Design of high gain omni-directional antenna for suppressing multipath effect

In order to suppress the multipath effect of the antenna pattern on the airborne special-shaped ground, an omnidirectional high-gain vertically polarized antenna that suppresses the multipath effect is proposed. The high-gain antenna is composed of four symmetrically distributed butterfly-shaped electric dipoles units. The dipole arm adopts a gradual structure to broaden the bandwidth. The butterfly-shaped electric dipoles are arranged on both sides of the microstrip floor trace to optimize the out-of-roundness of the horizontal pattern. The feeding phase of four vertically distributed butterfly-shaped electric dipoles is set to reduce the multipath effect caused by the ground, thereby suppressing the multipath effect. According to the theoretical analysis and electromagnetic simulation calculations, the optimal structure of the antenna and the phase difference of the unit feed are determined, and simulation and measurement have been carried out. The measurement results show that when the phase difference of the four units is 25° under the constrained size, the multi-path zero depth caused by the y-axis ground can be effectively suppressed, and the measurement results are in agreement with the simulation results. The proposal of this antenna provides a solution to suppress the effects of multipath for high-gain antenna arrays installed on special-shaped ground.