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

Abstract

<jats:p>A narrowband dual-band bandpass filter (BPF) with independently tunable passbands is presented through a systematic design approach. A size-efficient coupling system is proposed with the capability of being integrated with additional resonators without increasing the size of the circuit. Two flag-shaped resonators along with two stepped-impedance resonators are integrated with the coupling system to firstly enhance the quality response of the filter, and secondly to add an independent adjustability feature to the filter. The dual passband of the filter is centered at 4.42 GHz and 7.2 GHz, respectively, with narrow passbands of 2.12% and 1.15%. The lower and upper passbands can be swept independently over 600 MHz and 1000 MHz by changing only one parameter of the filter without any destructive effects on the frequency response. According to United States frequency allocations, the first passband is convenient for mobile communications and the second passband can be used for satellite communications. The filter has very good in- and out-of-band performance with very small passband insertion losses of 0.5 dB and 0.86 dB as well as a relatively strong stopband attenuation of 30 dB and 25 dB, respectively, for the case of lower and upper bands. To verify the proposed approach, a prototype of the filter is fabricated and measured showing a good agreement between numerically calculated and measured results.</jats:p>

Design of a Compact Planar Transmission Line for Miniaturized Rat-Race Coupler With Harmonics Suppression

“…In [12], photonic bandgap (PBG) cells have been utilized to design a small RRC with 23% size reduction. Apart from RRC, the PBG has a wide application in other passive microwave devices, such as various types of power dividers, filters, and frequency selective surfaces [13][14][15][16][17]. In [18], an RRC was designed based on defected ground structure technique, eliminating the third harmonic.…”

Compact Double Notch Coplanar and Microstrip Bandstop Filters Using Metamaterial—Inspired Open Ring Resonators

“…However, most of these designs have relatively large size and high insertion losses, because they are based on several elements inserted in series in the propagation line. Examples of these designs include cascaded stepped-impedance resonators [2][3][4], open stubs filters [5], open loop resonators [6,7], T-shaped resonators [8], and cascaded split-ring resonators [9]. Several design techniques for controlling the resonances by means of even and odd mode analysis [10,11], or the frequency response by using an analysis of the transfer function [12,13], have been proposed.…”

Multi‐spurious harmonics suppression in folded hairpin line bandpass filter by meander spur‐line

“…An excellent out‐of‐band characteristic with suppression of spurious bands up to 19 f 0 and attenuation level of 25 dB has been obtained. As an alternative approach, two narrowband (2.12% and 1.15%) dual‐band bandpass filters (BPF) centered at 4.42 and 7.2 GHz with independently tunable passbands of 0.6 and 1.0 GHz respectively has been designed in Reference 17. Two flag‐shaped resonators along with two stepped‐impedance resonators have been integrated in Reference 17 with a bending coupling system to enhance the quality response and to add an independent adjustability feature to the filter.…”

“…As an alternative approach, two narrowband (2.12% and 1.15%) dual‐band bandpass filters (BPF) centered at 4.42 and 7.2 GHz with independently tunable passbands of 0.6 and 1.0 GHz respectively has been designed in Reference 17. Two flag‐shaped resonators along with two stepped‐impedance resonators have been integrated in Reference 17 with a bending coupling system to enhance the quality response and to add an independent adjustability feature to the filter. Accordingly, a good isolation level of 24 dB and strong attenuations of 25 dB and 30 dB in the lower and upper stopbands have been reported.…”