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					Computer-Aided Design of Complex Waveguide
Filters for Space Communication Systems
J. V. Morro, C. Bachiller, H. Esteban, V. E. Boria
Instituto de Telecomunicaciones y Aplicaciones Multimedia (iTEAM)
Universidad Politécnica de Valencia
Building 8G, access D, Camino de Vera s/n 46022 Valencia (SPAIN)
Corresponding author:

                                       Abstract                             risk of radiofrequency breakdown decreases. Mo-
                                                                            reover, if the dielectric posts are circular the ma-
                    This paper presents a case study of advanced op-        nufacturing effort is dramatically reduced com-
                    timization techniques for the automated design          pared to square shapes. However, the accurate
                    of complex waveguide filters for space appli-           modeling of the circular dielectric resonators is far
                    cation, and a detailed study of the multipactor         more complex than for square ones, since circu-
                    effect in different H-plane waveguide filters: all      lar and rectangular geometries must be analyzed
                    metallic, loaded with dielectric cylinders and          together. Other drawback to the use of dielectric
                    evanescent mode.                                        loading materials in the filters is the increase of
                                                                            loss level due to the dielectric tangent factor.
                    Keywords:multipactor, waveguide filters, dielec-
                    tric cylinders, space communications, computer          This paper begins with a case study of advan-
                    aided design, optimization, aggressive space            ced optimization techniques for the automated
                    mapping, segmentation, hybridization, genetic           design of complex waveguide filters for space
                    algorithms                                              applications. The accurate design of electromag-
                                                                            netic (EM) structures requires a tradeoff between
                                  1. Introduction                           accuracy and computation time. When designing
                                                                            complex structures, the use of a very accurate si-
                    There are many reasons that lead to develop new         mulation tool can be unaffordable. The Aggressive
                    topologies of high frequency filters for space          Space Mapping (ASM) methodologies address this
                    applications, i.e: reduction of mass and volume,        issue. Aggressive Space mapping [3] can be used
                    increase of thermal stability for high power appli-     to reduce the computational burden by using two
                    cations, increase of out-of-band rejection, reduc-      different simulation tools of different accuracy
                    tion of manufacturing effort, availability of analy-    and efficiency: an efficient but not very accura-
                    sis and design tools for synthesizing a desired         te tool (coarse model) in the optimization space
                    response and reduction of risk of radiofrequency        (OS), and an accurate but not very efficient tool
                    breakdown (i.e. Multipactor effect [1], [2]).           (fine model) in the validation space (VS). These
                                                                            methodologies move the computational burden
                    Rectangular waveguide H-plane filters are one of        to the OS, thus reducing the overall computation
                    the most popular technologies for implementing          time, while the accuracy is still guaranteed by the
                    satellite communications filters, and many efforts      use of the fine model. Although ASM has proved
                    are being devoted to improve their capabilities. The    to be very useful for EM design, there is still much
                    development of new topologies in this technology        research dedicated to improve the robustness
                    has been historically limited by the availability of    and performance of ASM [4]. As an alternative to
                    CAD tools that allow implementing a filter with a       those extensions of ASM, we proposed to improve
                    required response and several predefined improve-       the ASM approach by using a segmentation and
                    ments in terms of mass, stability or high power ef-     hybridization strategy. The speed and robustness
                    fects (i.e. multipactor). An efficient Computer-Aided   of the optimization process can be greatly impro-
                    Design (CAD) software package requires a fast and       ved by decomposing the structure as proposed in
                    accurate analysis tool for the selected topology        [5] and [6]. Moreover, the design process can still
                    and a reliable optimization strategy.                   be improved by using a suitable combination of
                                                                            several optimization algorithms instead of using
                    The topologies that are analyzed and designed in        a single all-purpose technique such as a genetic
                    this work are rectangular waveguide H-plane fil-        algorithm. In this paper, the completely automa-
                    ters loaded with cylindrical dielectric posts. When     ted CAD tool recently proposed in [7], which does
                    introducing these elements in the filter, the mass      not require human intervention, is adapted for the
                    and volume are reduced, the thermal stability and       accurate design of several complex waveguide
                    the out-of-band rejection are increased, and the        filters: H-plane coupled cavities filters with and

106                                                                              ISSN 1889-8297 / Waves      · 2009 · year 1
without tuning elements, and novel designs with
dielectric resonators.

