  Impedance-matching networks affect power transfer from the radio frequency
(RF) chains to the antennas. Their design impacts the signal to noise ratio
(SNR) and the achievable rate. In this paper, we maximize the
information-theoretic achievable rate of a multiple-input-single-output (MISO)
system with wideband matching constraints. Using a multiport circuit theory
approach with frequency-selective scattering parameters, we propose a general
framework for optimizing the MISO achievable rate that incorporates Bode-Fano
wideband matching theory. We express the solution to the achievable rate
optimization problem in terms of the optimized transmission coefficient and the
Lagrangian parameters corresponding to the Bode-Fano inequality constraints. We
apply this framework to a single electric Chu's antenna and an array of two
electric Chu's antennas. We compare the optimized achievable rate obtained
numerically with other benchmarks like the ideal achievable rate computed by
disregarding matching constraints and the achievable rate obtained by using
sub-optimal matching strategies like conjugate matching and frequency-flat
transmission. We also propose a practical methodology to approximate the
achievable rate bound by using the optimal transmission coefficient to derive a
physically realizable matching network through the ADS software.
