An Energy Selective Antenna Based on the Folded Dipole Structure and PIN Diodes

An energy selective antenna (ESA) concept is proposed by controlling the surface current distribution with PIN diodes. Realized gain of the proposed antenna depends on the intensity of the incident wave through the turn-on state of PIN diodes. In the high-intensity radiated field (HIRF) environment, the proposed antenna forms a new surface current loop and adaptively reduces the effective aperture area. Operating mechanism of the ESA is explained through the circuit theory. It is found that the loading position of PIN diodes is the key parameter that determines both the protection capability and antenna performance. Meanwhile, this topology fits well with some variations of the PIN diode parameters. To demonstrate this new topology, a conceptional design of energy selective folded dipole antenna is presented and fabricated. The theoretical, numerical, and experimental results agree well for the prototype antenna. The proposed antenna provides ∼20 dB protection level in the defense mode, while the PIN diodes reduce the antenna gain by only 0.3 dB in the normal mode. Since the ESA does not increase the antenna size or fabrication cost, it provides a new alternative for protecting RF front-end in the HIRF environment.