Application of Mushroom Structure to Suppress Upwarping of Antenna Pattern after Grounding

In this paper, a method of controlling antenna beam by using mushroom structure is proposed for suppressing the upwarping of the antenna pattern after grounding. The proposed antenna is composed of an asymmetric biconical antenna and a ground plane loaded with mushroom structure. We use the characteristics of the mushroom structure beyond the band gap to control the phase of the electromagnetic wave, so that the current distribution on the ground plane becomes concentrated to control the antenna beam. Finally, at 480MHz to 600 MHz, the upwarping of the antenna pattern is reduced by 4° to 8°, and the gain in the maximum radiation direction is increased by 0.11dB to 0.24dB compared to the gain value of the same angle without mushroom structure.