Unified and Integrated Circuit Antenna in Front End—A Proof of Concept

Abstract

A concept of seamlessly colocated and cointegrated antennas and front-end chain circuits in the form of a unified and integrated design space is proposed, studied, and demonstrated in this paper, which strives to create future joint circuiting-radiating front-end analog functional blocks. To show the proposed concept, the building elements involving dual-function amplifier antenna are highlighted as an example and arranged in a series-connected array, each acting simultaneously as a matching circuit and transmitting antenna. In other words, a single geometrical space serves as both circuits and antennas, meaning a space overlap in which the circuit is an antenna and the antenna is a circuit. This reflects both the harmony and harmonious relationship of the circuit antenna. In this paper, the spacing between two neighboring array elements is utilized to accommodate active devices, such as transistors, in this example. As the first theoretical and experimental demonstration, this paper involves the design of patch antennas, the analysis of mutual coupling, and the placement of amplifying transistors in different operation modes. The modeling procedure for a <inline-formula> <tex-math notation= LaTeX >$1 \\times N$ </tex-math></inline-formula> amplifier-antenna system is presented. The proposed concept is experimentally validated by prototyping a <inline-formula> <tex-math notation= LaTeX >$1 \\times 2$ </tex-math></inline-formula> amplifier-antenna array at 5 GHz with rectangular patches and off-the-shell HJ-FET. An equivalent circuit network is established for the proposed dual function block. Measured results show that the experimental block has −10 dB matching bandwidth of 125 MHz at the steering angle of +30° with an amplifying gain of 11.5 dB. It is also experimentally illustrated that frequency tuning and beam steering can easily be enabled by varying the dc bias. The design of <inline-formula> <tex-math notation= LaTeX >$1 \\times 4$ </tex-math></inline-formula> amplifier-antenna array at 5 GHz is also discussed to generalize the proposed theory and guide the design of higher order amplifier arrays.