JoWUA

Abstract

This paper discusses the electromagnetic design and optimization of a compact, nested triangular complementary microstrip bandpass filter (BPF) for multiband communication applications. Multi-resonant characteristics and strong stopband performance are attained using nested triangular open-loop resonators manufactured on Rogers RO3003 (εr = 3.0, h = 1.52 mm, copper = 35 μm). Full-wave electromagnetic simulations that were done on AWR Microwave Office showed that there are four primary passbands at 5.31 GHz, 9.14 GHz, 10.0-10.66 GHz and 12.91 GHz. The principle passband BPF achieves very good impedance matching, showing S11 ≈ −39.7 dB and for the ultralow S21 ≈ −0.07 dB there is an insertion loss. There are multiple sharp transmission zeros, one of which is located close to 9.136 GHz due to a mixture of the electric and magnetic couplings. Because of that, they achieved significant out-of-band rejection. The designed filter compactly occupies an area of about 0.04 λg × 0.04 λg, which displays a higher level of miniaturization compared to the tri- and dual-band designs that are known. Effective tuning of the center frequencies, bandwidths and transmission zeros can be made using parametric sets of resonator dimensions, gap size changes and coupling modifications. Insertion loss, return loss, fractional bandwidth, group delay, and VSWR are some of the most important performance metrics that were evaluated and compared to previous works to demonstrate the improvements in performance and area reduction. This unique nested triangular configuration of CSRRs ultimately gives rise to an optimally compact, selectivity, low-loss technology suited for WLAN, X-band, Ku-band, and other multiband wireless systems.