Broadband Filtering Power Divider Employing Hybrid Quarter Circular/Cambered SIW Cavity and MSL Resonators

In this letter, a broadband filtering power divider (FPD) based on a quarter circular/cambered substrate integrated waveguide (QCCSIW) cavity and microstrip line (MSL) resonators is proposed. First, a second-order bandpass filter (BPF) is designed based on the arc-shaped coupling of the QCCSIW. Second, a pair of quarter-wavelength ( $\lambda $ /4) MSL resonators are integrated into the QCCSIW cavity to form a fourth-order asymmetric BPF with a pair of transmission zeros (TZs). Finally, a hybrid QCCSIW and MSL FPD with isolation is investigated. For verification, all BPFs and FPD are simulated, fabricated, and measured. The proposed FPD demonstrates a center frequency of 4.99 GHz, a 3-dB fractional bandwidth (FBW) of 37.11% (1.85 GHz), and an insertion loss (IL) of 0.8 dB. The port isolation is greater than 11 dB within the entire passband. Meanwhile, a pair of TZs are generated at 3.62 and 6.35 GHz respectively. The proposed hybrid QCCSIW and MSL FPD possesses an overall size of $1.73\times 1.74~\lambda _{g}$ , featuring advantages of broad bandwidth, compact size, and superior selectivity.

I. Introduction

With the rapid development of modern wireless communication and radio systems, numerous new challenges have been posed to phased arrays, among which transceiver miniaturization and multifunction are key criteria. Power dividers (PDs) and bandpass filters (BPFs) are two fundamental and independent components. It is crucial to codesign the power divider with a filtering response.