Then, this work presents the results for the multi-
pactor effect in the different topologies of filters
designed, i.e all metallic ones, filters loaded with
circular dielectric posts and evanescent mode fil-         Table 4. Types of filters considered in this work.
ters loaded with dielectric posts (see Fig. 1). The
study has been made on the basis of a multimodal
analysis method [8] that enables the computation         ŋ near zero. At each iteration j, the next point is
of the electromagnetic fields inside the filter and      found by a quasi-Newton iteration:
the dielectric posts in a very accurate and efficient
way. The results for such electromagnetic fields
have been successfully compared to results ob-
tained with a commercial simulator (Ansoft HFSS                                                          1.2
[9]). Then a comparative study of the multipactor
effect that can appear between the two metallic          where x(0) = x* and h(j) solves the linear system:
                                                                em     os

surfaces of each filter has been performed. In order
to achieve a fair comparison, the study was made                             B(j)•h(j)=-f(j)
on several filters with the same frequency respon-                                                       1.3
se. The filters loaded with dielectric posts are sma-
ller than all the metallic ones, and some of them        B(j) is an approximation to the Jacobian matrix
have also a better out-of-band rejection behavior.       and is obtained from B(j-1) using the Broyden up-
Considering the multipactor discharge, the study         date [3].
concludes that the dielectric posts concentrate the
electric field inside them, thus producing a smaller
level of electromagnetic field outside the dielectric    3. Aggressive Space Mapping with
posts than for the all-metallic filters. Following the   Segmentation and Hybridization
premise that the multipactor discharge can only
appear between the metallic surfaces of the filter,      Segmentation
the dielectric loaded filters can handle more power      In [4] and [10], a segmentation strategy was pro-
without risk of multipactor breakdown.                   posed for the design of some filter structures,
                                                         such as H-plane coupled cavity filters composed
                                                         of N resonant cavities and N+1 coupling win-
   2. Aggressive Space Mapping                           dows. This segmentation technique transforms
             Method                                      a slow multidimensional design process into
                                                         several efficient and robust design steps, whe-
The original ASM strategy describes the beha-            re a small number of parameters are designed
vior of a system by means of two spaces models:          at the same time. However, there is the risk that
the optimization space (OS), denoted by Xos, and         the coupling among all cavities (not just among
the validation space (VS), denoted by Xem. We            adjacent cavities) is not properly taken into ac-
represent the designable model parameters in             count. To solve this problem, the segmentation
these spaces by the vectors Xos and Xem, respec-         strategy proposed in [11] adds new steps to the
tively. The objective of the ASM procedure is to         original strategy. The resulting new segmenta-
find the optimum point Xem in VS that minimizes          tion strategy designs the filter through the steps
the following non-linear function:                       summarized in Table I.

                  f(xem )=P(xem )-x*os                   The Ordinary step designs the parameters rela-
                                                         ted to cavity i simulating the i first cavities, and
                                                  1.3    using for the rest of parameters of the i-1 first
                                                         cavities the values obtained in former iterations.
where X*os is the optimum point in OS and P(xem )        The error function is computed comparing the
is the point in OS that satisfies Rf(xem )=Rc(P(xem)),   response of the i first cavities with the ideal res-
Rf and Rc being the vectors with the responses of        ponse. The ideal response of the i first cavities is
the fine and coarse models. The ASM procedure            obtained using the first i resonators of the proto-
finishes when ||f(xem )|| is below some threshold        type composed of impedance inverters and half-

  Table 1. Steps of the proposed segmentation design strategy.

