An Energy-Selective Beamforming Approach for HPM Protection in Array Antennas

This article introduces an energy selective beamforming array (ESBA) that adaptively adjusts its array factor in the defense mode for safeguarding sensitive front-end circuits from high-power microwave threats. Novel energy selective phase shifters (ESPSs) are integrated with the ESBA to impart chaotic phases signals exceeding the threshold level, by which the ESBA enters a defocused state. Operational mechanism of the ESPS is explained through equivalent circuit and resonance theory, and a comprehensive design methodology is provided for ESBA. Notably, the defense level of the proposed ESBA scales with the array size, which shows a great advantage over other protection methods. Furthermore, the ESBA is compatible with other energy-selective protection methods and electronic beam-scanning technologies. To validate this concept, a microstrip-patch-based prototype is fabricated and measured. Theoretical, numerical, and experimental results demonstrate good agreements. The prototype operates in the frequency range of 2.3–2.4 GHz, providing a maximum protection level of approximately 52 dB in the defense mode. The insertion loss introduced by the ESPS is maintained within 1 dB. With its compact form factor and low manufacturing cost, the ESBA technology is suitable for passive and active phased arrays.