Dual-band loop-loaded printed dipole array

A loop-loaded printed dipole (LLPD) array is introduced for a dual-band operation at 3.0/5.5 GHz bands. Loop elements placed on the dipole aperture provide a dual-band operation without deteriorating gain and pattern characteristics. In addition, a new balun-feed configuration with a tapered microstrip transition backed by a triangular ground plane is also introduced to eliminate the inherent unbalanced current excitation of a coaxial feeding element. A corporate-feed structure is also employed for the excitation of the 2 × 2 LLPD array. It is numerically demonstrated that the proposed array offers a minimum 15% impedance bandwidth and a realized gain of at least 10 dB at the designated frequency bands. The full-wave analyses of the LLPD designs are carried out using CST Microwave Studio.