Waves · 2009 · year 1 / ISSN 1889-8297                                                                          107
                  wavelength transmission lines. The Coupling              the filter, independently of the frequency value.
 Both the         step adjusts, every three cavities, all the design       The input threshold power is also a function of
                  parameters of the cavities previously designed,          the frequency and can be calculated by using
                  thus achieving the required small changes in             the VMFmax, the characteristic impedance Z0
 and robust-      the values of the parameters due to couplings            and the threshold voltage Vmulti that enables
 ness can be      among cavities. The Central Cavity step designs          the multipactor breakdown. This value can be
 drastically      the dimensions of the central cavity simulating          obtained by using Multipactor Calculator [14]
 improved         the whole filter structure, and the Final step re-       and depends on the type of metallic surface and
 when a           fines the design taking into account all possible        the frequency-gap product.
 suitable         interactions among cavities.
 of optimi-       Hybrid Optimization
 zation algo-     Both the efficiency and robustness of the opti-                                                            1.4
 rithms is used   mization process can be drastically improved
                  when a suitable combination of optimization
                  algorithms is used instead of a single algorithm.
                  If only a gradient method is used, it may fail to                                                          1.5
                  reach the optimum if the starting point is far
                  from it. On the other hand, the use of a robust          The minimum of this equation in the whole
                  method such as the simplex method or genetic             frequency band provides the maximum power
                  algorithm, largely used in circuit design applica-       that the device can handle without multipactor
                  tions, ensures convergence, but at the cost of           breakdown.
                  a low efficiency. So, the design procedure has
                  been improved using a suitable combination               Distribution of electromagnetic field inside
                  of optimization algorithms in each parameter             the filters
                  extraction phase and also in the optimization            This section describes the procedure for obtai-
                  needed to obtain x*os. Robust non-gradient meth-         ning the distribution of electrical field inside the
                  ods (direct search and simplex) are used at the          structures as a function of the frequency.
                  beginning, and, after some iterations, when we
                  are close to the minimum, an efficient gradient          All-metal cavities filter
                  algorithms (Broyden-Fletcher-Goldfarb-Shanno             The field distribution is obtained from the mul-
                  (BFGS)) is used to refine the solution. This com-        timodal scattering matrices (GSMs) of each one
                  bination of algorithms has been proved to per-           of the segments that compose the structure of
                  form better than one algorithm alone. The shift          the filter. In Fig. 2 the different segments and
                  from one optimization algorithm to another               matrices are shown. GSMs of the step (S2, S4, S6,
                  one is controlled by the parameter termination           S8…) can be calculated following the well-known
                  tolerance xtol, the termination tolerance of the         Mode Matching Method [15], and the GSMs of
                  error function (ftol), and the maximum number of         the lines (S1, S3, S5, S7…) are obtained through
                  function evaluations (nFmax) permitted to each           analytic expressions. The global GSM is obtained
                  method. ftol is higher for the first algorithm, and      using a new efficient recursively connection
                  its value is decreased in each subsequent algo-          technique proposed in [16].
                  rithm. The shift from one algorithm to another,
                  as well as the rest of the whole design process is       Fig. 3 shows the regions where the electric field is
                  fully automated, so that no human intervention           calculated. For each region the field distribution
                  is needed at all.                                        is obtained by using the following equation [17]:

                        4. Multipactor breakdown
                            in waveguide filters
                  Multipactor effect prediction                            where
                  The Hatch and Williams [12] model has been               Mi is the number of modes in the i segment of
                  used for the study of the multipactor effect insi-       the filter. Typically Mi=11.
                  de the filters. In this model, the maximum input
                  power without multipactor breakdown is calcu-            xi and zi are the coordinates as defined in Fig. 3.
                  lated by using the electric field distribution insi-
                  de the structure.

                  In the model, the “Voltage Magnification Factor”
                  VMF [13] is defined as the maximum voltage in
                  the structure versus the input voltage (Vin) for
                  all the frequencies. This factor is calculated for all
                  the points inside the filter and the VMFmax is de-
                  fined as the maximum of VMFs. During this work
                  we have found that the maximum of electrical               Figure 2. Segments and GSMs matrices of all-
                  field appeared always in the same point inside            metal cavities filter.

108                                                                             ISSN 1889-8297 / Waves      · 2009 · year 1
am(i) y bm(i) are the modal vectors of incident and
reflected waves between segments i-1 and i as
defined in Fig. 2.

        is defined in equation.

bi is the height and ai the width of each section.

                                                         Figure 3. Regions for the computation of the electric field.

Filter loaded with dielectric cylinders
Fig. 4 shows the filter with dielectric cylinders
and the different segments in which the filter is
divided. There are three different types of seg-
ments: lines, steps and segment of line loaded
with dielectric cylinder. For each one of them a
different method is used for the computation of
GSMs and the electric field. As in the previous
filter, the GSMs of the steps (S2, S4, S8, S10…) are
calculated by using the Mode Matching Method
[15] and the GSMs of the lines (S1, S3, S5, S7…) are
computed analytically. For obtaining the GSMs
of the segments loaded with dielectric cylinders         Figure 4. Segments and GSMs matrices of the filter loaded with dielectric cylinders.
(S6,S12…) the hybrid mode matching method is
used [17]. Then all the matrices are connected
as described in [16] in order to get the global
GSM of the filter. For regions i=1, 3, 5, 6a, 7, 9,
11… (see Fig. 5) the electric field is calculated as
described in the previous subsection. The field in
regions 6b, 12b... (see Fig. 5) is obtained by using
the equation , where Jp and H(2) are the Bessel
and second order Hankel functions, and in and cn
are the incident and scattered spectrum coeffi-
cients in cylindrical coordinates.

                                                         Figure 5. Regions for the calculation of electric field of the filter loaded with die-
                                                        lectric cylinders.

