But isn’t a cellphone better?
• Cellphones cost per minute to use
• If you’re not within 10 miles of a highway, your
  service can be bad
• Ham can get you new friends with common
  interests
• In emergencies, cellphones are busy or not
  functional (on Sept 11, only ham communication got
  thru in New York City; in Tsunami- and hurricane-
  ravaged areas, only hams can communicate!)



                                                       3
                 PHYS 401 Physics of Ham Radio
But isn’t the internet better?
• Internet lets you leave a message when they are
  asleep. (But you can do that too with ham packets)
• Many foreign hams don’t have computers.
• Can be used while camping or sailing!
• Can be used in power outages or in emergencies
• No monthly charges
• Can be linked to computers
• Morse code is a universal language (QST)
• Meet new people with similar interests without
  dangers of chat room


                                                   4
                PHYS 401 Physics of Ham Radio
     CB’s and Family Radios
• CB’s and Family Radios allow only local communication -
  range only a few miles
• Lot of traffic on the bands… crowded and unfriendly.
• No license needed - easy to get into, but no control
  over users who hog the airwaves or make rude
  comments


                                     With a minimum
                                     “technician” ham radio
                                     license, you can talk to
                                     astronauts in space
                                     like Frank Culbertson
                                     KD5OPQ!

                                                          5
                PHYS 401 Physics of Ham Radio
     This semester‘s schedule
         Tentative: check the website frequently:
http://space.rice.edu/PHYS401/ all classes 6:15 - 9:15 pm

 •Monday Aug 23 - General introduction, Welcome to Ham radio, light
 and spectroscopy, speed of light and wavelengths (Ch 1)
 •Monday Aug 30 - Electrical principles, practical electronics (Ch 2)
 •TBD: basic circuit Lab: electrical circuits, capacitors, resistors,
 multimeters, etc.
 •Mon 9/13: Field trip to Red Cross (Sun and Space weather lecture)
 •Mon 9/20: Operating Equipment (Ch 3)
 •Sat/Sun 9/25-26: Texas QSO party
 •Mon 2/9: Communicating (Ch 4)
 •Mon 9/27: Licensing and Operating Regulations (Ch 5 & 6); Safety (ch
 7)
 •Oct 4 (tent): Midterm test (VE exam)




                                                                     6
                       PHYS 401 Physics of Ham Radio
Do you want your ham License?
We will have a special “technician” FCC ham license test, in class
(date TBD). VE’s (Volunteer Examiners) will come and give the test,
as a courtesy.

You are required to try the test. You are NOT required to pass it
(but you’d better!). If you can’t be in class that day, you can take
makeups in Tomball or at the Red Cross. (price to take the exam,
either place and each time: $15, given once a month).

Morse code test: no longer needed (but encouraged!)

General Test: Can be taken after passing the tech test. Anyone
interested? If so, we might delay the test for a week or so.
Cost: another $15.


                                                                  7
                       PHYS 401 Physics of Ham Radio
                 The Basics of Radio
                 Radio Wave Propagation
             Book, introduction; Chapters 1


   -•-• --•-
CQ means I’m Seeking You

    Figures in this course book are
  reproduced with the permission of
 the American Radio Relay League.
    This booklet was compiled by
        John P. Cross AB5OX


                                                                      8
                                      PHYS 401 Physics of Ham Radio
Frequency and Wavelength
                        •   Frequency is measured in cycles per
                            second.
                        •   The unit of frequency is Hertz (Hz)
                        •   Audio frequency is 20 Hz to 20,000
                            Hz (20 kHz)
                        •   Radio frequency is above 20,000 Hz
                            (20 kHz)
                        •   Radio frequency and wavelength are
                            related:
                             – c = f (Hz) x  (meters)
                             – c (speed of light) = 3 x 108
                                m/sec
                             –  (meters) = 300 / f (MHz)




                                                            9
       PHYS 401 Physics of Ham Radio
Electromagnetic Spectrum




                                       10
       PHYS 401 Physics of Ham Radio
Radio Spectrum




                                  11
  PHYS 401 Physics of Ham Radio
            Types of Radio Signals
• “AM”: Amplitude modulation: The strength of the signal is varied.
  (amplitude of the carrier) (600- 1500 KC is US band).
• “Short Wave”: AM at higher frequencies (2 MHz - 25 MHz). Travels
  very long distances, used for international broadcasts (e.g., BBC, Voice
  of America, mostly at night)
• “FM”: Frequency Modulation: The information is carried by changes in
  the carrier frequency. (88 - 108 MHz is FM broadcast band)
• “SSB” - Single sideband - uses a sideband of AM to reduce noise and
  increase range. Used for HF radio transmission
• “CW” - Continuous wave. The signal is on or off, and letters are sent in
  Morse Code. (“let the Morse be with you!”). Longest range. (Why?)


    •-- •- -•--         -•-• --- --- •-•• !
      W A     Y            C      O       O      L



                                                                       12
                        PHYS 401 Physics of Ham Radio
Propagation - How Signals Travel
• Radio waves travel to their destinations by three
  ways:
   – line-of-sight, typically above 30MHz. What you
     see is what you get.
   – ground-wave propagation, travels along the
     surface of the earth, even over hills.
   – Sky-wave propagation (skip), refracted back
     from the ionosphere.
• Other variations are the result of atmospheric
  phenomena and occur randomly.
• Weird things can happen - listen and learn!



                                                  13
                PHYS 401 Physics of Ham Radio
   Line-Of-Sight Propagation
• Radio signals travel in a straight line from
  transmitting to receiving antennas.
• This is the mode of propagation for VHF, UHF and
  microwave frequencies.
• FM radio and TV are also propagated in this
  manner.
• As far as antennas are concerned, the higher the
  better (limited by the curvature of the Earth).
• Direct communications with the space shuttle
  during SAREX contacts is line-of-sight.
• Reflections can also occur: they may be stronger
  than the direct signal some times. They also cause
  “picket fencing”.

                                                   14
                 PHYS 401 Physics of Ham Radio
        Repeaters Extend Range
                                                        National simplex:
                                                        146.52 MHz




NARS repeater broadcasts 146.660 MHz; listens 146.060
Repeaters have a “shift” between the frequency they listen to and
the frequency they transmit. (NARS also requires a “tone” 103.5 Hz)
                                                                            15
                        PHYS 401 Physics of Ham Radio
   Ground-Wave Propagation
• Waves follow the ground, over hills and along the
  curvature of the earth.
• This is relatively short range propagation.
• AM broadcast stations propagate by this method.
   – High end (1600 kHz) carries less than 100 miles
     during the day.
   – Low end (540 kHz) will carry about 100 miles.
• Amateur bands are higher frequency and
  propagate even less distance during the day.
• More on night time propagation later.


