Design and Fabrication of Tri-Stopband Bandstop Filters Using Cascaded and Multi-Armed Methods

A Boutejdar,S D Bennani

doi:10.7716/aem.v6i3.524

Abstract

In this paper, we proposed a compact C-open-loop ring resonator and its equivalent circuit. The second cascaded BSF are designed using this simple C-ring resonator. The double ring BPF consists of two cascaded C-ring resonators, which are placed on the RO4003 substrate, while the other triple BSF structure consists of tree cascaded C-ring resonators, which are connected with input and output through microstrip feed lines. The both filters are simulated, optimized and partially realized using MWR simulator and Anritsu E5072A vector network analyzer VNA. In order to reduce the size and to improve the filter characteristics, novel compact filter topologies are designed basing on the previous structures. The proposed multi-band bandstop filters consist of several open-loop ring resonators placed vertically overlapping (coupled multi-armed ring resonator). Using this idea, the filter topologies with design flexibility, close size and excellent results are reached. The novel compact multi-band bandstop filters produce several stopband along a frequency range from DC to 9 GHz, in which each separate band exhibits an acceptable and useful bandwidth. Each stopband has regenerated two reflexion zeros, what leads to a good sharpness factors in the transition domains. Good agreement between the experimental results, full-wave simulation has been achieved. This new filter idea can be very attractive for the nowadays multilayer and compact radio frequency integrated circuit design.

Highlights

In recent years, the demand for compact microstrip filters is increasing due to the recently expanding microwave and mobile communication systems
This cascaded topology shows an undesired increase in the size of the proposed filter
The idea was, the design of filter topology, which consists of several open-loop ring resonators placed vertically overlapping, and to reach filter with design flexibility, close size and satisfactory results

Summary

Introduction

The demand for compact microstrip filters is increasing due to the recently expanding microwave and mobile communication systems. Beside the multi-band operation, low cost, simplicity, small occupied area and performance are desired features for these filters Over these years, microstrip planar multi-band filters have been widely proposed as an approach solution to solving the most difficult technical challenges in microwave and wireless communication areas [1]-[3]. In [15], the coupling of two tri-band dualbehavior resonators DBRs was needed to achieve a second order triple-band filter response with six poles (two poles in each band) and five transmission zeros (single zero between each transmission band and two transmission zeros to the left and to the right of all passbands) This cascaded topology shows an undesired increase in the size of the proposed filter. The comparison between results shows a reasonable agreement between the measured and simulated responses

Basic cell of the compact C-open-loop BSF

Design of the improved cascaded two rings BSF

Distribution of magnetic field at pass-band and stop-band frequency ranges

Design of Dual-band BSF using double-armed open loop resonator

Generalization of the multi-arms technique

Conclusions