Fabrication and testing of the COMWIN vest antenna

Man-carried antennas usually identify the radio operator in a squad. The antennas are often whips that are narrowband and tailored to a particular radio. The Joint Tactical Radio with a frequency range from 2 MHz to 2 GHz presents new requirements. Incorporating the antenna into the uniform will hinder identification of the radio operator. A prototype of an antenna in the form of a Vest is part of the Combat Wear Integrated (COMWIN) Antenna System. The COMWIN vest antenna was fabricated and tested at the SPAWAR Systems Center. The design was proposed and analyzed theoretically by researchers at the Naval Postgraduate School. Impedance measurements showed close agreement with the theoretical predictions. The calculations had predicted a resonance at 95 MHz and a relatively constant impedance for higher frequencies. When a person wore the vest, the frequency of the resonance decreased to 65 MHz and the maximum impedance decreased by a factor of 4. When a transformer was inserted into the circuit, the measured VSWR was less than 3.1:1 for all frequencies between 100 and 500 MHz. Radiation patterns compared favorably with the predictions. The pattern is isotropic and vertically polarized for frequencies less than 250 MHz. For these frequencies there is a minor null in the elevation pattern at an angle of 30°. Most of the energy is directed towards the horizon. Research into the COMWIN vest antenna capable of transmitting or receiving at all frequencies between 30 and 500 MHz is planned. The radiation hazards of using this technology is assessed and mitigated