Multiport-Amplifier-Based Architecture Versus Classical ... - IEEE Xplore

IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 54, NO. 12, DECEMBER 2006

4353

Multiport-Amplifier-Based Architecture Versus Classical Architecture for Space Telecommunication Payloads Alain Mallet, Aitziber Anakabe, Jacques Sombrin, Member, IEEE, and Raquel Rodriguez Abstract—This paper discusses the suitability of using a multiport amplifier (MPA) for a power section of space telecommunication payloads with power flexibility requirements. The performances of an MPA-based architecture are compared to those of a classical amplification architecture having one power amplifier 4 -band MPA comper beam. This study is based on a 4 posed of four paralleled traveling-wave tube amplifiers (TWTAs). First, a static model of the MPA has been extracted from conventional characterizations. Second, the MPA has been characterized in a realistic environment for telecommunication operation. The good agreement between measured and simulated data serves to validate the MPA model. Once the model has been validated, exhaustive simulations are performed to compare the performances of the MPA-based and classical architectures in terms of power consumption and the TWTA’s saturation power. As a result, the MPA approach proves to be an interesting solution because of its greater flexibility, lower power consumption, and lower saturation power required by the TWTAs. Index Terms—Communication systems, multiport circuits, power amplifiers (PAs), satellite communication, traveling-wave amplifiers, traveling-wave tubes (TWTs).

I. INTRODUCTION

I

N ORDER to efficiently meet the evolution of the market over the large lifetime of satellites and minimize businessplan risks, the increase of flexibility is demanded by operators for multimedia telecommunication payloads [1]. This flexibility can be expressed in terms of antenna coverage, power allocation on the coverage, or global satellite flexibility to manage in orbit a fleet of satellites. Phased-array antenna-based payload is the most flexible solution since it offers a high level of in-orbit reconfigurability [2]–[4]. In spite of its great flexibility, this approach is not generally implemented in current space telecommunication missions, which are not yet so demanding. Today, although technologically possible,1 2 phased-array antenna-based payload is not

Manuscript received April 7, 2006; revised July 10, 2006. The work of A. Anakabe was supported by the Spanish Commission of Science and Technology under Grant TIC2003-004453. A. Mallet, J. Sombrin, and R. Rodriguez are with the Centre National d’Etudes Spatiales, 31401 Toulouse, France (e-mail: [email protected]; [email protected]; [email protected]). A. Anakabe is with the Electricity and Electronics Department, University of the Basque Country, 48080 Bilbao, Spain (e-mail: [email protected]). Color versions of Figs. 1, 2, and 4–20 and Tables III and V are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TMTT.2006.885904 1Spaceway

mission at Boeing home page. [Online]. Available: http://www. boeing.com/defense-space/space/bss/factsheets/702/spaceway/spaceway.html 2Winds mission at Nasda home page. [Online.] Available: http://www. nasda.go.jp/projects/sat/winds/index_e.html

- and -band. often economically viable, especially in the Nevertheless, it will probably play a leading role in the evolution of future telecommunication space missions that involve a large number of beams with great flexibility requirements. Alternatively, using multiport amplifiers (MPAs) can be an attractive solution to respond to flexibility requirements in terms of power allocation switching since an MPA can intrinsically handle unbalanced traffic among beams and traffic variation over the time [5], [6]. In order to optimize the limited dc power available in the spacecraft, a very precise analysis is necessary. Furthermore, the saturation power required for the traveling-wave tube amplifiers (TWTAs) can be very close to the technological limits. Therefore, the adequate sizing of the payload must be accurately calculated in order to ensure the required transmission quality. That is to say, the saturation power of power amplifiers (PAs) and their associated operating point in terms of output backoff (OBO) must be carefully chosen in order to minimize either the dc power consumption or the saturation power for a given transmission quality. Other factors that have already been discussed in the literature must also be considered, e.g., the port-signal assignments [7], [8] and reliability [9], [10]. The aim of this paper is to demonstrate, through simulation and measurement results, the advantage of an MPA solution with respect to classical amplification architectures (with one PA per beam) provided that the operating point is carefully chosen in both cases. For that, the operation principle of MPAs and the main performances of the particular MPA characterized in this study are presented in Section II. The methodology proposed to select the optimum operating point, both from simulation and measurement results, is described step by step in Section III. This methodology is applied in Section IV to the analysis of a single TWTA under multicarrier excitation. Section V details the MPA model extraction and validation in the context of a representative multicarrier application. Finally, in Section VI, the performances of the MPA-based architecture and the classical architecture are compared for a TV direct video broadcasting application involving one single modulated carrier per channel. II.

