Dual-Band Flexible Endfire Filtering Antenna With Conformal Capability for Emergency Communication Applications

In this letter, a single-layer dual-band flexible conformal filtering endfire antenna is presented. The proposed antenna is based on two co-designed folded dipoles (FDs) working at two frequencies, where the lower-frequency FD acts as a reflector for the higher-frequency one. Then, by devising an additional reflector for lower-frequency FD, dual-band endfire radiation is realized. Parasitic strips are deliberately introduced around the FDs to generate electric coupling and magnetic coupling in the two operating bands, resulting in significant filtering performance with four radiation nulls. With flexible structure and single-layer configuration, the antenna design exhibits flexible conformability with cylindrical surfaces of diverse diameters, thereby enabling seamless integration into scalable emergency communication systems. To verify our design concept, an antenna prototype is fabricated and measured. The measured working frequency ranges from 1.37 to 1.45 GHz and 1.89 to 2.07 GHz. Out-of-band radiation suppression more than 11 dB is achieved under different bending radii. The proposed design offers several advantages including dual-band endfire filtering radiation, flexible conformability and low-profile.