High performance LPF with negligible group delay using circular resonator and transfer function analysis

In this article, an adjustable microstrip lowpass filter(LPF) with the cut‐off frequency (fc) at 1.59 GHz is designed and fabricated. The proposed structure is composed of a Z‐shaped resonator as basic resonator and a combination of modified T‐shaped and Z‐shaped resonators as suppressor units. To describe a theoretical design, the L‐C equivalent circuit of the basic resonator and also its transfer function are calculated precisely; then, the location of the first transmission zero (TZ) is accurately computed. Generating a deep TZ near the cutoff frequency leads to a high roll‐off rate of 195 dB/GH. The LPF also benefits from an extremely wide stopband from 1.72 to 23.67 GHz (15 fc). In passband region, the insertion loss and return loss of the LPF are 0.62 and 22.9 dB, respectively. The experimental results also show that maximum variation of group delay is only 0.53 ns regarding a negligible figure. The electrical size of the LPF is 0.187 × 0.083 λg2 (where λg is the guided wavelength at 1.59 GHz). Finally, the proposed LPF achieves a high figure of merit of 57 860 deemed a great accomplishment.

Section: Measurement Results and Discussionmentioning

confidence: 99%

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

Pahlavani

Moradkhani

Sayadi

2020

“…In the last decade, researchers have concentrated on using bandpass filters [8][9][10][11][12][13] and lowpass filters [14][15][16][17][18][19][20][21] as an effective method to produce a high-performance Gysel power divider. In refs.…”

Section: Introductionmentioning

confidence: 99%

Design and fabrication of a miniaturized Gysel power divider using improved T‐shaped resonator

Pahlavani

Moradkhani

Sayadi

2022

A high-performance Gysel power divider showcasing high suppression factor and low insertion loss at 540 MHz has been designed, investigated, and fabricated in this paper. The proposed Gysel power divider is made up of replacing six identical resonators with conventional transmission lines. The proposed resonators, which have been analyzed using LC equivalent circuit analysis, are designed to have a small size, low insertion loss, wide stopband, and narrow transition band. The final tested results have indicated that the suggested power divider is able to suppress nine harmonics; moreover, it has only an insertion loss of 0.4 dB. Another positive feature of the power divider is its small size in comparison with a conventional power divider at this operating frequency, where it occupies 34.5 × 63.8 mm 2 equaling to 0.188 × 0.102 λ g 2 , where λ g is the wavelength guide at 540 MHz. This figure is 25% of a conventional Gysel, considered as a remarkable point.

“…In Reference 8, a LPF with ultrawide stopband consisting of three basic circular sectors, two smaller quadrants, and a number of high‐impedance lines is developed, but it suffers from large insertion loss. In Reference 9, a high performance microstrip LPF is proposed by exploiting a circular resonator as a main resonator. However, it does not have the advantages of low cost and self‐packaging.…”

Section: Introductionmentioning

confidence: 99%

Design of wide stopband lowpass filter using transformed radial stub based on substrate integrated suspended line technology

Zhang

et al. 2020

A novel planar elliptic function lowpass filter (LPF) based on substrate integrated suspended line technology is developed and investigated. Transformed radial stub, stepped‐impedance resonators, and open stubs are cascaded to obtain sharp roll‐off and wide stopband. The proposed LPF produces six transmission zeros in the stopband, and the mechanism of the transmission zeros is studied. Both the simulation and measurement are conducted to verify the performance of the proposed filter, and good agreement between the simulated and measured results is observed. The filter shows attractive characteristics such as low insertion loss<0.6 dB, high return loss of 20 dB, wide stopband from 3.85 to 24 GHz with −20 dB attenuation level and a small area of 0.20 λg × 0.14 λg, where λg is the waveguide length at the cutoff frequency.