The influence of phased-array antenna systems on LEO satellite constellations

In this era of low earth orbit (LEO) satellite constellations, the phased a rray has become the antenna implementation of choice. Previously thought to be an expensive solution for satellite systems, the requirement to provide multiple beams makes the phased-array antenna implementation a modest cost on a per-beam basis. Selecting a phased-array antenna for the satellite sy stem based on cost/performance influences the satellite and constellation d esign in a manner that is not so obvious. This influence is primarily a fun ction of scan loss (reduced performance at angles off boresight), which is not a significance factor in more limited-scan, parabolic-reflector antenna systems. Antenna system cost and performance (as influenced by scan loss) are significantly affected by satellite and constellation parameters, inclu ding the antenna system boresight, the preferred altitude of the satellite constellation and, lastly, the optimum number of satellites in the constell ation. Propagation effects due to min and, consequently, the allocated freq uency band, further enhance the effects of scan loss and compound this infl uence on constellation size. This influence is most significant at K-band a nd above.