Rapid Prototype Development and Demonstration of a Frequency-Multiplexed Phased-Array Antenna System

Abstract

A phased array is a directive, electronically steered antenna consisting of multiple antenna elements wherein each element’s signal has a unique phase shift applied so that the combined phase-shifted contributions from each element form an antenna beam in the desired direction for both transmission and reception. Phase shifting and beam formation had been performed using analog components outside of the radio transceiver until the advent of digital signal processing introduced digital beamforming. With digital beamforming, the signal from each antenna element is connected directly to an analog to digital converter (ADC) input of a multichannel transceiver. The phase shifting and combining is performed during the digital processing, allowing for fast beam hopping and complex beam pattern generation. However, multiple ADCs can be costly in terms of size, weight, and power (SWaP) and overall complexity, particularly as the number of elements in the phased array increases. This article describes the development, fabrication, and testing of a new type of digital beamforming phased-array antenna system by researchers at the Johns Hopkins University Applied Physics Laboratory (APL). The system frequency-multiplexes the signal from multiple antenna elements onto a single analog line, offering potential solutions for applications where cost and size are of concern. This system can also operate as a coherent multichannel transceiver, offering similar cost and size savings. This project, which progressed from concept to hardware to successful field testing in less than a year, exemplifies the results that APL—leveraging its multidisciplinary teams, world class engineering expertise, and state-of-the-art fabrication facilities—is able to achieve.