Finally, in regions 6c, 12c… the field is obtained     narrow waveguide, while it is propagating in the
by the method described in [8], as follows:            input wider waveguide.

                                                       The procedure followed to calculate the field in-
                                                       side this filter is similar to the methodology des-
                                                       cribed in the two previous sections.

where coefficient sn is:                                                  5. Results
                                                       High-Order H-plane waveguide filter for spa-
                                                       ce applications at K-Band
                                                       The first example under consideration is a con-
                                                       ventional H-plane waveguide filter with coupled
                                                       cavities for space applications at the K-band. The
                                                       ideal transfer function is a standard nine-pole
                                                       Chebychev response of 96 MHz bandwidth cen-
                                               1.10    tered at 17.3 GHz.
and r the radius of the dielectric post.
                                                       The cavity lengths and coupling aperture widths
Evanescent mode filter loaded with dielectric          of the filter have been chosen as design parame-
cylinders                                              ters (see Fig. 8). The input and output wavegui-
In an evanescent mode filter, the fundamental          des of the filter, as well as the resonant cavities,
mode TE10, is below the cutoff frequency in the        are standard WR-62 waveguides (a=15.799 mm,

Waves · 2009 · year 1 / ISSN 1889-8297                                                                                                   109
                              Figure 6. Segments and GSMs matrices of evanes-
                             cent filter with dielectric cylinders

                                                                                         Figure 9. Responses of the H-plane waveguide
                                                                                      filter. Coarse model response at x* versus the fine
                                                                                     model response at xem.

                                                                                     Tunable H-plane waveguide filter for space
                                                                                     communication systems
                                                                                     In order to test the performance of the design
                                                                                     procedure with more complex structures, two
                                                                                     tunable H-plane coupled cavity filters have been
                              Figure 7. Regions for calculating the electric field   considered. These filters were originally designed
                             of the evanescent filter with dielectric cylinders.     and manufactured in [20], where the design was
                                                                                     performed manually. The same filters have been
                            b=7.899 mm). The length of all the coupling win-         re-designed with the CAD tool proposed in this
                            dows has been chosen to be 2 mm. For the design          work. The tuning elements are penetrating posts
                            of this filter, the same modal simulator has been        of square cross-section placed at the center of
                            used both as the coarse and the fine model. This         each cavity and each coupling window (see Fig.
                            modal simulator characterizes the planar discon-         10). As proposed in [20], the use of these tuning
                            tinuities using the Method of the Moments (MoM)          posts allows the use of a common base structure
                            according to the traditional Galerkin procedu-           for obtaining filters with responses centered at
                            re [18]. When used as a fine model, the number           different frequency bands. The only difference in
                            of accessible modes, number of basis functions           the filters at each frequency band is the penetra-
                            in the MoM, and number of kernel terms in the            tion of the tuning posts.
                            integral-equation are high enough to obtain very
                            accurate results. On the other hand, when used as        The ideal transfer function is a four-pole stan-
                            a coarse model, a small number of modes is con-          dard Chebychev band-pass response of 300
                            sidered in order to obtain a faster simulator at the     MHz bandwidth centered at 11 GHz and 13 GHz.
                            expense of a less accuracy. The initial values of        The input and output waveguides of the filter, as
                            the design parameters (x(0)) have been calculated
                                                       os                            well as the resonant cavities, are standard WR-75
                            according to the method described in [19]. Fig.          waveguides (a=19.050 mm, b=9.525 mm). The
                            9 shows the comparison between the response              length of all the coupling windows has been
                            of the fine model at the final solution in VS (xem)      chosen to be 2 mm. The sides of the posts are
                            and the response of the coarse model at x* . It can
                                                                        os           fixed to 4 mm in the cavities and 2 mm in the
                            be observed that the desired objective function          coupling windows.
                            has been satisfactorily recovered in the VS. This
                            solution has required 185 s of CPU time in a 2.4         The design with ASM using segmentation and
                            GHz Pentium IV PC platform.                              hybrid optimization required 3 ASM iterations
                                                                                     for both filters under severe convergence cri-

                                                                                       Figure 10. Manufactured tunable filters with tu-
 Figure 8. A four cavities H plane rectangular waveguide filter.                      ning elements. Common base and 11 GHz top.

