5. DISCUSSION The experimental results for the structure show that high reflection (-33 dB) from the FSS occurs at the frequency of 10.60 GHz for a vertically polarized wave (Fig. 3), thus providing a 20-dB re- flection bandwidth of 900 MHz. An exactly identical observation is obtained for the horizontally polarized input wave. The simulation results for the structure show that high reflec- tion (-39 dB) from the FSS occurs at the frequency of 10.30 GHZ for a vertically polarized wave (Fig. 2), thus yielding a 20-dB reflection bandwidth of 780 MHz. A similar result is noted for the horizontally polarized input wave. The simulated result agrees with the experimental observation to a great extent. The only difference occurs in the resonance frequency, where a small deviation of 300 MHz is observed. The algorithm developed for this case requires very small computa- tional volume and time, yet the result very nearly conforms to the measured one. About 1 hour is sufficient to find the final result on a P-III 667-MHz PC. 6. CONCLUSION The simulation result for the structure has shown that more or less the same comparable property of the FSS is achieved with the measurement. At all frequencies in the spectrum, the nature of the response remains the same for both horizontally polarized and vertically polarized input waves. This result indicates that the proposed FSS behaves similarly when the polarization form the source is changed from vertical to horizontal or vice-versa. In our designed structure, the frequency response of the FSS was found to remain independent of the source polarization. In the periodically arranged structure, nonidentical dipole elements may be placed over the same substrate in order to increase the bandwidth without having any effect on the polarization independency. Or the same property may be achieved very conveniently by using a multilayer FSS and identical elements on each layer, but with different lengths. The lengths can be chosen very easily according to our requirements. This FSS may find applications in satellite commu- nication, especially in the field of radio astronomy where polar- ization from the source is completely unpredictable or need not be known. REFERENCES 1. N.D. Agrawal and W.A. Imbraile, Design of a dicroic cassegrain subreflector, IEEE Trans Antennas Propagat AP-27 (1979), 466 – 473. 2. G.H. Schennum, Frequency-selective surfaces for multiple frequency antennas, Microwave J 16 (1973), 55–57. 3. T.K. Wu, Double square loop FSS for multiplexing four (S/X/Ku/Ka) bands, IEEE Int AP-S Symp, Ontario, Canada, 1991. 4. K. Ueno et al., Characteristics of FSS for a multiband communication satellite, IEEE Int AP-S Symp, Ontario, Canada, 1991. 5. C.C. Chen, Transmission of microwave through perforated flat plates of finite thickness, IEEE Trans Microwave Theory Tech MTT-21 (1973), 1– 6. 6. S.W. Schneider and B.A. Munk, The scattering properties of super dense arrays of dipoles, IEEE Trans Antennas Propagat AP-42 (1994), 463– 472. 7. E.A. Parker, S. Hamdy, and R. Langley, Arrays of concentric rings as frequency-selective surfaces, Electron Lett 17 (1981), 880. 8. E.L. Pelton and B.A. Munk, Scattering from periodic arrays of crossed dipoles, IEEE Trans Antennas Propagat AP-27 (1979), 323–330. 9. C.H. Tsao and R. Mittra, Spectral-domain analysis of frequency se- lective surfaces comprised of periodic arrays of cross dipoles and Jerusalem crosses, IEEE Trans Antennas Propagat AP-32 (1984), 478 – 486. 10. K.S. Yee, Numerical solution of initial boundary value problems involving Maxwell’s equations in isotropic media, IEEE Trans Anten- nas Propagat AP-14 (1966), 302–307. 11. J.P. Berenger, A perfectly match layer for the absorption of electro- magnetic waves, J Comput Phys 114 (1994), 185–200. © 2005 Wiley Periodicals, Inc. A GaAs MONOLITHIC LINEAR-IN-DB WIDE-DYNAMIC-RANGE VARIABLE- GAIN AMPLIFIER WITH MATCHING COMPENSATION FOR 1.95-GHZ APPLICATIONS M. Detratti, 1 J. P. Pascual, 1 M. L. de la Fuente, 1 J. Cabo, 2 and J. L. Garcı ´a 1 1 Communication Engineering Department ETSIIT University of Cantabria Avda. Los Castros s/n 39005 Santander, Spain 2 Alcatel Espacio Tres Cantos Madrid, Spain Received 7 July 2004 ABSTRACT: This paper describes a method to design a compact lin- ear-in-dB variable-gain amplifier (VGA) with good input/output match- ing in a wide gain-control range. The method is theoretically supported and has been validated with the design of a 1.95-GHz GaAs fully mono- lithic VGA. Measured maximum gain is 18.8 dB with associated noise figure of 6.3 dB and 40-dB dynamic range with lower than 1.5-dB deviation from linearity, under a low control voltage from -0.4 V to -1.5 V. Good linearity with an output 1-dB compression of 12 dBm at maximum gain and associated 3 rd -order intercept point better than 22 dBm are also shown. The adjacent channel power ratio (ACPR) was measured at the 1.95-GHz WCDMA band, showing values better than -48 dBc at 885-KHz offset and -70 dBc at 1.98-Mhz offset over the whole control range. The chip size is 2  1.0 mm 2 and consumes only 34 mA from a supply voltage of 3.5 V. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 251–257, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop. 20602 Key words: variable gain amplifier (VGA); MMIC; linear-in-dB; matching; WCDMA 1. INTRODUCTION The use of FETs arranged in PI, tee, and bridged-T is quite common in the design of voltage-controlled variable attenuators [1]. The combination of such kinds of circuits with conventional amplifiers may result in a VGA with good performance. The main Figure 3 Measured normalized transmission coefficient  vs. frequency MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 44, No. 3, February 5 2005 251