Continuously Tunable Dual-mode Bandstop Filter

TL;DR

This paper presents a varactor-based dual-mode bandstop filter with continuous tunability from 0.66 to 0.99 GHz, implemented in microstrip technology, offering a compact design and adjustable frequency response.

Contribution

It introduces a novel varactor-tunable dual-mode bandstop filter with a continuous tuning range, fabricated using planar microstrip technology, enhancing flexibility and miniaturization in RF filtering.

Findings

Achieved a continuous tuning range of 0.66 - 0.99 GHz.

Demonstrated a compact size of 0.12λg x 0.16λg.

Validated the filter's performance through prototype measurements.

Abstract

A varactor-based tunable bandstop filter has been proposed in this article. The proposed filter is based on a dualmode circuit developed by introducing inductive and capacitive couplings into a notch filter. The frequency tunability is achieved by using varactor diodes instead of the lumped capacitors in the circuit. Next, the equivalent circuit model has been implemented in planar microstrip technology using thin inductive traces and varactor diodes. The fabricated filter prototype shows a continuous center frequency tuning range of 0.66 - 0.99 GHz with a compact size of 0.12lg*0:16lg, where lg is the guided wavelength at the middle frequency of the tuning range.