110                                                                                       ISSN 1889-8297 / Waves     · 2009 · year 1
                                                                                                                 A different
                                                                                                                 method is
                                                                                                                 used for the
                                                                                                                 analysis of
                                                                                                                 each type
                                                                                                                 of building

  Figure 11. Measurements of the manufactured
 prototypes with tuning elements.

terion. The design for the filters centered at 11
and 13 GHz required a total CPU times of 49’50’’
and 33’42’’, respectively, in a PC with Pentium
IV processor at 1.7 GHz. Since the fine model is
about 250 times slower than the coarse model,
the total CPU time required for the direct design
of such filters without ASM would be of about              Figure 12. H-plane waveguide filter with dielectric
25 hours. This represents an improvement by a             resonators.
factor of 30, and clearly proves the advantage of
using ASM for the design of complex waveguide            be observed that the desired objective function
devices. The filters have been manufactured in           has been satisfactorily recovered in the VS. This
two different pieces, an H-plane base structure          solution has required about 2 hours of CPU time
and a separated top cover including all the tun-         in a 3 GHz Pentium IV platform. The total length
ing elements. To reduce costs, the same H-plane          of the filter (l1+l2+l3+l4+5t) is reduced by al-
base has been used for both filters. The common          most 50% when compared with the same filter
H-plane base and the two different tops includ-          without dielectric posts, with the correspondent
ing the tuning elements for the filters at 11 and        benefit in terms of volume and mass reduction,
13 GHz were manufactured (see Fig. 10) and               so critic in satellite communication systems.
measured (see Fig. 11).
                                                         Comparative study of multipactor breakdown
H-plane waveguide filter with dielectric reso-           The last part of this work evaluates the risk of
nators                                                   multipactor breakdown in a set of filters. In or-
The last structure under consideration is an H-          der to have a fair comparison the filters should
plane coupled cavities filter with circular dielec-      provide the same frequency response, so we
tric posts placed in the middle of each cavity (see      designed three different filters: all metal cavities,
Fig. 12(a)). The ideal transfer function is a standard   cavities loaded with dielectric cylinders and eva-
four-pole Chebychev response of 300 MHz band-            nescent mode loaded with dielectric cylinders
width centered at 11 GHz. The input and output           filters, which present the same frequency res-
waveguides of the filter, as well as the resonant        ponse shown in Fig. 13.
cavities, are standard WR-75 waveguides (a=19.05
mm, b=9.525 mm). The relative permittivity of the        It is important to notice that during the work
dielectric posts is chosen to be 24, and the length      we have considered that the multipactor break-
of all the coupling windows have been chosen to          down can only appear between two electric
be 2 mm. The remaining dimensions of the struc-          plates containing a normal field, so for the cal-
ture (cavity lengths, coupling aperture widths           culation of the power that a particular filter can
and radii of the dielectric posts) have been cho-        handle we have used the field inside that filter
sen as design parameters. The design procedure           but outside the dielectric cylinders. All the die-
described in section III can not be directly applied     lectric cylinders used in the filters have a dielec-
to the design of this kind of filters. It is necessary   tric permittivity Ɛr=24.
to use a genetic algorithm, since a good start-
ing point can not be easily obtained, as well as         All-metal cavities filter
to suppress the segmentation strategy, since the         During the study the authors found that the
coupling among cavities is much stronger that in         maximum of the electric field was always loca-
all-metallic filters. Again the same simulation tool     ted on the central longitudinal axis of the filter,
is used as the coarse and fine model. This simu-         and in the middle of the second cavity indepen-
lation tool is described in [21]. It uses a suitable     dently of the frequency value. Fig. 14 shows the
combination of an analytical method and a hybrid         maximum input and output power without mul-
technique which copes with the different parts of        tipactor breakdown as a function of the frequen-
the filter structure. Fig. 12(b) shows the compari-      cy. It is interesting that inside the pass band the
son between the response of the fine model at            amount of input and output power that the filter
xem and the ideal response of the filter. It can         can handle is the same, around 2500 W, and that

Waves · 2009 · year 1 / ISSN 1889-8297                                                                                      111
 A higher
 the power

                Figure 13. Scattering parameters S11 and S21 of
                the H-plane filters under study.                            Figure 15. Maximum output power without mul-
                                                                            tipactor breakdown for the cavities filter loaded
                                                                            with dielectric cylinders, loss tangents tgδ=0,
                                                                            tgδ=10-3, tgδ=10-4

                Figure 14. Maximum input and output power that
                the all-metal cavities filter can handle without multi-
                pactor breakdown as a function of frequency.
                                                                            Figure 16. Maximum output power without mul-
              outside this band the power is not limited by the             tipactor breakdown for the evanescent mode filter
              multipactor risk but by the electromagnetic res-              loaded with dielectric cylinders, loss tangents
              ponse of the filter.                                          tgδ=0, tgδ=10-3, tgδ=10-4