-BAND MPA

A. MPA Operation Principle An MPA is composed of an array of PAs in parallel and a Butler matrix networks that consist pair of complementary of 90 hybrid networks [11]. A 4 4 MPA is shown in Fig. 1. The signal at each input in the MPA is divided into signals

0018-9480/$20.00 © 2006 IEEE

4354

IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 54, NO. 12, DECEMBER 2006

Fig. 3. Simplified transmission diagram.

2

Fig. 1. 4 4 MPA operation principle. Combination/cancellation principle for one input/output pair.

tube (TWT) from Thales Electron Devices, Velizy, France, an electronic power conditioner (EPC) from ETCA, Charleroi, Belgium, and a linearizer from Alcatel Alenia Space. Butler matrices have been developed by TILAB, Turin, Italy, and they are implemented in waveguide to minimize losses. The performances of the presented MPA are the following. W. • Output power per channel GHz. • Overall bandwidth • Instantaneous bandwidth MHz. • Frequency range: 19.7–20.2 GHz. dB at 4-dB OBO. • III. METHODOLOGY AND TOOLS Fig. 2.

Ka-band MPA.

with particular phase relationships. These signals are amplified separately in each PA and are recombined in the output Butler matrix. In this way, the signal at each input is amplified by all the PAs, but assembled at the corresponding output. The main advantage of this amplification architecture is that it provides intrinsic power flexibility since power is shared between the channels. The combined power of all the PAs is available for any channel, provided that the other channels do not require power at the same time. This power flexibility is obtained without necessarily increasing the power consumption. In contrast, an important drawback of the MPA is related to isolation losses between channels due to different electrical characteristics of each path. Besides, since all input signals are amplified at each PA, multicarrier operation is reached even when a single carrier is introduced at each input. In conclusion, the MPA is adapted to missions that require flexibility in terms of power reallocation and will be especially advantageous if input signals are already multicarrier. Therefore, the advantage of an MPA-based architecture can only be evaluated from realistic measurements or from simulations with accurate models and realistic signals. B. 4

4

-Band MPA

The studied MPA has been developed by Alcatel Alenia Space, Toulouse, France, under a European Space Agency contract. As is shown in Fig. 2, the MPA is composed of four -band paralleled TWTAs. Each TWTA is composed of a 120 continuous wave (CW) saturation power traveling wave

A. Optimization Criteria The overall performance of the transmission link is imposed by the required bit error rate (BER). For a given demodulator, this BER can be converted into a useful signal to parasitic signal . This ratio can be obtained from reratio quirements, the bit rate and the symbol rate as in the following: (1) The parasitic signal has different origins: intermodulation caused by nonlinear elements, interferences, and added noise. As schematically shown in the simplified transmission diagram of Fig. 3, the final goal is to ensure the BER while minimizing either the dc power consumption on the payload or the saturation power of the TWTAs. In order to compare the performances of different configura[12] and ratios. For tions, we make use of the a nonlinear PA family, these criteria allow the determination of the optimum operating point of the TWTAs in terms of OBO whatever the link budget, i.e., for any . These optimization criteria can be extracted from simulations or measurement results, as explained hereafter. The overall principle consists of ensuring the transmission quality for all users while minimizing the selected criterion ( or ). In principle, this fact imposes the rigorous study of each user case (each modulated carrier) one by one. However, in practice, the analysis will be focused on the most obviously deteriorated modulated carriers. and is detailed The procedure for determining in the following paragraphs.

