Table of Contents
International Journal of Microwave Science and Technology
Volume 2016, Article ID 9460823, 10 pages
http://dx.doi.org/10.1155/2016/9460823
Research Article

Reconfigurable and Tunable Filtenna for Cognitive LTE Femtocell Base Stations

National Institute of Posts and Telecommunications (INPT), 10100 Rabat, Morocco

Received 15 March 2016; Revised 16 May 2016; Accepted 17 May 2016

Academic Editor: Chien-Jen Wang

Copyright © 2016 Hamza Nachouane et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A single-port uniplanar antenna with a built-in tunable filter is presented for operation in multiple LTE bands for cognitive femtocell applications. The antenna is based on a monopole microstrip patch fed by coplanar waveguide. The frequency reconfigurability is achieved by using two PIN diodes to couple or decouple a ring slot resonator filter from the antenna feed line. By switching the PIN diodes, the proposed design can operate in either wideband or narrowband modes. When the antenna operates in the narrowband state, two varactor diodes are used to continuously tune the narrowband frequency from 2.55 to 3.2 GHz, while the wideband state is obtained over the 1.35–6.2 GHz band. The diodes and their biasing networks have nearly no severe effect on the antenna characteristics. Prototypes of the proposed structure using ideal and real switches, with and without varactors, are fabricated and tested. Measured and simulated results are in good agreement, thus verifying the good performance of the proposed design. The obtained results show that the proposed antenna is very suitable for cognitive radio applications, in which the wideband mode is used for spectrum sensing and the narrowband mode for transmission at different frequency bands.