              Filter loaded with dielectric cylinders                     ller than the all-metal one, which makes that the
              In this filter the electric field was concentrated          electric field is more concentrated in the filter
              inside the dielectric cylinders, specifically there         and that the risk of multipactor breakdown in-
              was a maximum of field inside the second cylin-             creases. Nevertheless, when loading this filter
              der, being the maximum of field outside the die-            with dielectric cylinders, the output power wi-
              lectric cylinders considerably lower than in the            thout multipactor breakdown (see Fig. 16) can be
              case of the all-metal filter. Nevertheless, loading         higher than in the all-metal filter, since the field
              the filters with a dielectric material can introdu-         trends to concentrate inside the dielectric cylin-
              ce losses in the filter response that can affect the        ders. The figure also shows the output power for
              output power that the filter can handle. Fig. 15            different dielectric materials, with different loss
              shows the output power that the filter can han-             tangent factors, concluding that a good quality
              dle without the risk of multipactor breakdown               factor dielectric (tgδ=10-4) can provide a power
              for dielectric materials with different loss factors.       response similar to the ideal one, while a worse
              Even with a loss tangent of 10-3 this filter can            dielectric reduces this power handling but main-
              handle the double of power than the all-metal               tains it above the all-metal one.
              one. Moreover, with a rather high quality factor
              (tgδ=10-4) the behavior of the filter does not di-          Comparison of results
              vert from the ideal (lossless) case.                        It is interesting to show a comparative study of the
                                                                          three filters considering three relevant items: size,
              Evanescent mode filter loaded with dielectric               maximum field inside the filters and maximum
              cylinders                                                   output power without multipactor risk. Table II
              The evanescent mode filter is substantially sma-            lists the total length of the three filters. The eva-
                                                                          nescent filter presents a reduction in size of about
                                                                          50% comparing to the all-metal case, and the cavi-
                                                                          ties filter with dielectric cylinders is about 60% of
                Table 2. Lenghts of the three filters.                    the original size. The following table presents the
                                                                          maximum value of the electric field inside the fil-
                                                                          ters, for both cases: inside the dielectric cylinders
                                                                          and outside them. When having filters loaded with
                                                                          dielectric materials, the maximum of field is always
                                                                          located inside the dielectric cylinders. This pheno-
                                                                          menon enables the increase of power without risk
                Table 3. Maximum field (tgδ =1e-4)                        of multipactor as shown in Fig. 17. Fig. 17 presents

