LAUSR

Parasitic antenna arrays (PAAs) with a single radio frequency (RF) chain have been used to enable new trends and paradigms for multi-antenna transmission. Significant reduction in hardware complexity, size, and cost can be obtained with single-RF PAAs, as only the active element (AE) is directly connected to the voltage through an RF connection. The performance of a PAA can be further enhanced for multi-antenna transmission by increasing its number of AEs, thus creating a multi-active/multi-passive (MAMP) antenna array. The problem of finding the desired tunable loads for parasitic elements involves ensuring that the array will radiate. In this letter, we provide (for the first time, to our best knowledge), closed-form expressions for the constraints that the parasitic load values of MAMP antenna arrays need to satisfy for the array to radiate.