Tunable dual‐mode microstrip patch resonators and filters

Abstract

In this study, tunable dual‐mode microstrip patch resonators are presented and utilised to design microstrip bandpass filters (BPFs). The novelty of the designs lies in that the performance of frequency agility can be realised by using either the signal line or the return path (the ground) of microwave transmission line. For the proposed resonators, the resonant frequencies of two coupled degenerate modes can be tuned using a square‐loop slot with loaded tunable capacitors on the ground plane or on the patch. The locations of the capacitors are determined according to the electric field distributions of the two orthogonal modes. The variations of the modes in spectrum are studied. Finally, two types of demonstration compact tunable BPFs are designed and fabricated, and the simulated and measured results show good agreement.

A compact electromagnetic band gap ground controlled tunable dual mode band pass filter

“…Tunability by this technique is found to be 24% which is 6% more than that of Ref. [6]. Average fractional bandwidth (FBW) varies from 12%-18%.…”

“…In case of designing the microwave filters with frequency tuning many attempts have been made with single mode and dual mode patch resonators [2][3][4][5]. In Reference [6] continuously tunable dual mode patch resonator with capacitor loaded square loop etched slot has been proposed to design the tunable BPF. In this paper an attempt has been made to design a novel compact tunable dual mode circular shaped band pass filter by changing the property of the filter substrate as given in [8].…”

Dual-Mode Microstrip Patch Bandpass Filters With Generalized Frequency Responses

“…Generally, patch BPFs can be designed using arbitrary shape of patch resonator (such as square, circular, triangular resonators, and so on), but the square and circular patch resonators are more desired to be used because they can support dual-mode characteristics [7]- [11]. A dual-mode patch resonator can realize a quasi-elliptic filtering response with two transmission poles (TPs) and two finite transmission zeros (FTZs), which is more advanced than the filter using two coupled single-mode patch resonators.…”

A dual‐mode tunable bandpass filter for GSM, UMTS, WiFi, and WiMAX standards applications

“…Three different types of configurations that have been proposed for implementation of tunable filters are the following: (1) fixed bandwidth with tunable center frequency, (2) fixed center frequency with tunable bandwidth, and (3) simultaneous center frequency and bandwidth tunability …”