                                                   16
                 PHYS 401 Physics of Ham Radio
    Sky-Wave, The Cool Stuff!
• Upper atmosphere (25 to 200 miles) is where the
  Sun’s UV and X-rays strip electrons, ionizing the gas.
• The ionosphere can refract (bend) radio waves at low
  frequencies, bouncing them back.
• The determining factors for sky-wave propagation are
  the frequency in use and the degree of ionization.
• The highest frequency at which the ionosphere will
  bend radio waves is called the maximum useable
  frequency (MUF).
• When there are many sunspots, the Sun gives off
  more UV light, which results in a denser ionosphere, so
  a higher MUF!


                                                     17
                   PHYS 401 Physics of Ham Radio
              Sunspots - 11 Year cycle
       • More ionization means that MUF is higher.
       • We are currently just past the minimum of a cycle.


http://www.sec.noaa.gov/SolarCycle/




                                                                18
                                PHYS 401 Physics of Ham Radio
Sky-Wave Propagation




                                     19
     PHYS 401 Physics of Ham Radio
                  • D Region
                     • ions don’t last very long and
                       ionization reaches peak at noon.
                     • Doesn’t refract, it absorbs 160, 80
                       and 40 meters.
                  • E Region
                     • ions don’t last long, peaks at noon.
                     • can refract radio waves.
                     • maximum skip is 1250 miles.
                     • sporadic E skip works on VHF
                  • F Region
                     • most responsible for long range
                       communications.
                     • ions last a long time, some all
                       night.
                     • two regions during the day F1 and
                       F2.
                     • F2 is primarily responsible for sky-
                       wave propagation
                     • one hop is a maximum of 2500
                       miles


                                                          20
PHYS 401 Physics of Ham Radio
   Other Propagation Modes
• Scattering can be caused by the ionization trail of a meteor
  or by the atmosphere. The signals are weak and distorted.
• Tropospheric bending and ducting are caused by wide area
  temperature inversions. These bend radio waves because of
  differences in air density. This occurs in the VHF range
  (and higher sometimes).
• Amateur satellites are a popular way of communicating over
  long distances.
   – Doppler effects must be compensated for by proper
     tuning. (Higher frequency approaching, lower leaving)
   – Circularly polarized antennas help reduce fading from
     spin.
   – More power is needed (better antennas) at the horizon.
• Earth-moon-earth (EME) or moon-bounce requires high gain
  antenna arrays and lots of power.


                                                            21
                   PHYS 401 Physics of Ham Radio
International Morse Code




                                       22
       PHYS 401 Physics of Ham Radio
                            Morse Code
                             “COIN”
                            (flow chart)
                              (used by
                              railroad
                           telegraphers)



                                     23
PHYS 401 Physics of Ham Radio
                   Useful links:
Repeater directory/map/search:
http://www.artscipub.com/repeaters

Lookup of Ham by callsign:
(also practice tests, online or offline)
http://www.qrz.com/

ARRL organization (many resources, pubs):
http://www.arrl.org/

IRLP Directory (internet hop): http://status.irlp.net/index.php
 local IRLP’s: 444.300,

Echolink (from your computer or iPhone): http://www.echolink.org/
 local echolinks: 145.17 (node 5551); 443.000




                                                                    24
                        PHYS 401 Physics of Ham Radio
                         Basic Electronics

                     Chapter 2
           Basic Electrical Principles and
           the Functions of Components

   Figures in this course book are
 reproduced with the permission of
the American Radio Relay League.
   This booklet was compiled by
       John P. Cross AB5OX




                                                                     25
                                     PHYS 401 Physics of Ham Radio
  Basic Electrical Principles
• Conductors - keep loose grip on their electrons and allow
  electrons to move freely. Metals are usually good
  conductors.
• Insulators - keep close hold of their electrons and do not
  allow free movement of electrons. Glass, wood, plastic,
  mica, fiberglass and air are good insulators.
• Electromotive Force (EMF) is the force that moves
  electrons through conductors. Its unit of measure is the
  Volt. Think of it as pressure.
• Voltage Source - has two terminals (+ and -). Some
  examples are car batteries (12 volts DC), D cell batteries
  (1.5 volts DC) and a wall socket (120 volts AC).
• Current - is the flow of electrons. It is measured in
  amperes.
• Resistance (ohms, ) is the ability to oppose an electrical
  current.


                                                                26
                   PHYS 401 Physics of Ham Radio
                                27
PHYS 401 Physics of Ham Radio
      Circuit Definitions
A circuit must close to be complete!




                                           28
           PHYS 401 Physics of Ham Radio
                   Ohm’s Law
• Ohm’s Law relates Current (I), Voltage (E) and Resistance
  (R)
• The relationship can be written three ways:
              »E=IxR
              »I=E/R
              » R = E/I




                                                              29
                    PHYS 401 Physics of Ham Radio
                                30
PHYS 401 Physics of Ham Radio
                  Resistors




Mnemonic: “Black Bears Run On Young
Grass By Violets Growing Wild”
                                                31
                PHYS 401 Physics of Ham Radio
Resistor Types - Precision




                                        32
        PHYS 401 Physics of Ham Radio
Resistors - Film Type




                                     33
     PHYS 401 Physics of Ham Radio
Resistors - Variable




                                    34
    PHYS 401 Physics of Ham Radio
       Calculating Resistance




• Series:                              • Parallel:


  R=R1+R2+R3+R4                        1/R=1/R1+1/R2+1/R3
 (the voltage adds up)                 (the current adds up)

                                                               35
                    PHYS 401 Physics of Ham Radio
                  Capacitors
•   Capacitors store energy in an electric field
•   Basic unit of capacitance is the farad (f)
•   Series:        1/C=1/C1+1/C2+1/C3
•   Parallel:      C=C1+C2+C3
•   Capacitance is determined by 3 factors:
             » plate surface area
             » plate spacing
             » insulating material (dielectric)