112                                                                            ISSN 1889-8297 / Waves      · 2009 · year 1
                                                                   IEEE Trans. Microwave Theory Tech., vol. 43, no.
                                                                   12, pp. 2874-2881, Dec. 1995.
                                                               [4] J. W. Bandler, S. Cheng, Q. S.and Dakroury, A. S.
                                                                   Mohamed, K. Bakr, M. H. Madsen, and J. Sön-
                                                                   dergaard, “Space mapping: The state of the
                                                                   art,” IEEE Trans. Microwave Theory Tech., vol.
                                                                   52, no. 1, pp. 337-361, Jan. 2004.
                                                               [5] M. Guglielmi, “Simple CAD procedure for mi-
                                                                   crowave filters and multiplexers,” IEEE Trans.
                                                                   Microwave Theory Tech., vol. 42, no. 7, pp.
                                                                   1347-1352, July 1994.
  Figure 17. Comparative chart of the output pow-              [6] J. T. Alos and M. Guglielmi, “Simple and effec-
 er for all the filters (dielectric loss factor: tgδ =1e-4).       tive EM-based optimization procedure for mi-
                                                                   crowave filters,” IEEE Trans. Microwave Theory
a comparative of the maximum output power wi-                      Tech., vol. 45, no. 5, pp. 856-858, May 1997.
thout multipactor risk for the three filters under             [7] J. V. Morro, P. Soto, H. Esteban, V. Boria, C. Bachi-
analysis considering that the filters loaded with                  ller, M. Taroncher, S. Cogollos, and B. Gimeno,
dielectric cylinders present low losses (tgδ=10-4). It             “Fast automated design of waveguide filters
can be observed that the cavity filter loaded with                 using aggressive space mapping with a new
dielectric cylinders can handle more than double                   segmentation strategy and a hybrid optimiza-
the power of an all-metal filter.                                  tion algorithm,” IEEE Trans. Microwave Thoery
                                                                   Tech., vol. 53, no. 4, pp. 1130-1142, April 2005.
                                                               [8] H. Esteban, S. Cogollos, V. E. Boria, A. A. San Blas,
                  Conclusions                                      M. Ferrando “A New Hybrid Mode-Matching/
                                                                   Numerical Method for the Analysis of Arbi-
A case study of advanced optimization techniques                   trarily Shaped Inductive Obstacles and Dis-
for the automated design of complex waveguide                      continuities in Rectangular Waveguides” IEEE    .
filters for space applications has been presented in               Trans. Microwave Theory Tech., vol. 50, no. 4,
this paper. A complete automated design tool has                   pp. 1219–1224, April, 2002.
been developed based on ASM enhanced with                      [9] Ansoft Corporation. [Online]
segmentation and hybridization schemes. This              HFSS: 3D Electro-
tool has been successfully applied to the practical                magnetic Simulation. 2008.
design of H-plane coupled cavities filters with and            [10] M. Guglielmi, “Simple CAD procedure for mi-
without tuning elements, and for the design of H-                  crowave filters and multiplexers,” IEEE Trans.
plane filters with dielectric posts. The multipactor               Microwave Theory Tech., vol. 42, no. 7, pp.
effect in the filters designed with our CAD tool has               1347-1352, July 1994.
been analyzed following a novel analysis techni-               [11] J. V. Morro, H. Esteban, P. Soto, V. E. Boria, C. Ba-
que that enables also the computation of the elec-                 chiller, S. Cogollos, and B. Gimeno,“Automated
tromagnetic field inside the structure.                            design of waveguide filters using aggressive
                                                                   space mapping with a segmentation strategy
                                                                   and hybrid optimization techniques,” in Proc.
             Acknowledgment                                        of the IEEE Int. Microwave Symp., Philadelphia,
                                                                   June 2003, pp. 1215-1218.
The authors would like to thank Dr. M. Gugliel-                [12] A.J.Hatch, H.B.Williams, “The secondary elec-
mi, European Space Research and Technology                         tron resonance mechanism of low-pressure
Center (ESTEC)-European Space Agency (ESA),                                                               .
                                                                   high-frequency gas breakdown” Journal of
Noordwijk, The Netherlands, for providing proto-                   Applied Physics, vol. 25, pp. 417-423. April 1954.
types and measurements of real filters conside-                [13] A. V. M. Ludovico, G. Vercellino and L. Acca-
red in this paper.                                                 tino, “Multipaction análisis in high power an-
                                                                   tenna diplexers for satellite applications” Pro-
                                                                   ceedings of the Workshop on Multipactor, RF
                   References                                      and DC Corona and Passive Intermodulation
                                                                   in Space RF Hardware, pp. 109. ESTEC, Noord-
[1] R. Udiljak, “Multipactor in Low Pressure Gas”.                 wijk, The Netherlands September, 2000.
    Master Thesis. Department of Electromagne-                 [14] ESA/ESTEC. Multipactor Calculator. [Online]
    tics, School of Electrical Engineering, Chal-         April 2007
    mers University of Technology, Göteborg,                   [15] J.M.Reiter, F.Arndt “Rigorous analysis of arbi-
    Sweden 2004.                                                   trarily shaped H- and E-plane discontinuities
[2] R. Udiljak, “Multipactor in Low Pressure Gas                   in rectangular waveguides by a full-wave
    and in Nonuniform RF Field Structures” PhD                     boundare contour mode-matching method”                .
    Thesis Department of Radio and Space Scien-                    IEEE Trans. on Microwave Theory and Tech,
    ce, Chalmers University of Technology, Göte-                   vol. 43, no. 4, pp. 796-801. April 1995.
    borg, Sweden 2007.                                         [16] C.Bachiller, H.Esteban, V.E.Boria, A.Belenguer,
[3] J. Bandler, R. Biernacki, S. Chen, R. Hemmers,                 J.V.Morro.“Efficient Technique for the Cascade
    and K. Madsen, ”Electromagnetic optimiza-                      Connection of Multiple Two Port Scattering
    tion exploiting aggressive space mapping,”                                 .
                                                                   Matrices” IEEE Transactions on Microwave

