A High-Efficiency Broadband Omnidirectional UHF Patch Antenna Applying Surface Plasmon Polaritons for Handheld Terminals

In this letter, a high-efficiency broadband omnidirectional UHF patch antenna applying surface plasmon polaritons (SPPs) for handheld terminals is proposed. Corrugated metallic strip is used to work as SPPs to efficiently forward transmit electromagnetic wave for better power flow distribution on the surface of the SPPs strip. A loading spilt SPPs ring wrapping the spiral lines and patch is introduced, which compensates the phase and changes the power flowing direction for bettering its omnidirectional performance. A prototype is fabricated and tested. The measured results show a good omnidirectional radiation pattern in the H-plane and 84°-112.5° of a 3 dB beamwidth in the E-plane. Its available impedance bandwidth (|S
₁₁
| <; -10 dB) is about 10% ranging from 302 to 335 MHz. The realized gain over this bandwidth ranges from 0.9 to 1.76 dBi, and the simulated results show that its radiation efficiency is greater than 90%; the peak value can reach 98.7%. The overall size of this antenna is 230 mm × 65 mm × 1 mm (0.23 λ
₀
× 0.065 λ
₀
× 0.001 λ
₀
) at 302 MHz. This high-efficiency antenna with balanced broad band, high gain, wide beam, and miniaturization can be easily applied to UHF band mobile terminals.