This paper deals with the design of new types of ground planes made from low cost, lightweight, and flexible electro-textiles that suppress both edge and curved surface diffraction effects that can degrade the radiation pattern of GNSS antennas.
Electro-Textile Ground Planes
This paper deals with the design of new types of ground planes made from low cost, lightweight, and flexible electro-textiles that suppress both edge and curved surface diffraction effects that can degrade the radiation pattern of GNSS antennas. Two of these are very thin, resistivity tapered textile ground planes that are ultra-wideband and able to operate from 1.1 to 1.6 GHz. Their resistivity profile has been specifically designed to suppress edge diffraction effects; their wide bandwidth makes them particularly suitable for use with multiband GNSS antennas. This ground plane can be sandwiched between plastic cover sheets for weather protection.
The second type is a conformal ground plane designed to suppress curved surface diffraction that affects GNSS antennas used in avionics. It operates as a frequency selective surface with Electronic Band Gap (EBG) characteristics and is able to attenuate antenna backlobes caused by curved surface diffraction from the fuselage of an aircraft. It is designed to operate only over a specific band of frequencies and is very effective when used in conjunction with a “Reduced Surface Wave (RSW)” antenna consisting of an annular ring microstrip patch antenna whose inner periphery is connected to the fuselage of the aircraft.
The RSW antenna is also made from electro-textiles. The performance of this antenna when used with the EBG ground plane has been validated through measurements on a large diameter metal cylinder which simulates the fuselage of an aircraft. The results of these measurements, performed in the GPS L1 band, indicate that when used together they are able to suppress almost all of the antenna backlobe radiation below the horizon. This is an enhancement above the body masking capability of the aircraft fuselage and provides improved protection to the GPS antenna from multipath and interference, especially co-site interference from other antennas located on the belly of the aircraft.
Note: This paper was originally published in the “Proceedings of the 24th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS 2011).