Arbitrary coupling arbitrary phase couplers with improved bandwidth

Abstract

In this study, an arbitrary coupling and arbitrary phase coupler with improve bandwidth is proposed. The proposed couplers use a series stub of electrical length θ at all ports which acts as matching element and thereby improves the effective bandwidth of the coupler. A lossless transmission line model is used to obtain design equations and design graphs. Return loss, isolation, amplitude and phase imbalances all four conditions are considered for bandwidth calculation. Two 3 dB couplers with phase difference of 30° and 45° and the third coupler with 4.77 dB coupling and phase difference of 60° are fabricated and measured to validate the proposed topology. Bandwidth improvement is obtained in all the cases. In some cases, the effective bandwidth is more than 100%.

Multi‐section broadband couplers with arbitrary phase differences and power‐dividing ratios

“…6 Thereafter, the co-designed couplers were developed towards arbitrary power-dividing ratio outputs, [7][8][9] compact size, 10,11 dual-band 12 and broadband operation. [13][14][15][16][17][18] The couplers with arbitrary phase differences include patch couplers, 8 coupled-line couplers, 13,14 and branch-line couplers. [15][16][17][18] By using tight-coupling coupled lines, the bandwidth of coupled-line couplers 13,14 can be extended at the cost of interspersed input/output ports.…”

“…[13][14][15][16][17][18] The couplers with arbitrary phase differences include patch couplers, 8 coupled-line couplers, 13,14 and branch-line couplers. [15][16][17][18] By using tight-coupling coupled lines, the bandwidth of coupled-line couplers 13,14 can be extended at the cost of interspersed input/output ports. Comparing with coupled-line couplers, the output ports of branch-line couplers are located at the same side, which will benefit the practical circuit layout.…”