MALLET et al.: MPA-BASED ARCHITECTURE VERSUS CLASSICAL ARCHITECTURE FOR SPACE TELECOMMUNICATION PAYLOADS

4355

In this paper, the dissipated power, which can also be a limiting parameter, is not taken into account. Nevertheless it could be easily analyzed in an analogous way by extracting as follows: (6) denotes the transmitted intermodulation signal (the where part reflected by the filters is dissipated in the payload). B. Simulation Methodology and Associated Software

Fig. 4. Illustration of the determination of optimum OBO from P =N and P =N curves.

Initially, the following parameters have to be obtained either from simulation or measurement results, as described in Sections III-B and C, respectively. • Input backoff (IBO): always referring to CW input saturation power (the sweep parameter). • OBO: referring to CW output saturation power. : total dc power consumption. • : useful signal power for the reference modulated carrier. • : signal-to-interference ratio for the reference modu• lated carrier. specification (given by (1) and associFrom the ratio as ated to the demodulator), we can deduce the (2)

All the simulations in this work have been carried out by means of Communication Library (COMLIB) software (a CNES internal simulation development), based on FORTRAN libraries. For that end, it has been specifically adapted to simulate the MPA’s behavior. COMLIB is based on a complex envelop simulation and it is used to simulate transmission chains taking into account linear and nonlinear distortions. Signal sample vectors are transformed alternately into time and frequency domains according to the description of the different elements. The MPA is modeled from the Butler matrices characterizachartion and the measured AM/AM, AM/PM curves and acteristics of TWTAs [13]. ratio is calculated from the equivalent gain method The [14]. The equivalent gain value, given in (7) as follows, is defined as the ratio between the portion of the output signal correlated with the input signal and the input signal itself: (7) with denoting the signal sample element (voltage value). Thus, the noise of the signal not correlated with the input is (8)

and can then be easily calculated, as in (3) and (4), respectively,

and the useful signal (9)

(3)

can then be computed as

(4) where (5) is the dc power corresponding to the reference modulated carrier with denoting the bandwidth of this reference modulated denoting the total bandwidth. carrier and and Once these parameters are obtained, curves can be plotted versus OBO. An illustrative example is given in Fig. 4. It can be seen that the minima of those curves correspond, respectively, to the optimal operating point in terms of dc consumption or in terms of saturation power. It is important to note that the minimum values of those two different criteria cannot be directly compared. Eventually, the saturation power and the operating point are chosen according to the absolute dimensioning parameter of the specific mission (dc power or TWTA’s saturation power).

(10) Finally, the parameters related with the two optimization criteria ( and ) can be calculated from these values following the procedure detailed in Section III-A. C. Measurement Methodology and Tools The measurements have been carried out in a transmission system bench (BST) developed at CNES under an internal advanced telecommunication program (ATF) program for test -band multimedia satellite systems. This and analysis of easily reconfigurable facility has been used to test the MPA in representative payload architectures with realistic signals. A photograph of the MPA characterization under the transmission system bench is shown in Fig. 5. Unlike simulation procedures, directly extracting the intermodulation signal from the overall interferences (intermodulation and noise) is not straightforward in the case of modulated

4356

IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 54, NO. 12, DECEMBER 2006

Fig. 5. MPA characterization under BST test-bench.

Fig. 7. P =N versus OBO for a single TWTA loaded with one, two, three, and six modulated carriers.

Fig. 6. (a) Demodulator “calibration” procedure. (b) Configuration example: TWTA with three modulated carriers.

multicarrier measurements. Therefore, we propose an indirect method consisting of the following two steps. Step 1) Determine the signal to interference ratio corresponding to the BER specification for a single modulated carrier [see Fig. 6(a)]. Step 2) Determine the amount of added noise needed to obtain the same BER for any configuration [see Fig. 6(b)]. and For a given BER, the signal to interference ratio can be extracted because the the signal to noise ratio demodulator is receiving the same useful signal to noise intermodulation ratio in both Steps 1) and 2).

