A Low-RCS Wearable Planar Monopole Antenna Based on Phase Cancellation

In this paper, a wearable planar monopole antenna (PMA) with low radar cross section (RCS) for very high frequency (VHF)/ultra high frequency (UHF) communications is proposed. The antenna consists of a blade-like radiator and a coplanar waveguide feed, both of which are totally composed of two types of metallic units connected with each other so that the antenna can radiate and achieve RCS reduction by one and the same structure. In order to realize cancellation of the reflected electric field level based on phase cancellation principle, the two units are designed and optimized to produce a reflection phase difference of nearly 180° and are arranged into a checkerboard configuration. Since the antenna will be integrated with a vest to be worn on the back of a human body, woolen textile and body tissue are considered to serve as its substrate. Taking the practical fabrication condition into consideration, the polyimide substrate of 0.1 mm thickness is also used to simulate the flexible printed circuit board. Through simulation experiments with CST Microwave Studio, radiating performance and RCS of the designed antenna and an equal-sized PMA with complete metallic surface are compared. Results show that the designed antenna has an omnidirectional radiation pattern in the operating frequency band of 108-512 MHz and 8 dB RCS Reduction is achieved from 8.0 to 10.0 GHz under normal incidence of plane wave.