Ultra-Wideband Spiral Antenna with Back Lobe Reduction for Communication Systems

Abstract

Spiral antennas are often used for communication applications. However, this antenna has a two-way radiation pattern. The back-lobe antenna can reduce the main lobe transmit power. This article discusses the design of a spiral antenna with a directional radiation pattern. The antenna substrate uses RO4350B with a thickness of 1.524mm and a dielectric constant of 3.66. On the antenna arms, there is a resistive load to extend the bandwidth and reduce the dimensions of the antenna. A balun is used to feed the Archimedean spiral antenna as a balanced antenna. The absorbed cavity is used to reflect the beam in an undesired direction. The simulation results show that the antenna's operating frequency is in the range of 2.5-12.5GHz for a return loss of less than -10 dB. The absorber helps suppress undesired radiation fields and reduces the back lobe of the antenna. In addition, the use of an absorber can reduce antenna gain. Therefore, the thickness of the absorber needs to be considered. The simulation results show the performance of this antenna.