A half-space covered antenna for air-ground communication

Abstract

In this paper, a half-space covered antenna with horizontal right hand circular polarization (RHCP) property is presented, which is realized by perpendicular slot pairs cut on the outer conductors of one coaxial line; To cover the null of the radiation pattern in the boresight direction, we draw out the inner conductor of the antenna and make it into a helical shape. As a transition between the slot array and the helix structure, the semi-spherical outer conductor is also cut with slot pairs. It is noted that for air-ground communication, the attenuation of electromagnetic waves in horizontal plane is much larger than other directions and the greater the deviation from this plane, the smaller the attenuation. The presented antenna is designed to compensate the attenuation difference in different elevation angle. It has a bandwidth of 12.5% for return loss > 10 dB and has a bandwidth of 7.5% for axial ratio < 3 dB.