A Lens Antenna with Earth Shaped Beam for Low Earth Orbit Satellite Application

This paper proposes a new design of a lens antenna for low Earth orbit (LEO) satellite data transmission. The lens antenna achieves approximately equal power density over a wide angle for radiation to the ground. The antenna is a mushroom shaped lens fed with a circularly polarized (CP) waveguide antenna. The CP waveguide antenna employs a pair of radially grooves to generate circular polarization and a corrugated groove for expanding the beam width. The mushroom shaped lens reforms the initial beam from the waveguide antenna into the target beam to produce a radiation with quasi-equal power density at different locations on the Earth's surface. The lens antenna achieves a return loss higher than 15 dB and an axial ratio lower than 3 dB over the band of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$8-8.4 \text{GHz}$</tex>. The antenna beam takes on a shape of lower in the middle and higher around, which exhibits the advantage of compensating for different path losses between the satellite and the ground user in different positions on earth. The proposed antenna shows great potential for satellite communication application.