                                                   36
                   PHYS 401 Physics of Ham Radio
Variables Determining
     Capacitance




                                     37
     PHYS 401 Physics of Ham Radio
Parallel Capacitors Increase Plate
   Area; increase charge so C




                                          38
          PHYS 401 Physics of Ham Radio
Capacitors Store Energy in
      Electric Field




                                        39
        PHYS 401 Physics of Ham Radio
Variable Capacitors




                                    40
    PHYS 401 Physics of Ham Radio
                         Inductors
• Inductors store energy in a magnetic field
    (like a little electromagnet)
•   Basic unit of inductance is the henry (h)
•   Parallel:         1/L=1/L1+1/L2+1/L3
•   Series:           L=L1+L2+L3
•   Inductance is determined by 4 factors:
                 »   number of turns
                 »   permeability of the core
                 »   cross sectional area of the core
                 »   spacing of the turns




                                                         41
                         PHYS 401 Physics of Ham Radio
Variables Determining
     Inductance




                                     42
     PHYS 401 Physics of Ham Radio
Inductors Store Energy in
     Magnetic Field

                          Current flow-->



                                       Note: current
                                       flows from + to -,
                                       but is carried by
                                       electrons which
              Electron flow-->
                                       flow from - to +



                                                     43
       PHYS 401 Physics of Ham Radio
Types of Inductors




                                    44
    PHYS 401 Physics of Ham Radio
                   Power
• Power is the rate of energy consumption.
• The basic unit of power is the watt (W)
• Power can be calculated as follows:
           »P = I x E
• Since E = I x R, you can also say:
           »P = I2 x R
• Since I = E / R, you can also say:
           »P = E2 / R

                                              45
              PHYS 401 Physics of Ham Radio
Meters - Measuring Current
                                        Ammeter
                                        must be
                                        part of the
                                        circuit to
                                        measure
                                        the current
                                        VOM -
                                        multimeter
                                        that
                                        measures E,
                                        I, R

                                                 46
        PHYS 401 Physics of Ham Radio
Meters - Measuring Voltage

                                        Voltmeter
                                        measures
                                        across the
                                        circuit (in
                                        parallel to
                                        the voltage
                                        to be
                                        measured)


                                                  47
        PHYS 401 Physics of Ham Radio
Meters - Measuring Resistance

   Ohmmeter: measures across the resistor (but
   be sure the circuit is not turned on “hot”). Puts
   in a known voltage and measures the current, so
   it requires a battery. If the circuit is
   energized, will give the wrong reading!


   Never leave a multimeter set at “ohms” - will
   run down its battery!


                                                   48
              PHYS 401 Physics of Ham Radio
Meters - Changing Range




                                      49
      PHYS 401 Physics of Ham Radio
Schematic Symbol Examples




                                        50
        PHYS 401 Physics of Ham Radio
Schematic and Block Diagrams
                         • Schematic diagrams
                           include all the
                           individual components
                           and how they are
                           connected.
                         • Block diagrams show
                           larger components
                           (black boxes) and how
                           they are connected


                                               51
         PHYS 401 Physics of Ham Radio
                                52
PHYS 401 Physics of Ham Radio
                                53
PHYS 401 Physics of Ham Radio
Amplifiers
               • Tubes and transistors
                 amplify signals applied to
                 base or control grid.
               • Transistors have
                 advantages:
                      • size
                      • power consumption
                      • cooling
                      • robustness
               • Tubes have advantages:
                      • high power




                                              54
PHYS 401 Physics of Ham Radio
                   Test Equipment
•   Voltmeter - an instrument that is used to measure voltage.
     – It is used in parallel with a circuit to be measured.
     – a series resistor extends the range of the meter.
•   Ammeter - an instrument used to measure amperage in a circuit.
     – It is hooked up in series with the circuit to be tested.
     – A shunt resistor (in parallel w/meter) extends the range of the meter.
•   Multimeter - combines the functions above with resistance and
    others to make a versatile piece of test equipment.
•   Wattmeter - a device that measures power coming from a
    transmitter through the antenna feed line. A directional
    wattmeter measures forward and reflected power. Wattmeters
    generally are useful in certain frequency ranges
•   Signal Generator - a device that produces a stable, adjustable low
    level signal (AF or RF). It can be used to tune circuits.



                                                                            55
                          PHYS 401 Physics of Ham Radio
             Emissions and SAFETY

                                      Chapter 10



   Figures in this course book are
 reproduced with the permission of
the American Radio Relay League.
   This booklet was compiled by
       John P. Cross AB5OX




                                                                     56
                                     PHYS 401 Physics of Ham Radio
               Modulation

• To transmit information we must modulate
  a radio signal. That means to vary the
  radio wave’s frequency, phase or amplitude.
• Radio frequencies can be generated by :
        – crystal oscillators
        – variable frequency oscillators



                                               57
               PHYS 401 Physics of Ham Radio
      Continuous Wave (CW)
• CW is a communications mode transmitted
  by off/on keying of an RF signal.
• The coding of the is called the
  International Morse code.
• We sometimes say “dah” for the dash and
  “dit” for the dot. A dash lasts twice as
  long as a dot.

Dit-dit-dah-dit dit-dit-dah dah-dit !


                                                58
                PHYS 401 Physics of Ham Radio
Amplitude Modulation and SSB
• At constant frequency, the power of the
  carrier is modulated in proportion to audio
  volume (pressure).
• In the frequency domain, there are upper
  and lower sidebands and the carrier
  frequency.
• Single sideband filters out all but one
  sideband. This puts more power to the
  actual modulated signal.

                                                59
               PHYS 401 Physics of Ham Radio
Amplitude Modulation and SSB




                                         60
         PHYS 401 Physics of Ham Radio
    Frequency Modulation (FM)
• The amplitude of the RF
  signal is held constant,
  but the frequency is
  varied in proportion to
  the shape of the audio
  wave.
• FM Signals are the
  cleanest. They are the
  modulation mode of
  choice for VHF and UHF
  voice communications.


                                                  61
                  PHYS 401 Physics of Ham Radio
         Spurious Emissions
• Any signal that is emitted outside the
  band on which you are operating (it’s your
  responsibility to fix it!)
• Common types include:
  – Parasitic oscillation (tube type amplifiers).
  – Removal of shields from transmitter.
  – Harmonics.
  – Splatter.
  •--- ••- -• -•- -• --- •• ••• • • ••• -••• •- -••


                                                      62
                 PHYS 401 Physics of Ham Radio
 Spurious Emissions -
        Harmonics
(multiples of a given frequency)




                                        63
        PHYS 401 Physics of Ham Radio
Harmonics Cause Interference
• Occur at definite intervals.
• Show up as interference on
  specific channels or as
  herringbone.
• Use low pass filter on
  transmitter and high pass
  on TV.
• You are responsible to
  clean up your signal.
• Can be caused by multi-
  band antennas and poorly
  tuned transmitters.




