Antenna Link Transfer Function Factorization Applied to Optimized Channel Design

Abstract

A channel broadband factored model is developed and numerically verified with a method of moment (MoM) technique for design of optimized UWB links with real, dispersive antennas. In this study, two-antenna link transfer functions are decomposed into port-load and full-wave dependent components based on general linearity and reciprocity in electromagnetics. Specifically, the port-related components account for antenna termination to the transmitter generator and front-end receiver circuits as antenna loads. In turn, the wave portion, which is associated with link transmission impedance, involves all geometrical factors like antenna shapes and their positioning/pointing in space that account collectively for radiation, propagation and reception. As a result, any link of fixed geometry can be full-wave numerically simulated just once for a suitable set of reference generator/load impedances. Then, all variations in link performance caused by variable port terminations are easily predicted by manipulating the full-wave data obtained for the case of reference antenna port loads. This approach provides some useful physical insights and an optimized co-design procedure for transmitter and receiver impedances to meet several significant performance-related design objectives, such as: i) maximized link energy transmission efficiency; ii) maximum amplitude of received signals; iii) minimized time confinement for signal energy at receiver loads; iv) flatness of magnitude of link transfer functions; and v) minimized group delay deviation. The major results are numerically illustrated for a number of useful far-field line-of-sight link cases with flat and solid dipole antennas operating in up to 3:1 bands and ideally aligned in terms of their gain and polarization matching. Numerical results are given in a normalized form and scalable to any band of interest