Fig.6.RT5880LZ substrate based fabricated prototype of the proposed 4×4 BM.
The simulated and measured S-parameters responses of the 4 × 4 Butler
matrix result for different ports are as shown in Fig. 7, respectively.
The P1 of the BM excited return loss was better than 17dB. This could be
seen in the simulation and measured results of the return loss and
insertion loss, which were S11 = -20.5 dB, S15 = -5.91 dB, S16 = -5.5
dB, S17 = -6.3 dB, S18 = -5.7 dB, and S11 = -18 dB, S15 = 6.41 dB, S16 =
-5.6 dB, S17 = -5.8 dB, S18 = -6.0 dB, illustrate in Fig. 7(a - b).
Hence, the average insertion loss for simulated and measured
(S15,S16,S17,S18) were -5.9, 6.0
±
2 dB,
respectively.
The P2 of the BM excited return loss was better than 14 dB. The
simulation and measured results of the return loss and insertion loss
were S22 = -25 dB, S25 = -6.35 dB, S26 = -6.4 dB, S27 = -5.43 dB, S28 =
-5.85 dB, and S22 = -34 dB, S25 = -6.72 dB, S26 = -6.65 dB, S27 = -5.81
dB, S28 = -6.76 dB, as illustrated in Fig 7(c - d), The average
insertion loss for simulated and measured (S25,S26,S27,S28) were -6.0,
6.5 ± 2, and dB, respectively. The P3 of the BM excited return loss was
better than 10 dB. The simulated and measured results of the return loss
and insertion loss were S33= -24 dB, S35 = -5.3 dB, S36 = -6.2 dB, S37 =
-6.25 dB, S38 = 6.4 dB, and S33= -15 dB, S35 = -5.8 dB, S36 = 6.7 dB,
S37 = 6.56 dB, S38 = -7 dB, as shown in Fig. 7 (e-f), The average
insertion loss for simulated and measured (S35,S36,S37,S38) were -6.0 ±2
dB, respectively. The P4 of the BM excited return loss was better than
15 dB. The simulated and measured results of the return loss and
insertion loss were S44= -20 dB, S45 = -5.4 dB, S46 = -5.18 dB, S47 =
-5.0 dB, S48 = -6.19 dB, and S44= -24 dB, S45 = -5.95 dB, S46 = -6.37
dB, S47 = -7.1 dB, S48 = -6.65 dB, as shown in Fig. 7(g-h). The average
insertion loss for simulated and measured (S45,S46,S47,S48)
were
-6.1 ± 2dB, respectively. All the results for P1, P2, P3, and P4 were at
centre frequency of 3.5 GHz.
The
overall results, when P1, P2, P3, and P4 were excited, the simulated and
measured proposed design 4 × 4 BM had good agreement between them,
although there some variation observed in the results due to the extra
loss phase shifts induced by the cable and connector.