Electrically small, low‐profile, full‐duplex Huygens dipole filtenna

Abstract

AbstractAn electrically small, full‐duplex Huygens dipole filtenna (HDF) is realized as a dense array of two HDF elements consisting of Egyptian axe dipole and capacitively‐loaded loop near‐field resonant parasitic (NFRP) elements. The dual‐band HDF elements operate at two very nearby frequency bands and are physically separated by only 0.12 λLB. Benefitting from the HDF element's good out‐of‐band rejection performance characteristics, high isolation levels between the lower‐band (LB) and higher‐band (HB) ports are obtained without any decoupling structure. The measured results, in good agreement with their simulated values, demonstrate that the entire system is electrically small (ka = 0.975) and low‐profile (0.041 λLB). The measured isolation levels at its LB (HB) port is, respectively, over 33.9 (29.2) dB. When the LB (HB) port is excited, its fractional bandwidth, broadside realized gain, front‐to‐back ratio, and overall efficiency values are, respectively, 0.86% (0.77%), 2.1 (2.31) dBi, 8.1 (9.6 ) dB, and 62.1% (62.8%).