                                                    64
                    PHYS 401 Physics of Ham Radio
F is the fundamental frequency, 2 is twice that frequency, etc.
                                                                  65
                    PHYS 401 Physics of Ham Radio
Receiver (Front End) Overload
• Affects all channels, usually with dramatic
  effect.
• There is nothing that can be done to the
  transmitter, you must prevent the signal
  from entering the receiver.
• For cable systems, inspect for loose
  connections and broken shields.
• For non cable systems, use a high pass
  filter.

                                                66
               PHYS 401 Physics of Ham Radio
Spurious Emissions - Splatter
• Splatter is caused by improper adjustment
  of the transmitter resulting in
  interference with nearby frequencies.
• Sources could be:
  – talking too loud into microphone
  – microphone gain too high
  – excessive speech processing



                                                67
                PHYS 401 Physics of Ham Radio
         Signal Purity and Stuff
• Your RF can get into the power lines as well. There
  are ac power line filters which can be installed.
• You should also be careful of signal purity - stable in
  frequency and pure in tone. There are some things
  that you can readily hear.
• Key clicks are caused by rapid rise in transmitter
  output. Can cause interference several kHz on either
  side of your frequency. They can be taken out with a
  key click filter.
• Chirping is caused by transient voltage changes which
  let your frequency change slightly when keying.
• Hum - can come from poorly filtered power supplies.



                                                            68
                     PHYS 401 Physics of Ham Radio
         Emissions Standards
• Bandwidth - measure of how much space your signal takes up.
   – CW < SSB < FM
• RTTY Sending Speed
   – 28 - 50 MHz                 1200 baud
   – 50 - 222 MHz                19,600 baud
   – > 222 MHz                   56,000 baud
• RTTY Frequency Shift
   – < 50 MHz 1000 Hz
   – > 50 MHz No Limit
• Authorized Digital Bandwidth
   – 50-222 MHz        20 kHz
   – 222-450 MHz       100 kHz



                                                           69
                     PHYS 401 Physics of Ham Radio
Emission Types and Bandwidth
• CW (continuous wave) is narrowest -
  250 Hz filter is useful
• RTTY is next widest (about the same
  as CW); a 500 Hz filter is useful
• SSB has a wider bandwidth, often
  uses a 2800 Hz filter.
• FM is the widest, about 15 kHz
•- •-• • -•-- --- ••- •-• -••• •- -• -•• ••• - •• --• •••• – ?


                                                                 70
                    PHYS 401 Physics of Ham Radio
Relative Bandwidths &
   Receiver Filters




                                     71
     PHYS 401 Physics of Ham Radio
                                72
PHYS 401 Physics of Ham Radio
         Some Other Stuff
• True Forward Power = forward power reading -
  reflected power reading. This can be used to
  indicate the SWR of your antenna system.
• Marker generator - a high stability oscillator that
  produces specific frequencies which are used to
  calibrate receivers and transmitters.
• WWV and WWVH can also be used to calibrate
  receivers, as well as other things.




                                                    73
                 PHYS 401 Physics of Ham Radio
                 RF Safety
• Radio Frequency (RF) is a combination of electric and
  magnetic fields in the range of 3kHz to 300GHz.
• Non-ionizing radiation (60 Hz and RF): frequency is too
  low to ionize atoms.
• Ionizing radiation (some X-rays, gamma rays, some
  ultraviolet): frequency is high enough to ionize atoms
• Thermal effects: RF, at high enough power densities, is
  capable of heating body tissue and causing burns. It can
  even heat the eyes enough to cause cataracts and
  blindness.
• Athermal effects: evidence that magnetic fields
  (produced by RF radiation or power lines) may actually
  cause biological effects at power levels too low to cause
  heating. To date, studies are inconclusive.


                                                              74
                  PHYS 401 Physics of Ham Radio
 Thermal Effects and Safety
• Your body can absorb RF energy at certain frequencies.
   – body (adult) resonant frequency 35 MHz (grounded) or
      70 MHz (ungrounded).
   – head (adult) absorbs at 400 MHz while infants absorb
      700 MHz.
   – absorption at the body surface about 1 GHz.
• Specific Absorption Rate (SAR) describes the rate that RF
  is absorbed by the body.
• Maximum permissible exposure (MPE) is based on whole body
  SAR and explains why the safe exposure limits vary with
  frequency.
• You should avoid contact with antennas and open feed lines.
  Keep shields in place.
• RF burns can be caused by touching antennas, feedlines and
  amplifiers, design your station accordingly.


                                                           75
                    PHYS 401 Physics of Ham Radio
        Safe Exposure Levels
• IEEE developed guidelines for safe exposure levels. Have
  been adopted by ANSI.
   – averaged over a period of time, Duty cycle important.
   – controlled environments: energy levels can be determined
      and everyone on premises aware of presence of EM (e.g.
      amateur operator’s household).
   – uncontrolled environment: energy levels not known or
      persons present may or may not be aware of presence of
      EM (e.g. amateur operator’s neighbors).
• Standards are different for electric (E,V/m) and magnetic
  (H, A/m) fields. Can also be expressed in power density
  (mW/cm2).
• Cardiac pacemakers not affected, but check with doctor.



                                                           76
                    PHYS 401 Physics of Ham Radio
IEEE Standards




                                  77
  PHYS 401 Physics of Ham Radio
-••• • ••• •- ••-• • -• --- –       ••• --- •-• •-• –•-– !
                                                             78
                PHYS 401 Physics of Ham Radio
   FCC Exposure Regulations
• Controls exposure to RF fields, not strength of RF
  fields.
• Depends on environment being controlled or
  uncontrolled.
• Requires all amateur stations be evaluated.
   – actual measurements or calculations
   – use of tables
• Some stations exempted: <50 W PEP, HTs and
  vehicle mounted radios with PTT button.
• These stations still have to comply with the MPE
  limits.
• Most stations are already in compliance.


                                                   79
                 PHYS 401 Physics of Ham Radio
FCC Exposure Regulations (cont’d)
• FCC has a bulletin that contains charts and tables
  to estimate compliance:
       • OET Bulletin 65: Evaluating Compliance with
         FCC-Specified Guidelines for Human
         Exposure to Radio Frequency Radiation.
• FCC does not require records, but could be useful
  if the FCC asks.
• You will indicate that you know and understand the
  regulations when you fill out the Form 610 for you
  license examination.


