M-shape electromagnetic-bandgap structures for enhancement in antenna performance

Design of circular annular ring patch with circular polarization for surface wave suppression by embedding electromagnetic band-gap structures in its ground plane is considered. The ground plane consists of an M-shaped EBG structure inscribed in the unit square metal patch of dimension 6 mm × 6 mm with conducting vias located at centre of each EBG cell. The antenna is first designed as a simple circular annular ring patch without EBG and then in a planar and double layer form with EBG to resonate at centre frequency of 2 GHz. The circular annular ring patch when surrounded by two rows of M-shaped EBG structure shows improvement in the antenna performance parameters such as impedance bandwidth, axial ratio bandwidth and gain, in comparison to antenna without EBG structures. The circular polarization purity is excellent over the stop band of 296.2 MHz for the M-shape EBG structure. The maximum co-polarized gain is 6.77 dB and cross-polarized gain is −12.55 dB for main lobe direction. The proposed double layer antenna with M-shape EBG structure embedded in its ground plane can be a good candidate for the Mobile Satellite Service band (1990–2025) MHz and for UMTS, WCDMA (1920–2170) MHz applications.