A Compact Planar Filtenna for Wireless Communications Applications

Abstract

With the current scenario of emerging services of the wireless communication systems, in addition to the predictable transition from the current wireless communication standards to the new generation with higher operating frequency bands, the need for compact multiband antenna withthe ability of covering the current standards at the microwave band and the next generation standards at the millimeter-wave bandsimultaneously is raising. On the other side, the operation of cognitive radios and self-adaptive systems need todynamically monitor thefrequency spectrum in search of the unused licensed channels and then altering its radiation characteristics for transmission and reception within these spectrum holes as a second user for better exploit the existing spectrum.Such system constraints have forced the researchers to design reconfigurable antennas with ultrawideband mode for spectrum monitoring operation and also have the ability of altering their radiation operating frequency to access the selected unequipped communication channels. Three different types of filtennas are presented in this thesis: fixed, switchable and tunable. In the fixed filtenna a Franklin strip monopole antenna is designed to cover 4G, and wireless applications (WLAN and WiMAX), and a rectangular patch antenna that is designed to cover 5G band. Furthermore, a modified CMRC (compact microstrip resonant cell)low pass filter is printed between the antenna parts to allow feeding the Franklin antenna at low-frequency bands (2.4/5.5 GHz center frequency) while isolating the Franklin antenna from the rectangular patch antenna at the 5G band (28 GHz center frequency).In the switchable filtenna design (second type), theantenna consists of circularly polarized monopole antenna for the UWB mode with twobandpass filters integrated in the feeding