                                                   80
                 PHYS 401 Physics of Ham Radio
                                81
PHYS 401 Physics of Ham Radio
 Determining Field Strengths Around Antennas

• Field strength meters have an antenna which can cause
  mutual coupling with the transmitting antenna resulting in an
  altered radiation pattern. This can happen in the reactive
  near (induction) field.
• The reactive near field is considered to be about one half
  wavelength from the radiating center of a wire antenna.
• In the radiating near field conductors can alter the
  radiation pattern. There could be “hot spots” you can’t find
  with a meter.
• The radiating far field forms the traveling RF wave with an
  E and H component.
   – E/H = 337 (intrinsic impedance of free space)
• In the far field, field strength follow the inverse square law.


                                                               82
                     PHYS 401 Physics of Ham Radio
                                • This table is used to
                                  determine exposure
                                  limits based on actual
                                  measurements or field
                                  strength calculations.

                                • Requires calibrated
                                  field strength meter to
                                  make the
                                  measurements.

                                • Note the difference in
                                  averaging time and the
                                  requirement to use
                                  power density above
                                  300 MHz.




                                                            83
PHYS 401 Physics of Ham Radio
         Evaluations by Tables
• Tables are set up to evaluate
  stations with commonly used
  antennas and frequencies.
• Note that there is a difference
  in exposure for controlled and
  uncontrolled environments.
• Generally, distance to the
  limit increases with
  frequency, power and antenna
  gain.
• These tables are the most
  commonly used method by
  amateurs.

                                                         84
                         PHYS 401 Physics of Ham Radio
                       • Another method for
                         evaluation is to use
                         graphs such as this one.


                       • Any value of effective
                         radiated power, which
                         takes into account
                         antenna performance,
                         can be found on the
                         graph and be used to
                         compare to MPE tables.




                                                    85
PHYS 401 Physics of Ham Radio
  Steps to Limit RF Exposure
• Reduce power
• Locate antennas more distant from areas of
  controlled and uncontrolled exposure.
• Reduce transmitting times within a 6 minute
  (uncontrolled) or 30 minute (controlled) period.
• Select a low duty cycle (ratio of average power to
  PEP) operating mode
   – FM=PM=RTTY>CW>SSB
• Select an antenna the reduces exposure and orient
  it properly.

                                                  86
                 PHYS 401 Physics of Ham Radio
Unauthorized Use - Safety Tips
 • To protect your station from unauthorized use you
   could:
    – install a key lock on your power supply
    – remove microphone from your mobile rig.
 • Be certain that you have a good ground, that your
   equipment is all grounded and ground all antennas
   when not in use.
 • RF exposure can cause damage to your body - so
   be careful. Keep antennas away from people. 1270
   MHz can cause damage to eyes.
 • Do not defeat interlocks - they protect you from
   high voltage, especially in power amplifiers.


                                                  87
                 PHYS 401 Physics of Ham Radio
      Electrical Wiring Safety
• Three conductor wiring systems (common in most houses):
   – hot - black or red - this one should have the fuse. It also
     will have a connection to the brass screw in a lamp socket
     or switch.
   – neutral - this one goes to the unfused side of a
     transformer primary. In a switch or socket, attach it to
     the white screw
   – Ground - green or bare copper - connect this to the
     chassis ground or to the green screw in a switch or socket.
• National Electrical Code provides limits for safety in power
  wiring and antennas.
• Low levels of electricity (30 volts, 0.1 ampere) could be fatal.
  The brain is the most susceptible organ in the body.
• If you have to mess with live wires, keep one hand behind
  your back, make sure power supply switch is easily accessible,
  make sure others know where fuse box main breaker is.


                                                                 88
                      PHYS 401 Physics of Ham Radio
Household Wiring




                                   89
   PHYS 401 Physics of Ham Radio
   ARRL Safety Code - Part 1
• Unplug everything you plan to work on before touching
  anything behind or inside the radio.
• Never let anyone turn the power on and off for you when
  you’re working on a radio.
• Don’t work on a radio when you’re tired or sleepy. Don’t work
  alone.
• Never adjust internal electrical components by hand - use
  the proper plastic or insulated tools. Be sure the insulation
  is in good condition.
• Don’t touch grounded metal (like radiators or water pipes) or
  wet floors when you’re working on radio equipment. You can
  get a dangerous shock even if the equipment is grounded,
  through “ground loops” between different ground points.




                                                             90
                    PHYS 401 Physics of Ham Radio
  ARRL Safety Code - Part 2
• Never wear headphones when working on radios.
• Always keep one hand in your pocket when working
  on radios. That way, if you do touch a “hot” point,
  the electricity cannot travel across your chest and
  cause a heart attack.
• Tell your family how to turn the power off and how
  to give artificial respiration. Be sure you are up to
  date in first aid.
• Develop your own safety techniques. Take the
  time to be careful, death is permanent.


                                                     91
                 PHYS 401 Physics of Ham Radio
         Operating a Ham Station

               Chapter 1, Chapters 4-6
              Transmitters and Receivers
                 Antennas & Feedlines

   Figures in this course book are
 reproduced with the permission of
the American Radio Relay League.
   This booklet was compiled by
       John P. Cross AB5OX




                                                                     92
                                     PHYS 401 Physics of Ham Radio
Typical Amateur Station Layout




                                         93
         PHYS 401 Physics of Ham Radio
Typical Amateur Packet Station




                                          94
          PHYS 401 Physics of Ham Radio
CW Transmitters are the Simplest




                                           95
           PHYS 401 Physics of Ham Radio
Block Diagram of FM
    Transmitter




                                    96
    PHYS 401 Physics of Ham Radio
Schematic of FM transmitter




                                        97
        PHYS 401 Physics of Ham Radio
              Receivers
• Radio receivers demodulate the signal - they
  retrieve the information from the RF wave.
• Receivers convert radio signals into audio
  signals.
• The heart of the receiver is the detector.
• Modern receivers are very sensitive and
  very complex - use feedback to increase
  signal strength


                                              98
              PHYS 401 Physics of Ham Radio
Simple AM Crystal Set




                                     99
     PHYS 401 Physics of Ham Radio
Superheterodyne Receiver




                                       100
       PHYS 401 Physics of Ham Radio
Low Pass Filter




                                  101
  PHYS 401 Physics of Ham Radio
High Pass Filter




                                  102
  PHYS 401 Physics of Ham Radio
Band Pass Filter




                                   103
   PHYS 401 Physics of Ham Radio
CW Receiver




                                 104
 PHYS 401 Physics of Ham Radio
AM Receiver




                                 105
 PHYS 401 Physics of Ham Radio
FM Receiver




                                 106
 PHYS 401 Physics of Ham Radio
Data Modes




                                107
PHYS 401 Physics of Ham Radio
               Antennas & Feed lines

                        (Chapter 8.13 to end)



   Figures in this course book are
 reproduced with the permission of
the American Radio Relay League.
   This booklet was compiled by
       John P. Cross AB5OX




                                                                     108
                                     PHYS 401 Physics of Ham Radio
         Antennas - General
            Information
• We convert electrical current into radio waves
  with an antenna.
• The purpose of the antenna is to radiate the
  energy, propagate the radio wave.
• When receiving, the antenna converts a radio wave
  into an electrical current.
• A good antenna is worth more than a big amplifier!
• It pays also to have good, clean connections to
  prevent power losses.



