Broadening beamwidth of E-plane radiation pattern of a dipole antenna with loaded monopole elements

Dipole antennas are widely used as the radiating elements of phased array antennas for communications and radar systems. The E-plane radiation pattern of a dipole antenna placed above a ground plane generally has a narrower beamwidth than that of the H-plane. Therefore, it is strongly desired to broaden the E-plane radiation pattern to achieve wide-scanning while keeping gain. A method to broaden the E-plane radiation pattern of a single dipole antenna over a ground plane is proposed, where two parasitic monopole elements with reactive impedance loads are placed in the vicinity of the driving dipole element. Numerical simulations using the EMF method and the method of moments (MoM) are shown to obtain an appropriate value of the reactance and the parameters of the antenna geometry for a broad beamwidth. Experimental results are also shown to demonstrate the broad beamwidth.