A Novel Dual-Band Omnidirectional Horizontally Polarised Antenna Using Slotted Ground for Wi-Fi Applications

Abstract

This letter explores an innovative approach to designing a compact, dual-band, omnidirectional, horizontally polarised (OHP) patch antenna with a low profile. The antenna’s ground plane is meticulously etched with radial and arch slots to create open-circuited stubs. This design generates two circulating current loops: one beneath the circular patch and the other on the outer side of the circular patch, comprised of four circular stubs. These current loops operate in unison to produce dual-band resonance and in-phase circulating current on the ground at both resonance frequencies. The antenna’s configuration includes four circular stubs formed by printing sequential radial and bent slots beneath the patch. This arrangement generates an omnidirectional radiation pattern in the azimuth plane at the upper resonance frequency. In addition, four open circular stubs outside the patch are integrated into the ground plane cascaded to the inner four stubs to achieve resonance at the lower frequency. The complete dimensions of the proposed antenna configuration are 0.29λ0 × 0.29λ0 × 0.025λ0, with bandwidths of 2.84% and 2.77% corresponding to measured resonance frequencies of 2.457 and 5.27 GHz, respectively. The measured gains are 1.2 dBi at the lower resonance frequency and 0.8 dBi at the upper resonance frequency. Furthermore, the measured roundness of the radiation pattern remains within 1 dB at the lower frequency band and within 2.8 dB at the upper-frequency band.