                                                  109
                 PHYS 401 Physics of Ham Radio
  Transmission or Feed Lines
• Special cables or wires that connect the
  transceiver to the antenna.
• Feed lines, like antennas, have a
  characteristic impedance which needs to
  be matched to the transceiver and antenna.
• Matching devices are used to adapt one
  impedance to another.
• Coaxial cable and parallel conductor (twin
  lead) are the two most common feed lines.

                                              110
              PHYS 401 Physics of Ham Radio
Coaxial Cable
            • Impedance 50 : RG-58, RG-8
              RG-213
            • Impedance 72 : RG-59 RG-11
            • Thick cable (RG-8, RG-11) and
              good shielding reduces losses.
            • Advantages are:
               – weather resistance
               – it can be buried
               – it can be bent or coiled
               – it can be next to metal
               – impedance matches most
                 antennas.
            • Disadvantage is cost.



                                           111
 PHYS 401 Physics of Ham Radio
Twin Lead (ladder line)
                  • Impedance is 300-450 
                  • Major advantage is low losses
                    (can have a long run).
                  • Disadvantages are:
                       – cannot be coiled.
                       – cannot be run near metal.
                       – impedance doesn’t match modern
                         transmitters.
                       – Limited to less than 30 MHz




                                                112
      PHYS 401 Physics of Ham Radio
Cable Attenuation




                                   113
   PHYS 401 Physics of Ham Radio
   Connectors are Important
• BNC connectors are compact, often used for hand held
  radios
   – designed for use with RG-58
   – low loss, quick connect.
• PL-259/SO-259 commonly used for HF and VHF applications.
• N-Type, designed for RG-213 and RG-8,
   – low loss
   – used for UHF applications
• Good soldering technique and careful construction are
  critical to making good connections of cable to connectors.




                                                          114
                   PHYS 401 Physics of Ham Radio
        Impedance Matching
• Devices are networks of capacitors and inductors.
• Transmatch is a device that has adjustable
  characteristics so it can be used on several bands.
• SWR (standing wave ratio) meter is used to
  measure impedance matching. It is connected
  between the transmitter and the transmatch.
• A balun (balanced to unbalanced) is a device to
  couple a balanced load to an unbalanced load.
• Balanced: e.g.twin lead, dipoles, neither side to
  ground.
• Unbalanced: e.g.coax and verticals, one side to
  ground.

                                                   115
                 PHYS 401 Physics of Ham Radio
Impedance Matching Hookup




                                        116
        PHYS 401 Physics of Ham Radio
 Standing Wave Ratio (SWR)
• Ideally, all the forward power from the
  transmitter should be emitted by the antenna, if
  the impedances are matched.
• We want all the forward power to radiate from
  the antenna and none of it to be reflected.
• SWR is the ratio of the maximum voltage on the
  line to the minimum, ideally, 1:1.
• SWR of less than 2 is acceptable. Higher than 4
  indicates a problem.
• Modern transmitters are designed to match a 52
   load.
• Good matching improves performance!


                                                     117
                 PHYS 401 Physics of Ham Radio
                   SWR Meters
• Used to measure impedance matching of transmitter
  and feed line and the resonant frequency of an
  antenna.
• Need to determine frequencies the meter was
  designed for. Outside that range they will not be
  accurate.
• Problems with antennas can be found with the SWR
  meter:
   – erratic measurements could indicate loose connections.
   – extremely high could indicate shorts or gross dimension
     problems
   – change with time (months) could indicate corrosion.
• Tuning an antenna is probably the most common use.


                                                               118
                      PHYS 401 Physics of Ham Radio
  Half-Wave Dipole Antenna
• The length of the half-
  wave dipole is
  calculated by:
   1/2(ft)=468/f(MHz)
   1/4(ft)=234/f(MHz)
• This is only
  accurate for
  frequencies up to
  30 MHz (10 meters)


                                                 119
                 PHYS 401 Physics of Ham Radio
                 Dipole Stuff
• Insulators are needed for the center and the ends. Can be
  bought (cheap) or can be home-brewed from plastic.
• Wire choice is important. Best is copper clad steel. 12-14
  gauge is suitable. Small gauge wire will will stretch.
• Cut wires a little longer than calculated to allow for
  connections and to allow fine tuning.
• Use good coax with >95% shielding. RG-58 works just fine
  for runs up to about 100 feet.
• Dipoles radiate most perpendicular to the wire. Alignment
  may be important.
• Get it as high as you can. Preferable 1/2 above ground.
• Inverted V and slopers work just fine.


                                                           120
                    PHYS 401 Physics of Ham Radio
         More Dipole Stuff
• Use your imagination to get lines into trees. Bow
  and arrow, rocks and slingshots work well. Send up
  a light line, then pull through the support ropes.
• Don’t use polypropylene line; it deteriorates.
  Nylon is better, and dacron is best.
• If you can, support the middle as well as the ends,
  it makes for a sturdier installation.
• Make sure your antenna is a long way from metal
  things, flag poles, gutters, etc.
• NEVER NEVER put your antenna near power lines.


                                                   121
                 PHYS 401 Physics of Ham Radio
  Tuning with an SWR Meter
• Install SWR meter at
  antenna feed point.
• Set transmitter to low
  power.
• Adjust meter and take
  series of
  measurements across
  frequency band.
• A “dip” indicates the
  resonant frequency
  (lowest is best!).

                                                122
                PHYS 401 Physics of Ham Radio
    More Tuning With a SWR
• If there is no dip, you must
  look at the slope of the
  SWR curve. It slopes down
  toward the resonant
  frequency.
• If the minimum is at the
  low frequency end, the
  antenna is too long.
• If the minimum is at the
  high frequency end, the
  antenna is too short (so
  make them a little long to
  start!!)