Fig. 8. P =N versus OBO for a single TWTA loaded with one, two, three, and six modulated carriers.

TABLE I OPTIMUM OPERATING POINTS IN TERMS OF P AND ASSOCIATED P =N AND P =N FOR A TWTA LOADED WITH ONE, TWO, THREE, AND SIX MODULATED CARRIERS

IV. SINGLE TWTA OPERATION The determination of the optimum operating point in terms of OBO and the choice of the saturation power of PAs are illustrated here by their application to a single TWTA loaded with a different number of modulated carriers with an equal bit rate. curves for a TWTA loaded with one, two, three, The and six modulated carriers have been obtained from measurement results, as described in Sections III-A and C and are plotted in Fig. 7. It can be seen that the optimum OBO moves from 0.6 to 2.4 dB when changing from a single modulated carrier to multicarrier operation. curves for a TWTA with one, two, Similarly, the three, and six modulated carriers have been obtained from measurement results and are depicted in Fig. 8. In this case, the optimum OBO moves from 0.5 to 1.8 dB when changing from a single modulated carrier to multicarrier operation. As expected, when increasing the number of modulated carriers, the optimum operating point of the TWTA is obtained for a greater OBO since intermodulation caused by nonlinear elements increases with the number of modulated carriers. More-

over, we can state that the case of three modulated carriers can be considered almost as a multicarrier operation. Numerical results for the optimum operating point in terms of and are summarized in Tables I and II, respectively. It per carrier significantly increases (1.5 dB) can be seen that from 1–6 modulated carriers, in addition to a drastic increase in the required TWTA saturation power. Note that the optimum operating point depends on the chosen optimization criterion or . V. MPA CHARACTERIZATION FOR MODEL EXTRACTION AND VALIDATION A. MPA Modeling The following two types of characterizations have been performed in order to extract the MPA model.

MALLET et al.: MPA-BASED ARCHITECTURE VERSUS CLASSICAL ARCHITECTURE FOR SPACE TELECOMMUNICATION PAYLOADS

4357

TABLE II OPTIMUM OPERATING POINTS IN TERMS OF P AND ASSOCIATED P =N AND P =N FOR A TWTA LOADED WITH ONE, TWO, THREE, AND SIX MODULATED CARRIERS

Fig. 10. (a) Four beams of a typical Ka-band telecommunication multimedia system coverage. (b) Reference scenario.

Fig. 9. Comparison between measured and simulated P for the MPA.

=P characteristic Fig. 11. MPA-based architecture that fulfills the requirements.

• Nonlinear characterizations: AM/AM, AM/PM, and dc power consumption, as a function of input power, of each amplifying branch (mainly composed of a linearizer, TWTA, and phase and magnitude adjustment components). • Linear characterizations: -parameters of Butler matrices. In order to validate this nonlinear static model, measured and curves are superposed in Fig. 9. It can be simulated seen that a very good agreement has been obtained. B. MPA Model Validation on Realistic Instance In order to thoroughly validate the model for our specific use, a representative case of multicarrier operation for space telecommunication applications has been studied. The MPA has been characterized using the BST test-bench shown in Section III-C and the measurement results have been compared with simulations. This example has been presented in detail in [15]. Only a brief summary is given here, where illustrative comparisons between simulations and measurement results are provided. -band telecommunication Four beams of a typical multimedia system coverage with two frequencies and two polarizations are considered in this instance [see Fig. 10(a)]. 12 quadrature phase-shift keying (QPSK) modulated carriers are allocated in these four beams. During the mission, channel reallocation possibility is required. The 12 modulated carriers can be switched between the four beams. A frequency plan that satisfies the required mission and defines the chosen reference scenario is depicted in Fig. 10(b). The defined mission can be directly carried out using a 4 4 MPA, as shown in Fig. 11. The operating point of the MPA has been optimized using the methodology described in Section III.

Fig. 12. P =N and P

=N versus OBO for the MPA-based architecture.

