Low-Profile on-Board Antenna With a Broad Beam Based on Three-Current Model

A low-profile three-current model is proposed to guide the design of an on-board antennas with a broad beam. Based on this model, an on-board three-element antenna is designed. When the side length of the ground is infinite, the 3-dB beamwidths in the xz plane and yz plane are all 180 ◦ , and the radiation pattern in the xy plane has a gain fluctuation less than 3 dB. When the side length of the ground is 2λ, the measured 3-dB beamwidths in the xz plane and yz plane are 141 ◦ and 148 ◦ , respectively. A quasi-hemispherical radiation pattern can be obtained based on the proposed