A compact reconfigurable bandpass/lowpass filter with independent transmission zeros based on generalized NRI metamaterial

Abstract

This article introduces a new design and analysis of a compact reconfigurable bandpass/lowpass filter based on compact negative refractive index metamaterial transmission line. The filter equivalent circuit has been designed as a cascade of three cells of bisected-Π/Π configuration. The reconfigurable function was achieved using inserted switches in ON and OFF modes within the cells. The filter works as bandpass when all switches are in ON condition and for lowpass switch-1 is in OFF and switch-2 in ON condition. The low pass filter has 3-dB cutoff frequency of 3.25 GHz with a selectivity of 170 dB/GHz. The bandpass filter is cantered at 3.65 GHz and has a well-matched pass band with insertion loss of 0.2 dB and wide stop band with two transmission zeros (TZs). The frequency positions of TZs are independently varying with series and shunt loading elements.The filter performance has been validated through circuit model, electromagnetic simulation, and experimental measurements. The electrical size of bandpass filter excluding feed line is 0.22 λ g × 0.20 λ g (12 × 11 mm 2 ) at center frequency of 3.65 GHz and for lowpass filter is 0.19 λ g × 0.18 λ g at cutoff frequency of 3.25 GHz. The filter can be applied in suitable for different wireless applications. K E Y W O R D SECRLH, generalized negative refractive index, reconfigurable filter

Novel configuration of ultra‐wide band uni‐planar configuration of complementary split ring resonator composite right/left‐handed based band pass filter with sharp roll off and good stopband attenuation

“…Many CRLH cells are used for UWB filtering applications 21‐26 . Some of these works are only CRLH based design as in 23‐25 . While, following the same procedures of our work, 21,22 CRLH BPF has been employed in combination with other filtering techniques to reach the desired result.…”

“…To clarify the compactness of the UWB CRLH filter, other CRLH filters characteristics are compared with the proposed one. Many CRLH cells are used for UWB filtering applications 21‐26 . Some of these works are only CRLH based design as in 23‐25 .…”

“…CRLH transmission line has a negative refractive index and hence it has unusual properties that lead to ultra‐size reduction and wideband functionality of microwave components 19,20 . One of the most common applications of CRLH TL is compact low pass filter (LPF) and BPF 21‐24 and mainly ultra‐wideband BPFs 25‐29 . In addition, the Epsilon negative (EN) structure can demonstrate a bandstop property due to its achieved imaginary propagation constant 30,31 .…”

Miniaturized quad‐band filter with improved selectivity using split ring resonators and metallic strips

“…A compact bandpass and lowpass filter have been designed by cascading of three cells of bisected pi configuration which interdigital capacitor and stubs. 14 Quad-band filter with wide stopband restriction has reported in Reference 15, by using skew-symmetrical coupled asymmetric stepped impedance resonators. In Reference 16, a quad-band filter with a third-order filtering response in each passband is synthesized by a fourstage stepped impedance resonator.…”

An Intrinsically Switched Tunable CABW/CFBW Bandpass Filter

“…To adapt to complex operating environment, reconfigurable filters with switching capability have aroused a wide attention recently. By using the pin diodes as switches, the proposed filters in [10][11][12][13][14] can be operated in four states. Through utilizing combinations of pin diodes and varactors, the center-frequency-tunable filters can be switched in on/off state or in high/low passband [15,16].…”