Fig. 12 shows the and ratios as a function of the OBO (referring to the MPA CW saturation power) obtained from both simulation and measurement results. The optimum operating point varies from 1.1 to 1.6 dB depending on the criterion that we consider. Note that there is a very good agreement between measurements and simulated data. In addition to validating the accuracy of the MPA model, this application was used in [15] to compare MPA performances with classical amplification architecture performances, evidencing the advantage of the MPA for a multicarrier application with flexibility requirements. This cumbersome measurement campaign and the corresponding simulations confirmed the accuracy of the extracted MPA model. This model will be used in Section VI to evaluate, exclusively from simulation results, the advantage of an MPA for a power flexible application with a single modulated carrier, of variable symbol rate, per channel.

4358

IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 54, NO. 12, DECEMBER 2006

Fig. 13. Flexible bandwidth allocation illustration.

TABLE III DESCRIPTION OF THE THREE CONFIGURATIONS

VI. COMPARISON BETWEEN CLASSICAL AND MPA-BASED AMPLIFICATION ARCHITECTURES

Fig. 14. P =N curves for the determination of optimum OBO for the MPAbased architecture.

Fig. 15. P =N curves for the determination of optimum OBO for the MPAbased architecture. Level of carrier 1 from unbalanced configuration increased 0.5 dB.

A. Reference Scenario This second example concerns an application where a bandis allocated for the TV direct video broadcasting on width four beams with four antennas. Two polarizations are used: horizontal ( ) and vertical ( ). The bandwidth is considered to be shared between two beams in any desired configuration. As depicted in Fig. 13, is shared by beams 1 and 2 on polarization and reutilized in polarization for beams 3 and 4. Three representative configurations of this mission will be considered, which are: 1) balanced; 2) unbalanced; and 3) limit (see Table III). The “limit configuration” corresponds to the extreme case where only two beams among the four are used. In order to perform realistic simulations, actual values from the demodulator of the measurement BST test-bench are conis fixed to 3.25 dB, as it sidered in all cases. Thus, corresponds to this demodulator with the given BER specification (10 without coding). B. MPA-Based Architecture The defined mission can be directly carried out using a 4 4 MPA. The operating point of the MPA has been optimized using the methodology described in Section III in order to minimize (fixed to dc power consumption for the given curves are initially plotted 3.25 dB). For that, in Fig. 14, versus OBO for the three different configurations. The two curves traced in solid line correspond, respectively, to the two

modulated carriers of different rate involved in the “unbalanced configuration.” The lower rate modulated carrier (triangles) is the most degraded and represents the dimensioning case value, around because it corresponds to the higher 8.4 dB for 1.9-dB OBO. A solution to reduce the dc consumption consists of increasing the relative power level of this carrier. A parametric study has been performed on this relative level and an optimum over level of 0.5 dB has been obtained. The modified curves for the unbalanced scenario are updated in Fig. 15. This example illustrates the capability for compensating, at least partially, the pumping effect of the smallest carriers in the nonlinearities by increasing their relative level at the input. An optimum OBO of 1.8 dB is determined from Fig. 15 for optimizing . Fig. 16 shows the versus OBO curves for the four configurations. The optimum operating point is approximately 1.5 dB for this parameter. It is important to note that these optimum operating points are independent of the noise power density. The dimensioning configuration is now the limit configuraand . We will tion since it corresponds to higher now consider the noise power , extracted from the link budget, in order to determine the evolution, versus the OBO, of the required saturation power of the TWTAs and the associated dc power consumption of the MPA.

MALLET et al.: MPA-BASED ARCHITECTURE VERSUS CLASSICAL ARCHITECTURE FOR SPACE TELECOMMUNICATION PAYLOADS

Fig. 16. P =N curves for the determination of optimum OBO for the MPAbased architecture. Level of carrier 1 from unbalanced configuration increased 0.5 dB.

