Abstract
This work proposes a design of compact filter-antenna with fixed and frequency-agile bands for wireless communications and cognitive radio (CR) systems. The filter-antenna is realized by attaching a bandpass filter with an independent fixed band and a tunable band to a UWB antenna. The dual bandpass filter consists of a folded open loop resonator loaded with single varactor diode at a suitable location to achieve reconfigurability operations for the high band while the low band remains fixed at 4.5 GHz. A reconfigurable broadband frequency range of 3.2 GHz from 7.8 to 4.6 GHz is achieved for the high band by changing the capacitance of the varactor from 0.16 to 2.25 pF, respectively. A prototype of the filter-antenna is fabricated and measured at a selected capacitance of 0.6 pF to verify the simulation results. Good agreements between simulated and measured results are obtained.
Highlights
Recent advancements in wireless communication systems and the growing request for frequency bands have caused congestions in the available electromagnetic (EM) radio frequency (RF) spectrum
Accessibility of various unlicensed bands in the crowded RF spectrum and compatibility of wireless devices with different standards represent the main objectives of current communication systems to operate with dual frequency bands [1], [2]
The filter-antenna is realized by attaching a tunable bandpass filter to the feed line of a UWB antenna
Summary
Recent advancements in wireless communication systems and the growing request for frequency bands have caused congestions in the available electromagnetic (EM) radio frequency (RF) spectrum. Achieving wide tuning ranges with steady radiation patterns are challenging features because of the matching problems and the switching devices limitations In these systems, printed slot antennas have gained significant consideration due to their wideband matching characteristics and omnidirectional radiation patterns [9], [10]. They suffer from matching problems when converted to single tunable band operations with wide tunability range. A dual band filter-antenna with fixed and frequency-agile bands for wireless communications and CR applications is presented and discussed. A summary of the work is summed up
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