Abstract
Orthogonality in multibeam antennas is revisited. The difference between orthogonal beamforming and zero-forced beamforming is highlighted. The intriguing relation between orthogonality, reciprocity and losses is recapitulated. Different approaches on the design of orthogonal beamforming networks and implementation of zero-forced beamforming strategies are shown with various examples from the antenna-research-oriented literature. The use of orthogonal and zero-forced beamforming is discussed from the communication system perspective with relevant studies from diverse disciplines. Some of the future research challenges and potential benefits are outlined for the next generation satellite and cellular communication applications.
Highlights
Most arrays onboard multiple beam satellites so far, including Iridium, Globalstar, Iridium have generated fixed/switched multiple beam footprints with several users per beam
The aims are: (i) to highlight the differences between orthogonal beams and zero-forced beams, (ii) to briefly explain the relation between the three concepts extensively used in linear microwave circuits; orthogonality, losses and reciprocity, from an antenna perspective, (iii) to review the literature on orthogonal beamforming networks and flexible zero-forced beamforming architectures, (iv) to show the potential use of orthogonal beamforming and zero-forced beamforming in the signal processing domain for communication system studies, and (v) to provide the reader with insights, future research directions and foreseen challenges
Certain reciprocal lattice conditions and that the phase steering vectors of the lossless beamforming network must correspond to the multi-dimensional Discrete Fourier Transform (DFT)
Summary
Most arrays onboard multiple beam satellites so far, including Iridium, Globalstar, Iridium have generated fixed/switched multiple beam footprints with several users per beam. Most commercial space communication systems use fixed or hopped multiple beams with limited co-channel interference control It can be seen in the latest state-of-the-art that phased arrays are being considered for civilian satellite applications as well. The aims are: (i) to highlight the differences between orthogonal beams and zero-forced beams, (ii) to briefly explain the relation between the three concepts extensively used in linear microwave circuits; orthogonality, losses and reciprocity, from an antenna perspective, (iii) to review the literature on orthogonal beamforming networks and flexible zero-forced beamforming architectures, (iv) to show the potential use of orthogonal beamforming and zero-forced beamforming in the signal processing domain for communication system studies, and (v) to provide the reader with insights, future research directions and foreseen challenges. Certain reciprocal lattice conditions and that the phase steering vectors of the lossless beamforming network must correspond to the multi-dimensional Discrete Fourier Transform (DFT)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