Fig. 17. P and P curves for the determination of optimum OBO for the MPA-based architecture corresponding to the limit case.

and

can be calculated as (11) (12)

where denotes the sum of the symbol rates of the different signals and “4” corresponds to the number of paralleled TWTAs in the MPA under study. In the configuration under study, Ms/s Besides, a noise density dBm/Hz W/Hz has been extracted from the considered link budget. The saturation power and dc power consumption computed from (11) and (12) are plotted in Fig. 17. The horizontal straight line corresponds to the maximum allowed saturation power of TWTAs (120 W). Thus, 1.8-dB OBO has been finally chosen as optimum operating point since the dc consumption is minimized and the saturation power of TWTAs is within the fixed limit. This leads to the following values: • optimum operating point: 1.8-dB OBO; • saturation power of TWTAs: 120 W; • dc power consumption: 830 W.

4359

Fig. 18. P =N and P =N curves for the determination of optimum OBO for the architecture without MPA.

C. Architecture Without MPA The architecture that fulfills the defined mission is very simple. It is composed of four independent TWTAs. Nevertheless, since each of the TWTA must be capable of amplifying a modulated carrier up to 35 Ms/s, all of them must have the same saturation power, fixed by this maximum symbol rate. According to the previously presented methodology, and curves are plotted in Fig. 18 versus OBO for the . given curve is flatter than It can be seen in Fig. 18 that the the one. Besides, the saturation power of TWTAs is the dimensioning parameter, because we have stated that it must remain below 120 W. Consequently, the optimum operating point dB in order to minimize . For the is chosen 0.55-dB optimum OBO, dB is obtained. In the configuration under study, with four TWTAs that must is be able to amplify a modulated carrier up to 35 Ms/s, given by (13) Ms/s and dBm/Hz W/Hz with (extracted from the link budget). W. Note that this saturation power This leads to required for the TWTAs is far beyond the limit that we have imposed (120 W). In order to calculate the dc power consumption, the optimal ratio is first operating point that ensures the required deduced in Fig. 19 for the three lower rate modulated carriers. This optimum operating point corresponds to the intersection versus OBO curve and the reference between each level (in this example, fixed to 3.25 dB). The corresponding degradation of the power-added efficiency (PAE) with increasing OBO appears in Fig. 20. Under fullcharge operation (35-Ms/s modulated carrier), the TWTAs operate at the modulated signal saturation power with maximum PAE. As the rate decreases (29, 16, and 3 Ms/s), the OBO increases and TWTAs operate with lower PAE. Table IV summarizes the operating points and the associated dc power deduced for the four modulated carriers. In the last column, the dc power consumption is normalized to the symbol rate in order to illustrate the overconsumption of the smaller modulated carriers.

4360

IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 54, NO. 12, DECEMBER 2006

TABLE V DC CONSUMPTION CALCULATION FOR THE THREE CONFIGURATIONS

Fig. 19.

C (N + I ) curves for the different symbol rates.

TABLE VI MAIN CHARACTERISTICS AND PERFORMANCES FOR THE TWO DIFFERENT ARCHITECTURES

Fig. 20. PAE versus OBO.

TABLE IV OPERATING POINT AND ASSOCIATED DC POWER FOR THE DIFFERENT SYMBOL RATES

The associated dc power for the three configurations can be calculated. The results are summarized in Table V.

creased due to the smaller PAE of the four TWTAs that operate with 4.2-dB OBO. In conclusion, MPA-based architecture leads, on average, to a lower dc power consumption because the limit case will rarely occur. Above all, using an MPA, the mission can be satisfied with TWTAs with appreciably lower saturation power. Flexible TWTAs could be an interesting solution to reduce dc power consumption because of the lower degradation of the PAE when operating with backoff. However, it should be noted that the TWTA’s saturation power requirement for this architecture could not be lowered using flexible TWTAs. The MPA has demonstrated its advantage even if it does not seem, at first sight, well suited to this configuration with one modulated carrier per beam. VII. CONCLUSION

D. Performances Comparison Table VI summarizes the dc power needed for the three configurations and the two different architectures with and without an MPA. In a classical amplification architecture, without an MPA, criterion has been used to determine the saturation the power of the TWTAs. The corresponding dimensioning input signal is one 35-Ms/s QPSK modulated carrier. For the limit case, a classical amplification architecture is less consuming than the MPA one (635 W against 831 W), as shown in Table VI. Nevertheless, since power flexibility requirement has been immust be evaluated for the dimensioning case, i.e., for posed, the balanced configuration. The solution with the MPA is, in this case, favorable in terms of dc power consumption (890–830 W). Indeed, dc consumption of the classical solution is highly in-

