Compact, two-element array with high broadside directivity

A combination of two high directivity, electrically small, slot-modified conducting disc-augmented Egyptian axe dipole (EAD) antennas is investigated to achieve interesting broadside radiation properties, including a high broadside directivity and front-to-back ratio. Their array arrangement is guided by a simple two-element dipole model. The parasitic conducting disc associated with each EAD antenna is modified only slightly from their original single-element dimensions to preserve nearly complete matching to their sources, to accommodate the coupling between the two elements and to maximise the array pattern characteristics. Parameter studies lead to a final design, whose simulation results demonstrate that the two-element array has outstanding performance characteristics, including a 9.98 dB broadside directivity, an 88.19% radiation efficiency, a 20.03 dB front-to-back-ratio, a -22.42 dB mutual coupling level, more than a 30 dB level of polarisation purity, and good impedance matching to their respective 50 Omega sources, despite each antenna being electrically small, that is, ka < 1, and the distance between the centre of each element being only slightly larger than a half wavelength.