Performance Evaluation of a Membrane Waveguide Array Antenna

NASA Langley Research Center (LaRC) has pursued the development of tensioned membrane antenna technology for several years. For many applications, it is desirable to have space-based antennas which are very large. As the physical size increases, antennas constructed of conventional materials quickly become too bulky and heavy to be practical for space applications. For some of these applications, such as earth remote sensing, reducing electromagnetic losses in the antenna is also critical. For this reason, there is interest in finding new methods of fabricating large antennas which not only exhibit lighter weight than conventional antennas, but also meet stringent electromagnetic performance criteria. One configuration which has been investigated by NASA LaRC is a slotted waveguide array antenna constructed of a metallized thin membrane material. Several test articles have been built and tested to validate this configuration. This concept will lend itself to compact packaging for launch, and can be tensioned on an inflatable, rigidizable support structure, which would deploy once on orbit. One major advantage of this planar configuration is that there is no need for fabricating a doubly curved surface (such as for a reflector antenna) from membrane material. One of the most challenging technical issues to be faced in constructing antennas such as the ones described above is that of designing the antenna and feed network to minimize electromagnetic losses while maintaining compatibility with a light, thin, membrane structure. This paper describes the electromagnetic evaluation of an eight element metallized membrane L-band waveguide array antenna with an integrated membrane feed network. Though there are still some technical hurdles to overcome before this technology is applicable for earth remote sensing from space, the result of the performance evaluation shows that further investigation is warranted.