Multiway wideband power dividers

Abstract

In this article, we propose a new design methodology to broaden the bandwidth of a multiway Bagley power divider BPD. Single-frequency matching uniform quarter-wave-length microstrip lines in the conventional design are replaced with impedance-varying transmission lines of broadband matching characteristics. The equivalent transmission line model is used for profiling impedance variations, which are governed by a truncated Fourier series. Such variations are determined by finding the optimum series coefficients that result in a wideband matching nature. The proposed technique leads to flexible spectrum allocation and matching level. Furthermore, the resulting structures are compact and planar. First, analytical results of three 3-way BPDs of different fractional bandwidths are presented and discussed to validate the proposed approach. Then, two examples of 3- and 5-way BPDs with bandwidths of 4-10 GHz and 5-9 GHz, respectively, are simulated, fabricated, and measured. Simulated and measured results are in a good agreement, with input port matching of below -15 dB and -12.5 dB for the 3- and 5-way dividers, respectively, over the bands of interest. The obtained transmission parameters of the 3- and 5-way dividers are -4.77±1 dB and -7±1 dB, respectively, over the design bands. The proposed wideband dividers find many applications in microwave front-end circuitry, especially in only-transmitting antenna subsystems, such as broad- and multicast communication links. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:730-738, 2015.