Adjustable compact dual‐band microstrip bandpass filter using T‐shaped resonators

Abstract

In this letter, a compact dual‐band bandpass filter (BPF) is designed, analyzed, and fabricated. A loop resonator loaded by two modified T‐shaped resonators, double T‐shaped resonators, and open bended stubs are applied to form the proposed configuration. The coupling spaces between the loop resonators and open bended stubs result in two passbands with the center frequencies of 2.4 GHz and 5.7 GHz. The LC equivalent circuit of the main resonator is introduced to present an analytical description. Without needing to increase the circuit size, the upper passband can be adjusted between 5.72 GHz and 6.93 GHz. The measured data indicates less than 0.64 dB and 0.76 dB insertion losses in the first and second passbands, respectively. Adjustable second center frequency, compact size, low insertion loss, good suppression level, and a symmetrical structure are the marked features of the proposed BPF. Finally, a good agreement between the simulated and measured results is observed.

A Compact C-Band Bandpass Filter with an Adjustable Dual-Band Suitable for Satellite Communication Systems

“…In [27], a wideband balun BPF was designed using microstrip-to-slot line transition structures and some stub-loaded resonators. To realize a tunable dual-band BPF in [55], a loop structure coupled with bended stubs was loaded by square and T-shaped stubs. It could also be used in LPFs for extending the stopband [56][57][58][59].…”

New design of an adjustable compact microstrip lowpass filter using Z‐shaped resonators with low VSWR

“…Owing to the essential role of microstrip devices in modern wireless communication systems, diverse structures have been suggested to design microwave circuits. Microstrip filters due to their duty in suppressing unwanted harmonics have received more attention 1,2 among which bandpass filters and lowpass filters (LPFs) are at the center of attention.…”

Tunable compact microstrip dual‐band bandpass filter with tapered resonators

“…Compact size, low insertion loss, high attenuation level in the stopband, and sharp roll‐off are the noticeable factors of BPFs designing . Over the last few years, many resonators and filter configurations have been introduced to design high performance BPFs . For example, using ring resonators, different bandpass filters have been designed in Refs.…”

“…Although, these structures have improved the stopband bandwidth, the etched ground of the DGS causes radiation problems and their total sizes are large (considering two layers). There are also a variety of other techniques such as dual‐band resonant junction and λ/2 resonators, U‐shaped stepped‐impedance resonators, single quadruple‐mode resonators, and T‐shaped resonators . In another paper, cross‐shaped coupled lines, half‐circle‐shaped stubs, and stepped‐impedance stub have been combined to reach an ultra‐wideband BPF.…”