Flexibility is certainly a key factor in the next generation of telecommunication multimedia payloads. MPA is an attractive solution to partially answer the increasing flexibility requirements demanded by operators. However, the evaluation of the benefits associated to an MPA-based architecture must rely on representative measurements or on simulations performed with accurate models and realistic signals. In order to avoid laborious and time-consuming measurement campaigns required for each particular application, a model of the MPA has been extracted from a complete characterization process. This model has been validated through both CW signals and signals from a representative multicarrier application. A comparison of performances between the MPA-based and classical power amplification architectures has then been carried out for a power flexible application that involves a single modulated carrier per channel. MPA

MALLET et al.: MPA-BASED ARCHITECTURE VERSUS CLASSICAL ARCHITECTURE FOR SPACE TELECOMMUNICATION PAYLOADS

solution has been proven to be very attractive, as it leads to lower dc power consumption with lower saturation power TWTAs.

4361

[15] A. Mallet, A. Anakabe, J. Sombrin, R. Rodriguez, and F. Coromina, “Multi-port amplifier operation for -band space telecommunication applications,” in IEEE MTT-S Int. Microw. Symp. Dig., San Francisco, CA, Jun. 2006, pp. 1518–1521.

Ka

ACKNOWLEDGMENT The authors acknowledge the helpful collaboration of F. Coromina, European Space Agency (ESA), Noordwijk, The Netherlands, who participated in the definition and analysis of the tests. The authors wish to further acknowledge the assistance of F. Gizard, C. Laporte, T. Robert and J.P. Taisant, all of the BST/ATF Team, Centre National d’Etudes Spatiales (CNES), Toulouse, France. The authors further wish to thank L. Lapierre, CNES, P. Baretto-Da-Rocha and P. Frichot, both with Alcatel Alenia Space, Toulouse, France, and H. Fenech, Eutelsat, Paris, France, for helpful discussions. REFERENCES [1] V. Marziale, A. Pisano, and G. Di Paole, “Flexible payload technologies to enable multi mission satellite communication systems,” presented at the 24th AIAA Int. Commun. Satellite Syst. Conf. and Exhibit. San Diego, CA, Jun. 2006. -band satellite active [2] N. Seong, C. Pyo, J. Chae, and C. Kim, “ phased array multi-beam antenna,” in IEEE 59th Veh. Technol. Conf., May 2004, vol. 5, pp. 2807–2810. [3] A. Jacomb-Hood and E. Leir, “Multibeam active phased arrays for communications satellites,” IEEE Micro, vol. 1, no. 4, pp. 40–47, Dec. 2000. [4] S. Egami and M. Kawai, “A power-sharing multiple-beam mobile satellite in band,” IEEE J. Sel. Areas Commun., vol. 17, no. 2, pp. 145–152, Feb. 1999. [5] S. Egami and M. Kawai, “An adaptative multiple beam system concept,” IEEE J. Sel. Areas Commun., vol. SAC-5, no. 4, pp. 630–636, May 1987. [6] F. Andre, “Multiport power amplifier: A flexible architecture for multichannel amplification on board satellites,” in 5th IEEE Int. Vac. Electron. Conf., 2004, p. 268. [7] W. A. Sandrin, “The Butler matrix transponder,” COMSAT Tech. Rev., vol. 4, no. 2, pp. 319–345, Fall 1974. [8] M. Tanaka and Y. Suzuki, “Nonlinear distortion analysis of multiport amplifier,” presented at the 22nd AIAA Int. Commun. Satellite Syst. Conf. and Exhibit., Monterey, CA, 2004. [9] M. Tanaka and S. Egami, “Reconfigurable multiport amplifiers for in-orbit use,” IEEE Trans. Aerosp. Electron. Syst., vol. 42, no. 1, pp. 228–236, Jan. 2006. [10] F. Coromina and A. Martin Polegre, “Failure robust transmit RF front end for focal array fed reflector antennas,” presented at the 22nd AIAA Int. Commun. Satellite Syst. Conf. and Exhibit., Monterey, CA, 2004. [11] B. Piovano, L. Accatino, A. Angelucci, T. Jones, P. Capece, and M. Butler matrices Votta, “Design and breadboarding of wideband for multiport amplifiers,” in SBMO Int. Microw. Conf., Aug. 1993, vol. 1, pp. 175–180. [12] J. Sombrin, “A new criterion for the comparison of TWT and linearized TWT and for the optimization of linearizers used in transmission systems,” presented at the ESA/NATO Microw. Tubes for Space, Military, and Commercial Applicat. Workshop, Noordwijk, The Netherlands, Apr. 7–10, 1997. [13] C. Laporte, L. Lapierre, A. Mallet, and A. Anakabe, “Behaviour of a TWTA with a single or multicarrier input signal for telecommunication applications,” in 35th Eur. Microw. Conf., Paris, France, Oct. 4–6, 2005, pp. 1651–1653. [14] J. Lajoinie, E. Ngoya, D. Barataud, J. M. Nebus, J. Sombrin, and B. Riviere, “Efficient simulation of NPR for the optimum design of satellite transponders SSPAs,” in IEEE MTT-S Int. Microw. Symp. Dig., Baltimore, MD, Jun. 1998, vol. 2, pp. 741–744.

