Low-Scattering Dipole Antenna Using Mushroom-Shaped Structure for Applications in Dual-Band Shared-Aperture Array

A low-scattering dipole antenna by loading mushroom-shaped electromagnetic structures is proposed and employed to design an aperture-shared antenna array with low blockage effect. The arm of the proposed dipole element consists of a square ring and a short branch, and the mushroom structure is loaded on the arm to realize low scattering characteristics. The low scattering low band (LB) element is used for a dual-band shared-aperture array; the results indicate the pattern distortion of the high band (HB) array caused by the LB element can be greatly reduced accordingly. Compared with HB antenna alone, the simulated maximum gain decrease is 1.55 dB and the maximum beamwidth deviation is 27.4° after adding the reference LB dipole without loading the mushroom-shaped structure. Meanwhile the two values are reduced to 0.55 dB and 6.4°, respectively, after the mushroom-shaped structure is loaded. For demonstration, an aperture-shared antenna array operating in the LB of 0.698–0.96 GHz and the HB of 3.4–3.8 GHz is designed and fabricated. The measured results show that the
S
-parameters and the pattern of the HB subarray with the proposed LB dipole change slightly, indicating that the proposed LB dipole can effectively suppress the scattering on the HB antenna. The results indicate the proposed design is suitable for multiband aperture-shared antennas in modern communication systems.