Waves · 2009 · year 1 / ISSN 1889-8297                                                                                       113
         Theory and Techniques, vol. 55, no. 9, pp 1880-         Valencia as an assistant lecturer. She is secretary of
         1886, September 2007                                    the iTEAM Institute of Multimedia Technology and
      [17] H. Esteban,“Análisis de Problemas Arbitrarios         Communications of the Polytechnic University of
         de Dispersión Electromagnética Mediante                 Valencia. She is teaching signal and systems theory
         Métodos Híbridos” PhD Thesis, Departamento
                                ,                                and microwaves. She has participated in several
         de Comunicaciones, Universidad Politécnica              teaching innovation projects as the development
         de Valencia, Spain 2002.                                of GUIs for teaching electromagnetic phenomena.
       [18] G. Gerini, M. Guglielmi, and G. Lastoria,            She is now working in her Ph.D. Thesis on electro-
         “Efficient integral equation formulations for           magnetism and radiofrequency circuits.
         admittance or impedance representation of
         planar waveguide junctions,” IEEE MTT-Symp.
         Dig., vol. III, pp. 1747-1750, 1998.                                            Héctor Esteban González
      [19] P. Soto, J. Gómez, A. Bergner, V. E. Boria, and R.                            received the degree in Te-
         Chismol, “Automated design of waveguide fil-                                    lecommunications Engi-
         ters using space mapping optimization,” in Proc.                                neering from the Polytech-
         of 3rd Eu. Conf. on Numerical Meth. in Electro-                                 nic University of Valencia
         magnetism, Poitiers, March 2000, pp. 228-229.                                   (UPV), Spain, in 1996, and
      [20] V. E. Boria, M. Guglielmi, and P. Arcioni, “Com-                              the Ph.D. degree in 2002.
         puter-aided design of inductively coupled                                       He collaborated with the
         rectangular waveguide filters including tu-                                     Joint Research Centre, Eu-
         ning elements,” Int. J. of RF and Microwaves            ropean Commission, Ispra, Italy. In 1997, he was
         Computer-Aided Engineering, vol. 8, no. 3, pp.          with the European Topic Centre on Soil (Euro-
         226-236, May 1998.                                      pean Environment Agency). He rejoined the UPV
      [21] C. Bachiller, H. Esteban, V. E. Boria, J. Morro, L.   in 1998. His research interests include methods
         Rogla, M. Taroncher, and A. Belenguer,“Efficient        for the full- wave analysis of open-space and gui-
         CAD tool fo direct-coupled-cavities filters with        ded multiple scattering problems, CAD design of
         dielectric resonators,” in 2005 IEEE AP-S Int.          microwave devices, electromagnetic characte-
         Symp. Dig., Washington D.C., June 2005.                 rization of dielectric and magnetic bodies, and
                                                                 the acceleration of electromagnetic analysis me-
                                                                 thods using the wavelets and the FMM.
                                                                                          Vicente E. Boria Esbert
                              José Vicente Morro                                          received the Ingeniero de
                              received the Telecom-                                       Telecomunicación and the
                              munications Engineering                                     Doctor Ingeniero de Te-
                              degree from the Universi-                                   lecomunicación degrees
                              dad Politécnica de Valen-                                   from the Universidad Po-
                              cia (UPV), Valencia, Spain,                                 litécnica de Valencia, Va-
                              in 2001, and is currently                                   lencia, Spain, in 1993 and
                              pursuing his Ph.D. degree                                   1997, respectively. In 1993
                              at UPV. In 2001, he beca-          he joined the Departamento de Comunicacio-
      me a Research Fellow with the Departamento                 nes, Universidad Politécnica de Valencia, where
      de Comunicaciones, UPV. In 2003 he joined the              he is Full Professor (since 2003). In 1995 and 1996
      Signal Theory and Communications Division,                 he was held a Spanish Trainee position with the
      Universidad Miguel Hernández, where he was a               European Space research and Technology Centre
      Lecturer. In 2005, he rejoined the Departamento            (ESTEC)-European Space Agency (ESA), Noordwi-
      de Comunicaciones, UPV, as an Lecturer. His cu-            jk, the Netherlands. Since 2003, he has served on
      rrent interests include CAD design of microwave            the Editorial Boards of the IEEE Transactions on
      devices and EM optimization methods.                       Microwave Theory and Techniques. He is also
                                                                 member of the Technical Committees of the
                                                                 IEEE-MTT International Microwave Symposium
                             Carmen Bachiller                    and of the European Microwave Conference. His
                             received her degree in              current research interests include numerical me-
                             Communication Enginee-              thods for the analysis of waveguide and scatte-
                             ring from the Polytechnic           ring structures, automated design of waveguide
                             University of Valencia in           components, radiating systems, measurement
                             1996. She worked from               techniques, and power effects in passive wave-
                             1997 to 2001 in the com-            guide systems.
                             pany ETRA I+D, S.A as a
                             Project Engineer in re-
      search and development on automatic traffic
      control, public transport management and public
      information systems using telecommunication
      technology. In 2001 she joined the Communica-
      tion Department of the Polytechnic University of

114                                                                   ISSN 1889-8297 / Waves      · 2009 · year 1

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