An alternative feed design for the MRO antenna

NASA´s Mars Reconnaissance Orbiter (MRO) (see http://marsprogram.jpl.nasa.gov/mro/), scheduled for launch in 2005, is intended to study the history of water on Mars. The current feed design for the 3-meter reflector antenna uses a dielectrically supported disk-on-rod Ka-band (32 GHz) feed in the center of an X-band (7.2 GHz, 8.4 GHz) corrugated horn. As a potential backup design in case of problems, an alternate feed design for the MRO antenna that does not use any dielectric materials or a disc-on-rod was developed. The design uses a Ka-band Potter horn in the center of the current X-band MRO corrugated horn. Using the same high-gain reflector assembly, the new feed provides virtually the same X-band gain (within 0.1 db) and more than 1 dB improvement at Ka-band.