An Ultrawideband Cylindrical Long-Slot Antenna with Hybrid EBG/Ferrite Ground Plane

On many military tactical platforms, multiple wire-like narrowband antennas are employed, with each antenna covering a specific communication band. This approach enables the adversaries to distinguish the communication center and renders it a high priority target. The cylindrical long-slot antenna architecture can be used as an alternative ultra-wideband antenna to replace the multiple wire structures. To help develop a unidirectional radiation pattern for the long slot array, our group developed a hybrid structure which included the incorporation of EBG/Ferrite ground plane with the long slot array [1]. In this paper, we use the hybrid long slot array structure in [1] to develop a cylindrical ultra wideband array. Computer simulation results for a 10 by 10 cylindrical long slot indicate that the impedance bandwidth for this antenna ranges from 300 MHz to more than 5 GHz resulting in approximately 17:1 bandwidth. The resulting radiation pattern is omnidirectional in the 300 MHz to 2 GHz range. At higher frequencies, and as the azimuth radiation pattern starts to fluctuate because of the non-overlapping element radiation patterns, it is shown that an increase in the number of feed ports overcomes this problem and the array could continue to provide uniform omnidirectional pattern. Simulation results illustrating these radiation pattern results as well as the variation of the input impedance and gain values with frequency are described and discussed.