Ka

Ka

N 2N

Alain Mallet was born in Limoges, France, on November 24, 1971. He received the Ph.D. degree in microwave communications from the Microwave and Optical Communications Research Institute (IRCOM), Brive, France, in 1996. In 1993, he joined IRCOM, where he was involved with high-efficiency amplifier design methods. In 1999, he joined the Microwave and Time Frequency Department, Centre National d’Etudes Spatiales (CNES), Toulouse, France, where he is currently a Research Engineer involved in topics related to active components (characterization, modelization, simulation, and design).

Aitziber Anakabe was born in Barakaldo, Spain, in 1976. She received the Electronic Physics and Electronic Engineering degrees and Ph.D. degree in electronics from the University of the Basque Country, Bilbao, Spain, in 1999, 2000, and 2004, respectively. In 1999, she joined the Electricity and Electronics Department, University of the Basque Country, where she was involved with the stability analysis of nonlinear microwave circuits. In 2004, she joined Centre National d’Etudes Spatiales (CNES), Toulouse, France, as a Post-Doctoral Researcher. In 2005, she rejoined the Electricity and Electronics Department, University of the Basque Country. Her research deals with nonlinear analysis and modeling of microwave circuits and measurement techniques.

Jacques Sombrin (M’88), was born in Lons, France, in 1949. He received the Engineer degree from the École Polytechnique, Paris, France, in 1969, and the Engineer degree from the École Nationale Supérieure des Télécommunications (ENST), Paris, France, in 1974. In 1974, he joined the Centre National d’Etudes Spatiales (CNES), Toulouse, France, as a Microwave Engineer. He was involved with the modelization and simulation of the nonlinearities of TWTAs used in communication satellite payloads and on the design of elliptic filters. He is currently a Senior Expert and Assistant Director for Radio Frequency with CNES, where he is in charge of research and technology within this domain. His research interests include the increase of TWT efficiency and linearity, system simulation of nonlinearities and power consumption, and the global optimization of satellite payloads and communication systems. Dr. Sombrin is a Senior Member of the French Society of Electrical and Electronics Engineers (SEE).

Raquel Rodriguez was born in Barcelone, Spain, in 1979. She received the Telecommunications Engineering degree from the Universitat Politènica de Catalunya, Barcelona, Spain, in 2004. In 2004, she joined the Centre National d’Etudes Spatiales (CNES), Toulouse, France, as a Microwave Engineer. Her research interests are related to microwave circuits and technologies.