Broadband body‐worn antenna using a top‐loaded pyramidal radiator. Issue 4 (10th February 2020) - Jackson, Brad R.
Abstract : A wide‐bandw idth low‐profile quasi‐omnidirectional antenna is presented and experimentally demonstrated when integrated with a helmet for emergency services or military applications. The antenna consists of a pyramid‐shaped radiator that is top‐loaded with an etched copper‐clad microwave laminate with two shorting strips used to improve the input impedance matching, particularly for lower frequencies. The design and operation of the antenna are first introduced using a flat ground plane, and then experimental results are reported when it is installed on a helmet where the outer surface of the helmet is used as the ground plane. The results show a very wide impedance bandwidth from 890 MHz to 13.7 GHz (VSWR ≤ 3) and predominately monopole‐like radiation patterns up to ∼ 11 GHz. The antenna has a height of λ /16 at the lowest operating frequency of 890 MHz (21 mm). Simulation results with a human body model demonstrate the significantly improved omnidirectionality of the proposed helmet antenna compared to more conventional body‐worn antennas used in some applications.