For a satellite communications system with simultaneous transmit-receive operation, the center frequencies of receiving and transmitting should be different with orthogonal polarization values. Among the operating frequencies of mobile antennas, Ku-band is being viewed increasingly as its advantages of low cost and wide bandwidth in broadcasting services and bidirectional links which can compete with terrestrial networks.
Providing high data rate satellite communications is of important significance to deliver mission-critical data, voice, and video, for secure and real-time information flow. Far more attractive are hybrid mechanically/electronically steerable solutions, which can be low profile and simultaneously possess fast and accurate pointing capabilities. Combining mechanical steering technology in another dimension, the mobile antenna system is capable of providing near-hemispherical coverage. But the emerging technology of beamforming network, like Rotman lens, provides a solution to implement a one-dimension electronically steerable antenna instead of costly phase shifters. These properties of the previous two types are limitations to commercial exploitation in the automotive, maritime, and airborne applications in the civil field. With naturally low profile, the primary barrier for phased array antennas to gain a larger share of the market is the expensive cost. The main disadvantages of mechanical steering systems are that the resulting user terminals are not low profile, heavy and/or bulky, subject to G-forces, and maintenance intensive. The third type merges the technologies of mechanical steering and electronic steering together for planar antennas. The second type uses RF topologies like the classical phased array approach or Digital Beam Forming (DBF) which are completely electronically steerable. The first type utilizes fully mechanical steering system like a traditional reflector array or a multibeam lens antenna.
The known mobile antenna systems can be generally divided into three types by scanning styles. The ever increasing need for ubiquitous satellite communication (SatCom) services on the move in land, maritime, and aeronautical environments pushes the development of mobile antenna systems.
This type of multibeam orthogonal linearly polarized planar antenna is a good candidate for satellite communication (SatCom). A microstrip Rotman lens is employed as the beamforming network with 7 input ports, which can generate a corresponding number of beams to cover −30°–30° with 5 dB beamwidth along one dimension. By using patches with different coupling methods as elements, both perpendicular polarization in 12.25–12.75 GHz band and horizontal polarization in 14.0–14.5 GHz band are realized in a shared antenna aperture. The design and simulation of a 10 × 8 multibeam dual-band orthogonal linearly polarized antenna array operating at Ku-band are presented for transmit-receive applications.