Proposal and design of an end-fire slot antenna with low back-lobe and improved front-to-back ratio

摘要

This paper has proposed an end-fire slot antenna with back-lobe level suppressionand front-to-back ratio (FBR) improvement. At first, the radiation characteristicof the conventional λ/4 slot antenna are meticulously investigated toinitially demonstrate that its FBR can be maintained as high as about 6 dB.Then, the antenna under three different boundary conditions is deeply studied.The results reveal that the currents along the two sides of the metal ground areparallel to the slot radiator, resulting to affect the back-lobe radiation level to agreat degree. As such, a pair of rectangular slots is properly etched on the twosides of the metal ground for further reduction of back-lobe radiation level andFBR improvement. Finally, a prototype antenna operating at 4.7 GHz isdesigned and fabricated. The measured results demonstrate that the back-lobeis indeed greatly decreased as predicted and the measured FBR of the proposedslot antenna exceeds 25 dB, where an increment of about 19 dB than the conventionalλ/4 slot counterpart is successfully obtained, thereby evidentlyexhibiting better end-fire radiation performance.