Nonreciprocal Phased-Array Antennas

TL;DR

This paper introduces nonreciprocal phased-array antennas that can independently control transmission and reception patterns using time-modulated resonant elements, breaking the usual symmetry and enabling advanced electromagnetic applications.

Contribution

The paper presents a novel design of nonreciprocal phased-array antennas utilizing time-modulated resonant elements for independent pattern control in transmission and reception.

Findings

Achieved over 40 dB isolation in radiation patterns.

Demonstrated low overall loss below 4 dB.

Confirmed effectiveness at microwave frequencies.

Abstract

A phased-array antenna is a device that generates radiation patterns whose shape and direction can be electronically controlled by tailoring the amplitude and phase of the signals that feed each element of the array. These devices provide identical responses in transmission and reception due to the constrains imposed by time-reversal symmetry. Here, we introduce the concept of nonreciprocal phased-array antennas and we demonstrate that they can exhibit drastically different radiation patterns when operated in transmission or in reception. The building block of the array consists of a time-modulated resonant antenna element that provides very efficient frequency conversion between only two frequencies: one associated to waves propagating in free-space and the other related to guided signals. Controlling the tunable nonreciprocal phase response of these elements with the phase of low-frequency modulation signals permits to independently tailor the transmission and reception radiation patterns of the entire array. Measured results at microwaves confirm isolation levels over 40 dB at desired directions in space with an overall loss below 4 dB. We believe that this concept can be extended across the electromagnetic spectrum provided adequate tuning elements are available, with important implications in communication, sensing, and radar systems, as well as in thermal management and energy harvesting.