A metallic patch antenna using a simple short probe for improving impedance match bandwidth

A metallic patch antenna using double-tuned impedance matching is presented in this paper. The antenna mainly consists of a rectangular ground plane, a radiation patch with U-slot and two short metal cylinders, with a size of 200mm×200mm×25.5mm. The two metal cylinders are used to connect the patch and the ground. With the common effects of the U-slot and the two metal cylinders, the impedance match has become better than before. Moreover, high harmonics and cross polarization are suppressed after loading two short pins. Measured results show that the antenna has a wide impedance bandwidth from 830 MHz to 970 MHz (16%) for voltage standing wave ratio (VSWR) less than 1.5, and a high gain level about 9.3dBi in a wide band. A good agreement is achieved between simulated and measured results. Therefore, the proposed metal antenna is a good choice for UHF RFID applications.