Compact Patch Antenna With Vertical Polarization and Omnidirectional Radiation Characteristics

This communication proposes a compact, low-profile patch antenna with omnidirectional radiation pattern and vertical polarization. A pair of shorted patches are excited in-phase to achieve the omnidirectivity and the vertical polarization, simultaneously. The principle is to excite two back-to-back arranged shorted patches to generate symmetrical electric-field (E-field) distributions normal to the ground plane. Analytical study on how to generate the omnidirectional radiation pattern is carried out. Based on this study, we found that the spacing in between the two patches have little influence on the radiation characteristics, which provides another flexibility in the design. In addition, the shape of the patch and the corresponding field distribution are investigated to further improve the omnidirectivity. To improve the impedance bandwidth, resonant structures are inserted in between the patches, producing the second-order response in frequency. The antenna has been fabricated and characterized, and the measured results are in reasonable agreement with the simulations, showing that the proposed antenna is suitable for potential surface-mount wireless applications.