Low-profile radio antennas are needed due to circumstances such as limited antenna locations and height requirements. A patch antenna is a type of radio antenna with a low profile that can be mounted on a flat surface. Due to the low-profile nature of patch antennas, they can be mounted on the exterior of aircrafts or spacecrafts and incorporated into robotics.
Common patch antenna shapes are square, rectangular, circular, and elliptical but any continuous shape is possible. For extreme conditions, such as in outer space, a patch antenna is needed that can handle extreme temperature swings.
NASA Goddard Space Flight Center developed the Toroidal Radiation Pattern Patch Antenna, which has a low-profile configuration with an omnidirectional radiation pattern. Since the antenna has a toroidal shape, it can transmit radio signals in all directions at an equal radio power. Compared to a center-fed circular patch antenna, the Toroidal Radiation Pattern Patch Antenna has a large bandwidth and similar radiation pattern as well as an annular ring. The distance between the patch and the ring can be modified, resulting in different operation bandwidths. The annular ring operates at 5.3 GHz and 5.8 GHz WiFi bands to meet International Space Station requirements.
A typical patch antenna consists of an antenna element bonded to a dielectric substrate, such as a printed circuit board, with a continuous metal layer bonded to the opposite side of the dielectric to form a ground plate. The new antenna utilizes a dielectric that can handle temperature swings necessary for deployment in space, having minimal thermal expansion. It also contains a protective dome to protect it from extreme conditions.