Reconfigurable Antennas of Wide Tuning Ranges and Controllable Selectivity Using Matching Networks

Abstract

In this chapter, a novel design method was proposed for reconfigurable antennas, independent of the geometries and the dimensions of the antennas, providing wide tuning ranges and controllable selectivity. A simple, unspecified S-UWB antenna can be attached to a feeding network to form one integrated selective and reconfigurable antenna. Through the design of tunable wideband matching network, a simple modified ultra-wide band (UWB) antenna can be reconfigurable and re-operated in different bands over a wide of ranges. Based on UWB antennas with proper Tor π-shaped matching network designed in frequency domain, the receiving antennas can be switched to specific bands or even multiple bands continuously. Most of the multiband antennas need complicated approaches to control bandwidths and lack of tuning flexibility. However, the design principles and the controlling mechanism based on microwave circuit theorems are relatively simple, so different fractional bandwidths from 5% to 20% can be feasibly implemented in our proposed architecture. Therefore, the parameters for the antenna operation bands and bandwidths can be calculated and estimated in a straight forward manner. The L-, Tand π-network are chosen for examples to demonstrate the performance in simulation and in implementation. The simulation results show that the proposed antenna can cover from 1.8 GHz to 11.5 GHz with bandwidth ~300 MHz. Replacing the Ltype with a T-type or π-type network which gives one more variable freedom to achieve high selective reconfigurable antenna of 80 MHz bandwidth. By utilizing special designed tuning inductors, the antenna bandwidth can be further controllable. The simulation results show that this proposed antenna can switch to 1.8, 2.45, and 3.5 GHz with bandwidths from 80 to 400 MHz. The proposed antenna architecture provides a reconfigurable RF front end for transmission and reception. Such high flexibility can enable antennas to operate in varying environments for biomedical applications and different bands and thereby, make antennas applicable to wireless body area network (WBAN) as well as multi-mode/multi-band commercial applications. The novel circuitry antenna (modified UWB antenna combining with feed matching components) approach expands the flexibility and the bandwidth for multiband communication systems in a simple implementation. Reconfigurable multi-band antennas have drawn attentions for modern heterogeneous communication systems, such as antennas for quad-band cellphones, Software-defined