Antennas with Non-Foster Matching Networks phần 5

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Antennas with Non-Foster Matching Networks phần 5P1: RVMMOBK060-01 MOBK060-Aberle.cls January 19, 2007 17:23 38 ANTENNAS WITH NON-FOSTER MATCHING NETWORKS m3 freq = 104.0MHz dB(S(1,1)) = -20.022 0 -10 dB(S(1,1)) m3 -20 -30 -40 0 50 100 150 200 250 300 350 400 450 500 freq, MHz (a) 1.2 1.0 0.8 MuPrime1 0.6 0.4 0.2 0.0 0 50 100 150 200 250 300 350 400 450 500 freq, MHz (b) FIGURE 42: Simulated (a) return loss and (b) stability of the all-pass test circuit for the THS3202 FNR An all-pass implementation simulation in Agilent ADS with R3 = 50 is depicted in Fig. 44 where the FNR is placed inside a two-port data item box. To minimize noise and maximize gain, R1 and R2 are chosen to be as small as possible (200 and 400 , respectively) without affecting the performance of the FNR. The two 25 resistors on each side of the FNR complete the all-pass test circuit. The simulation results of Fig. 45 show that the −20 dB return loss bandwidth is only about 30 MHz, but the network is close to being unconditionally stable over almost the entire frequency range. We found that the input reactance Xin is negative and so might be compensated over a limited frequency range using a series inductor. By trial andP1: RVMMOBK060-01 MOBK060-Aberle.cls January 19, 2007 17:23 ANTENNAS WITH NON-FOSTER MATCHING NETWORKS 39 R R R3 R1 R=R2 Ohm R=R1 Ohm R ths3202_port R5 X2 R=R3 Ohm R Port Port R R6 P1 P2 R2 R R=R3 Ohm ths3202_port Num=1 Num=2 R=R1 Ohm R4 X1 R=R2 Ohm FIGURE 43: Schematic captured from Agilent ADS of the THS3202 FNR circuit formed by two back-to-back GNRs S-PARAMETERS 0 MuPrime S_Param MuPrime SP 1 Mu ...