Analysis and Impact of Port Impedances on Two-Port Networks and Its Application in Active Array Antenna Developments.

In this work, we present a comprehensive analysis of port impedance effects on a signal coupled across two-port networks, derive an equation to evaluate the impedances for a specified coupling, and demonstrate two beam-shaping active array antenna prototypes to validate the theory. In this context, the generalized S-parameters are theoretically studied and verified through an example. Subsequently, a closed-form equation is derived to accurately evaluate the port impedances that enable the achievement of a desired magnitude and phase of the signal coupling across the two-port network. The meaningfulness of all the potential results and the additional capabilities of derived equations are then discussed. With this understanding, a general modeling procedure is formulated to achieve the simultaneous amplification and phase shifting only through the active devices, without resorting to any additional passive circuitry. As a proof of concept, two 1 × 5 active array antenna prototypes are developed and fabricated at 5 GHz: one for broadside radiation with a sidelobe level of less than −20 dB requirement, and the other for flat-top radiation beam between −10° and 30°. They are integrated with a 1 × 5 Wilkinson power divider that is designed for radiation pattern measurements, and the corresponding results agree reasonably well with the simulated counterparts and theory, thereby proving the developed concept. Such solutions demonstrate the inherent advantages of being low-loss, compact, and efficient, which are essential for the next generation of wireless systems. [ABSTRACT FROM AUTHOR]