Adaptive Coherent Aperture Combining for small disadvantaged SatCom terminals

Satellite earth terminals with small, sub-meter antenna apertures provide an attractive method for beyond line of sight communications to mobile platforms. Satellite operators frequently classify small terminals as “disadvantaged” because the relatively small, low gain antennas consume a disproportionate share of valuable satellite downlink resources. Small terminal uplinks also typically suffer from limited power and subsequent capacity limitations. Adaptive Coherent Aperture Combining (ACAC) provides an effective solution to the challenges of using small terminals. ACAC combines the energy from two or more antennas, thereby increasing overall signal gain, thus improving the Signal to Noise Ratio (SNR) and Effective Isotopic Radiated Power (EIRP). ACAC differs from a traditional phased array because combining is performed on widely spaced, irregular placed antenna elements. The ACAC employs a unique Blind Source Separation (BSS) algorithm. ACAC performs equally well for both the uplink and downlink. The adaptability of the ACAC combining technique can also be used to mitigate interference from jamming. Since the energy from the antenna elements is optimally combined and not switched, ACAC offers the additional benefits of mitigating blockage and graceful degradation. This paper describes an ACAC application to the small disadvantaged terminal problem, along with tangential technology benefits.