User terminals with multipaneled phased arrays and omnidirectional antennas applied in an elliptical medium Earth orbit satellite communication system for the Arctic

Increased focus on secure communications has created a growing interest in national and regional satellite systems. An elliptic medium earth orbit satellite system for Nordic/Arctic areas is proposed and investigated. Three satellites in a single orbital plane will provide continuous coverage. New technology, digitizing radio signals at radio frequency (RF), digital phased-array antenna steering and digital combining of multiple antenna panels make efficient and low-cost implementation of high-performance user terminals possible. The satellite orbits are simulated to define the distribution of elevation, azimuth, and variation of path distances for sites in the focus area. The distributions are input to a performance analysis of the user terminal antenna solution. For the S-band, an electronically steered multipaneled antenna, denoted as a five-panel frustum configuration, is proposed and analyzed for fixed-site installations and installations on a moving ship. With a panel size of 20 cm × 20 cm, the antenna is compact, small, and has room for four antenna elements at 2 GHz. The configuration shows good performance for all satellite azimuths and elevations. In this concept, one antenna panel of five is active, the maximum scan loss is 1.2 dB, and the total gain, including element gain, array gain, and losses, is estimated to be ≈ 9–12 dBi in practical implementation. In an advanced concept, co-phasing and combining 3–5 simultaneously active panels, there is a potential for a gain increase to ≈14−17 dBi. Analysis shows excellent robustness against angular movements on a ship’s platform up to a tilt of 10°. Important propagation issues related to ship-to-satellite communication, such as ionospheric attenuation, scintillations, reflections, and scattering from the sea surface, are analyzed. Comprehensive link budgets for both VHF and S-band are provided, along with the potential information rates for each option. These are 9.6 kbit/sec for a handheld VHF user terminal with an omni antenna, and 1024 kbit/sec for S-band with a frustum-configured, four-element phased-array antenna. The link margin is 4–5 dB, allowing for interference and variation in distance to the satellite.