A Novel Design Technique for Ultrawideband Shared Aperture Connected Dipole Arrays

This paper presents comprehensive circuit models for the design and analysis of ultrawideband shared aperture antenna arrays. A novel semi-analytical approach is developed by modifying the previous equivalent circuit model to enable the calculation of the electromagnetic (EM) transparency of dipole array unit cells. Based on the EM transmission characteristics of the low-band dipole, an accurate circuit-based method is introduced for calculating the input impedance of a shared aperture antenna. Notably, the only full-wave simulation required is that of the standalone high-band antenna. To demonstrate the effectiveness of the proposed technique, two distinct shared aperture dipole array designs are presented. In both cases, the high-band antennas are implemented using tightly coupled dipole array (TCDA) elements. The first design achieves a 26.2:1 impedance bandwidth with active VSWR < 2.3 and a low-profile height of 0 . 088 lambda(L), where lambda(L) denotes the free-space wavelength at the lowest operating frequency. The second design achieves a 33.3:1 bandwidth with active VSWR < 3 and a profile height of just 0 . 07 lambda(L). The average total efficiencies of the two designs are 0.86 and 0.85, respectively.