Compact Broadband High-Directivity Omnidirectional Stripline Antenna Array

A compact broadband omnidirectional high-directivity stripline antenna array is proposed in this letter. The antenna is made on two layers of substrate and consists of the half-wavelength strip line and the phase inverter. The phase inverter is composed of two pairs of metal via that reverses the phase by 180°. A four-element antenna array is designed. The simulated fractional bandwidth of the antenna is 13.22%, and the simulated peak realized gain is 4.58 dBi. To further enhance the directivity of the antenna, an eight-element antenna array is also designed, with the simulated fractional bandwidth of 12.8%, and the simulated peak realized gain of 6.98 dBi. Finally, the eight-element antenna array is fabricated and measured. The measured results agree well with the simulation results. The measured bandwidth of the eight-element antenna array is 14.34%, and the measured peak realized gain is 6.01 dBi. The proposed compact, broadband, high-gain antenna is an ideal candidate for omnidirectional wireless applications.