                                                    123
                    PHYS 401 Physics of Ham Radio
           Multi-Band Dipoles
• A simple three band dipole
  can be built from ladder
  line in a manner similar the
  the simple dipole.
• Advantage is that a single
  antenna can be used on
  several bands.
• You will need a transmatch.
• Be careful, this kind of
  antenna can radiate on
  several wavelengths. Be
  sure your transmitter is
  properly adjusted.

                                                    124
                    PHYS 401 Physics of Ham Radio
        Quarter-Wave Vertical
• This is an unbalanced antenna,
  one side is grounded.
• Omni-directional that tends to
  shoot signals toward horizon.
• Radiator is 1/4 = 234/f(MHz).
• This is accurate for < 30MHz,
  end effects and radiator
  diameter to frequency ratio
  make it overestimate for higher
  frequencies
• Connect center conductor to
  radiator and shield to ground.




                                                     125
                     PHYS 401 Physics of Ham Radio
  Ground Plane Antenna
Easy to build, good outdoors (and indoors)




                                             126
            PHYS 401 Physics of Ham Radio
               Beam Antennas
• Directional antennas which provide a lot of gain in the
  direction pointed.
• Driven element is 1/2 , making it impractical for 80 and 40
  meters.




                                                             127
                    PHYS 401 Physics of Ham Radio
Antenna Polarization
                    • Polarization: Direction of
                      the electric force lines in
                      a radio wave
                    • Vertical antennas are
                      vertically polarized
                    • Dipoles are horizontally
                      polarized.
                    • Best results are obtained
                      with transmitting and
                      receiving antennas having
                      same polarization.




                                                    128
     PHYS 401 Physics of Ham Radio
Cubical Quad and Delta Loop




                                        129
        PHYS 401 Physics of Ham Radio
          Other Antennas
• Handy Talkies often use a “rubber duck.”
  This design is compact, but a compromise
  design. Lower performance.
• Better performance can be had with 1/4
  and 5/8  telescoping antennas.
• Roof mounted 5/8  antenna has better
  gain than the others. Car roof is a great
  ground plane!


                                              130
              PHYS 401 Physics of Ham Radio
           Repeater Overview
• Simplex operation- two stations are talking directly on the
  same frequency.
• Duplex operation - two stations communicating transmitting
  and receiving on different frequencies.
• Repeater operations - use standard frequency offsets from
  the receiving mode. This is automated in most VHF and UHF
  equipment.
• There is a listing of all amateur repeaters which can be used
  to find useful frequencies. Many repeaters have special
  features.
• Repeater frequencies are mostly coordinated to minimize
  overlap and possible interference.
• Most repeaters are “open”, anyone can use them.
• Often incorporate CTCSS or PL tones to avoid interference.



                                                             131
                    PHYS 401 Physics of Ham Radio
       Repeater Operations
• Don’t call CQ on a repeater, simply say: “AB5OX
  listening”
• To join a conversation simply say your call sign
  during a break and wait to be acknowledged.
• “Break” means that you have emergency traffic,
  don’t use it unless you need it.
• Most repeaters have a courtesy beep which
  indicates that the transmitting station has
  released the PTT.
• Most repeaters also have a time out feature to
  protect the transmitter.
• Be Courteous, it’s more fun that way.

                                                     132
                 PHYS 401 Physics of Ham Radio
CW (Morse Code) Operations
• Listen before transmitting “QRL?”
• Send at a speed that you can easily read.
• Calling CQ, use the “3 X 3” call:
   – CQ CQ CQ DE AB5OX AB5OX AB5OX K
• To answer, use “2 X 2” format:
   – AB5OX AB5OX DE K5CXH K5CXH AR
• Use appropriate prosigns, Q signals and abbreviations:
   – K5CXH DE AB5OX BT TNX FOR CALL BT UR RST 559
      BT NAME JOHN QTH CAMP STRAKE NR HOUSTON BK
• Close the conversation as follows:
   – TNX QSO ES 73 BT CUAGN K5CXH DE AB5OX SK



                                                     133
                 PHYS 401 Physics of Ham Radio
                                134
PHYS 401 Physics of Ham Radio
Common Prosigns




                                   135
   PHYS 401 Physics of Ham Radio
                                136
PHYS 401 Physics of Ham Radio
Single Sideband (SSB) Operations
• Voice communications are known as “phone”: SSB, AM,
  FM.
• SSB is the most common phone mode on HF.
• Initiate a contact with “3 X 3” call as with CW, but
  use phonetics for your call sign.
• Reply with the calling station’s call sign, this is , then
  your call phonetically.
• Keep your conversation plain and simple. Be courteous.
• Don’t use prosigns or Q signals and don’t use CB
  jargon.
• Signal reports are only “RS”.
• Listen before you talk, use VOX or PTT and listen to
  make sure you are not doubling.

                                                         137
                    PHYS 401 Physics of Ham Radio
      Data Emissions - RTTY
• RTTY - Radio Teletype , narrow band direct printing
  telegraphy - continuous signal modulated between
  two frequencies.
   – FSK - frequency shift keying - CW carrier shifted 170Hz
     (HF)
   – ASFK - audio-frequency shift keying - shifting audio tone
     transmitted by FM (VHF). MCW (modified CW).
• Only 1 QSO can be maintained on a given frequency
  and it requires operator control of transmissions.
• Modern systems use computers and modems.
• Baud rates are typically 300 (HF) and up to 1200
  (VHF).
• Call CQ with the “3-6 X 3” method.
• Use prosigns and Q signals.


                                                           138
                   PHYS 401 Physics of Ham Radio
     Data Emissions - Packet
• Highly efficient and error-free due to the
  protocol.
• Used TCP/IP - transmission control protocol /
  internet protocol (the one used by the internet).
• System is controlled with a computer and a
  terminal node controller (TNC). The TNC controls
  transmissions.
• Connections are made and maintained during a
  “connect.” Multiple connections can be maintained
  on a given frequency.
• Automated message forwarding and storage are
  quite common.

