Compact Reconfigurable Antenna with Frequency and Polarization Agility for Cognitive Radio Applications

Abstract

As technology develops, it is CR systems that now offer a way for underused frequency bands to be accessed, suitably filling the available spectrum. In order to take advantage of CR technology, agile antenna systems are required to alter their features in real-time. This paper shows how a compact adaptive antenna was designed and how it was tested for both frequency and polarization agility for use in cognitive radio applications. The suggested antenna uses PIN diodes and varactor tuning elements to help tune its frequency both discreetly and continuously within the range of 1.8 to 3.5 GHz. Its coverage of GSM, LTE and WiMAX means the antenna can be used in many areas without switching to another model. Polarization agility is accomplished with RF switches that directan advantage of the different polarization modes and prevent interference from incorrect polarization effects in different environments. The antenna is built on FR4 and measures only 30 mm by 35 mm. It includes a slot-loaded patch and a partially reconfigurable ground plane to improve the antenna’s bandwidth and radiation qualities. Proper simulation of the antenna in CST Microwave Studio and physical measurements with a vector network analyzer and an anechoic chamber proved that it maintains constant radiation, has a maximum gain of 4.5 dBi and its radiation efficiency in all reconfigured states is higher than 85%. Due to its dual-agility, the antenna is able to support various spectrum usage, flexible channels and polarization and as a result, it can be considered for use in new CR transmitters and wireless communication tools.