Open slot antenna in a small ground plane

The impact of a finite ground plane on an open-slot antenna performance is reviewed and the far-field pattern behaviour is clarified. The pattern of this slot configuration is fundamentally different to its complementary dipole. Here, a parametric study of a slot antenna is presented including the impact and use of a small groundplane with different sizes and bending angles along the slot axis. As a result, the authors demonstrate a simple, effective antenna comprising a slot in a small groundplane, which has direct matching to 50 Ω, high efficiency and medium gain over a wide bandwidth. The slot length at the second resonance dictates the centre frequency, and the slot width influences the bandwidth. Only a small groundplane is required to maintain the performance. The impedance is also insensitive to the groundplane bending angle from 180° (flat) down to 30°. This bent groundplane configuration allows some control over the front-to-back ratio, and thence the directivity.