Compact frequency reconfigurable filtennas using varactor loaded T-shaped and H-shaped resonators for cognitive radio applications

Hany A. Atallah, Adel B. Abdel-Rahman, Kuniaki Yoshitomi, Ramesh K. Pokharel

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

In this study, novel compact filtennas with large tunable frequency band are proposed for cognitive radio (CR) applications. Tunability is achieved by integrating a tunable T-shaped and H-shaped bandpass filter with a planar ultra-wideband monopole antenna. The T-shaped filter consists of a microstrip resonator loaded with a stub. The H-shaped filter is composed of two connected microstrip resonators. The proposed tuning technique for both filters is based on centrally loading the stub and the H-shaped with only a single varactor for miniaturisation. Increasing the varactor capacitance results in decreasing the even resonant mode of the resonator without affecting the dominant odd mode. Measurements results show that the proposed T-shaped and H-shaped filtennas are capable of tuning over a wide operating band of 1.68 and 1.73 GHz covering continuous bands for CR communication with 32.9% frequency tuning range (TR) from 4.26 to 5.94 GHz and with 36.7% frequency TR from 3.85 to 5.58 GHz, respectively. Moreover, the radiation patterns are stable over the operating frequency ranges. The frequency characteristics and radiation performance are successfully optimised using 3D full-wave electromagnetic simulator. The fabricated designs are measured for verification purposes. Good agreements are found between simulated and measured results.

Original languageEnglish
Pages (from-to)991-1001
Number of pages11
JournalIET Microwaves, Antennas and Propagation
Volume10
Issue number9
DOIs
Publication statusPublished - Jun 18 2016

All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering

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