Efficient, High Directivity, Large Front-to-Back-Ratio, Electrically Small, Near-Field-Resonant-Parasitic Antenna

Enhancements of the directivity and front-to-back ratio (FTBR) of a metamaterial-inspired electrically small, linearly polarized, coaxially-fed Egyptian axe dipole antenna are considered. They are accomplished with a particular augmentation of the original near-field-resonant-parasitic (NFRP) antenna with an additional NFRP element, a small disc conductor modified with two meanderline-shaped slots. The entire system is evaluated numerically with two independent computational electromagnetics simulators. The optimized results demonstrate an electrically small antenna (i.e., ka < 1.0) with a reasonably low profile (i.e., height similar to lambda/10) that improves the directivity from 1.77 to 6.32 dB, increases the FTBR from 0 to > 20 dB, and maintains large half-power beamwidths, while having a radiation efficiency over 80% with nearly complete matching to a 50 Omega source.