Wideband semielliptical monopole antenna

A printed semi-elliptical monopole fed by a grounded coplanar waveguide is investigated as a low-profile, light-weight, wideband radiator. Two methods of improving the impedance match at higher frequencies without increasing the occupied volume are reported. The first method utilizes a semielliptical stub at the feed point, while the second involves modifying the radiator to conform to a triple elliptical profile. It is shown that a bandwidth of more than 17~1 (V SWR <; 2.1) can easily be achieved in a compact volume of 0.108λ₀ × 0.336λ₀ × 0.002λ₀, where λ₀ is the free space wavelength at the minimum operating frequency of 813 MHz. Plated through holes are used to suppress the excitation of undesired modes which can arise due to the parallel ground planes. A parametric study on the topology and dimensions of the radiator and the feed section is presented, and a design tradeoff space is established. The predicted performance of the proposed antennas is verified experimentally by fabricating three prototypes. The impedance bandwidth, radiation patterns, and gain of the prototype antennas are presented and are found to be in good agreement with simulated results. The developed antennas are well suited for applications where a wide bandwidth, small footprint, low profile, and light weight are required.