                                                 139
                PHYS 401 Physics of Ham Radio
                           FCC Regulations

                                         Jim Kirk
                                          KJ5X


   Figures in this course book are
 reproduced with the permission of
the American Radio Relay League.
   This booklet was compiled by
       John P. Cross AB5OX




                                                                     140
                                     PHYS 401 Physics of Ham Radio
        The Amateur Service
• Amateur Operator - a person holding a valid license to operate an amateur
  station.
• Amateur Station - A station licensed in the amateur service, including the
  apparatus necessary for carrying on radiocommunications.
• Amateur Radio License - includes an operator license and a station license.
   – FCC (Gettysburg PA) issues licenses.
   – Class of license determines frequency privileges
   – novice, technician, general, advanced, amateur extra.
   – Must have original or copy to operate.
   – Good for 10 years - renew with form 610 (2 year grace period).
• Control Operator - amateur operator designated by the licensee of a
  station to be responsible for the transmissions from that station to assure
  compliance with the FCC rules. Operate only to privileges of control
  operator. Responsibility joint between control operator and station
  licensee.



                                                                           141
                         PHYS 401 Physics of Ham Radio
Five Principles of Amateur Radio
  • Recognition and enhancement of the value of the amateur
    service to the public as a voluntary non commercial
    communication service, particularly with respect to
    providing emergency communications.
  • Continuation and extension of the amateur's ability to
    contribute to the advancement of the radio art.
  • Encouragement and improvement of the amateur service
    through rules which provide for advancing skills in both the
    communications and technical phases of the art.
  • Expansion of the existing reservoir within the amateur
    radio service of trained operators, technicians and
    electronics experts.
  • Continuation and extension of the amateur's unique ability
    to enhance international goodwill.


                                                              142
                     PHYS 401 Physics of Ham Radio
                                143
PHYS 401 Physics of Ham Radio
                                144
PHYS 401 Physics of Ham Radio
             Amateur Licenses
Class          Tests                  Privileges
Technician     Basic theory and       All amateur privileges above
               regulations            50.0 MHz
               (Element 2)
Technician     5 wpm code             All "novice" HF plus
with Morse     (Element 1)            technician
code privileges
(Tech – plus)
General         Elements 1,2 and 3    All privileges except those
                                      reserved for Amateur Extra
Amateur Extra Elements 1,2,3 and      All amateur privileges.
              4


                                                                     145
                    PHYS 401 Physics of Ham Radio
Electromagnetic Spectrum




                                       146
       PHYS 401 Physics of Ham Radio
                                147
PHYS 401 Physics of Ham Radio
            Power Limitations
• Transmitter Power:1500 Watts PEP maximum
  except:
   –   200 watts PEP on all novice sub-bands
   –   200 watts PEP on 30 meters
   –   100 watts PEP for beacon stations
   –   Novices 25 watts PEP 222.1-223.91 MHz
   –   Novice 5 watts PEP 1270-1295 MHz
• PEP (peak envelope power) - the average power
  supplied to the antenna transmission line by a
  transmitter during one RF cycle at the crest of
  modulation. Transmitter power is measured at the
  antenna terminals of the transmitter or amplifier.


                                                   148
                   PHYS 401 Physics of Ham Radio
    On The Air Activities
•   Relaying Messages
•   Ragchewing
•   DX (long distance communications)
•   Collecting Awards and Certificates
•   Contesting
•   Community Service
•   Emergency Communications


                                           149
           PHYS 401 Physics of Ham Radio
Use of Phonetic Alphabet
Improves Understanding




                                       150
       PHYS 401 Physics of Ham Radio
       Operating Guidelines
• Valid US call signs begin with A, K, N, W, Number depends
  on call district (NYT, page 2-16)
• Unidentified communications or signals prohibited. ID
  every 10 minutes and at end of conversation. For third
  party in foreign country you have to use both call signs at
  end of conversation.
• Broadcasting is prohibited; so is malicious (harmful)
  interference, false or deceptive signals
• Third party communications allowed in US and countries
  with third party agreements.
• Amateur Communications is noncommercial radio
  communication between amateur stations, solely with a
  personal aim and without pecuniary or business interest.


                                                            151
                   PHYS 401 Physics of Ham Radio
                                152
PHYS 401 Physics of Ham Radio
 More Information About Operations
• An amateur station must use the minimum power
  necessary to carry out the desired conversation.
• Test emissions (unmodulated carrier) should be
  minimized, use a dummy load
• Secondary service (e.g.450 MHz) - a station in
  secondary service must not cause harmful
  interference to stations in primary service and
  must accept interference from stations in primary
  service.
• Repeater - Station that automatically re-transmits
  the signals of other stations.
• FCC rules in favor of coordinated repeaters.
  Uncoordinated repeater is responsible for solving
  the interference problem.

                                                   153
                 PHYS 401 Physics of Ham Radio
Emergency Communications

• FCC recognizes that "amateurs may provide essential
  communications in connection with the immediate safety of
  human life and immediate protection of property when
  normal communications systems are not available."
• Operations in emergency situations may be outside the
  person’s license privileges.
• RACES (Radio Amateur Civil Emergency Service) - must be
  registered with responsible civil defense organization to
  operate a RACES station. Rules permit tests and drills for
  one hour per week.
• Tactical call signs ("command post" or "ambulance control")
  promote efficiency. They do not fulfill ID requirements,
  however.

                                                           154
                   PHYS 401 Physics of Ham Radio
           More Regulations
•   Telecommand of Model Craft - transmitter must have
    station's call sign and licensee's name and address.
    Maximum power is one watt.

•   Prohibited Transmissions:
       – accepting direct or indirect payment for operating an
         amateur station.
       – broadcasting.
       – news gathering
       – transmitting music.
       – aiding criminal activities.
       – transmitting codes and ciphers.
       – engaging in obscenity, profanity or indecency.




                                                                 155
                   PHYS 401 Physics of Ham Radio
        A Radio in space - IMAGE
•   Space’s longest dipole antenna - 500 m tip to tip!
•   Crossed dipoles, plus a spin axis antenna allow
    direction finding.
•   Sounding of remote regions is like “radar”.
       – Can get doppler information (motion of target)
       – Bounces off the plasma regions of the
         magnetosphere
       – (like a skywave bounces off the ionosphere)
•   Crossed dipoles, plus a spin axis antenna allow  http://image.gsfc.nasa.gov/
    direction finding of the return signals
•   “Space Weather” CD has information, and links to
    realtime data.
•   Listen to the sounds of space!
    http://image.gsfc.nasa.gov/poetry/inspire/



                                                                        156
                            PHYS 401 Physics of Ham Radio
A Radio in space - IMAGE




                                       157
       PHYS 401 Physics of Ham Radio
                                158
PHYS 401 Physics of Ham Radio

				
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