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The intrinsic characteristics of LDMOS transistor amplifier can be extracted by removing the simulated characteristics of the input side and output side of test fixtures from the overall measured characteristics. In addition, impedance-matching networks are designed with these extracted S-parameters of the LDMOS transistor amplifier. The transistor used in this work is an MRF21030 LD-MOS 30W transistor provided by Freescale Semiconductor, Inc., and biased such that I DS_DQ is equal to 200 mA. Figures 4(a) and 4(b) show the measured and simulated S-parameters of the impedance matched transistor amplifier in the frequency range from 2.0 to 2.3 GHz. The maximum deviations of the measured ͉S 11 ͉, ͉S 21 ͉, and ͉S 22 ͉ from the simulated ͉S 11 ͉, ͉S 21 ͉, and ͉S 22 ͉ are 0.66, 0.17, and 0.13 dB, respectively. The simulated characteristics of impedance matching blocks can accurately predict the measured ones, as shown in Figures 4(a) and 4(b). CONCLUSIONIn this paper, we have presented a method of extracting 3D field simulation parameters of RF-band transistor amplifier test fixtures and demonstrated that a circuit model of the test fixtures can be constructed via pure 3D field simulation using the extracted material constants. The developed circuit model predicts measurement results within 0.5 dB.ABSTRACT: A simple square-slot antenna capable of providing a very wide impedance bandwidth of larger than 9 GHz is presented. The ultra-wideband operation for the proposed antenna is realized by using a novel feeding mechanism of loading an offset rectangular stub at the end of the microstrip feed line. With the proper offset distance of rectangular stub chosen, the proposed antenna can operate in the 2.78 -12.02-GHz frequency range and covers the UWB operating bandwidth of 3.1-10.6 GHz. The antenna radiation patterns at 3, 5.3, 7.9, and 10 GHz are also presented.ABSTRACT: An H-plane hybrid ring 3-dB power divider constructed with substrate integrated rectangular waveguide (SIRW) is proposed. Theoretical simulations are carried out at the X-and Ka-bands. The results show that the isolation between two output ports is high up to 35 dB and good 3-dB power division within the band of interest is observed also, that is, less than 0.3-dB derivation in the band of interest. In addition, the simulation results at the X-band shows a bandwidth of 10% at Ϫ15 dB. A prototype in the Ka-band is fabricated and the measured data at the Ka-band shows a bandwidth of 7% at Ϫ15 dB, in good agreement with simulation.

The intensity-temporal profiles of the converted S1 wave (at the fiber output end) and the control P1 wave (at the fiber input end) are demonstrated in Figure 3 (P1 is 10 Gb/s) and 4 (P1 is 20 Gb/s) to show the pulse properties and conversion feasibility in the dispersion region. It can be seen that the information (intensity and phase profiles) of P1 is imprinted on the S1 wave. Although the conversion efficiency will decrease as the bit rate increases, the decrease in our model can be compensated by the Raman amplifications from S2 and P2 waves. Clearly, the width of pulses will be broadened because of the dispersion effects, and also will broaden further at a higher repetition rate. The distortion of the profile and overlap of the pulse will occur if higher bit rates are used. CONCLUSIONA novel wavelength conversion scheme, based on the groupvelocity matched fiber Raman-resonant FWM, has been proposed where we can use a long fiber (L ϭ 500 m) in the converter and employ a high-power laser diode. With the appropriate arrangement of pump and Stokes waves in the polarization-preserving birefringent fibers, we have presented a novel simulation model and numerically demonstrated the power and temporal evolutions of the converted and pump signals. The results of pulse broadening and conversion efficiency have also been discussed. The scheme is compact and practical for use in flexible and reconfigurable wavelength-reuse networks. MULTI-FREQUENCY CHARACTERISTICS OF ANNULAR-RING SLOT ANTENNAS

Hybrid Modes Characteristics in Multilayered Faraday Chirowaveguides," .I. Electromagn. Woes Appl., to be published. Receiwd 5-30-95; revised 9-5-95 ABSTRACT A simple design of a dual-frequency microstrip antenna using a single rectangular patch and a single probe feed is described. Experimental results of the antenna resonating at frequencies of about 1.42 and 1.54 GHz are presented. Measurements are uerijed by the theoretical results obtained from full-wave solutions. 0 I996 John Wiley & Sons, Inc. 606-607. 309-311.

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