Simple and Electrically Small EZR-MZR Resonator With Quasi-Isotropic Pattern

A new zeroth-order resonator that composites epsilon-zero resonance and mu-zero resonance characteristics (called EZR-MZR resonator) can be used to design quasiisotropic antenna. Compared to the presented quasi-isotropic antenna, the EZR-MZR resonator has the advantages of simple structure for high efficiency design and electrically small size. The EZR-MZR resonator includes a patch, a ground plane, and a shorting pin. The single frequency EZR-MZR resonator with rectangular patch has a volume of 0.13 λ
_r
× 0.20 λ
_r
× 0.03 λ
_r
(where λ
_r
is the free space wavelength of the resonant frequency f
_r
= 1.500 GHz). While the dual frequencies antenna (f
_r1
= 1.038 GHz and f
_r2
= 1.443 GHz) with two curved EZR-MZR resonator has a volume of 0.078 λ
_r1
× 0.214 λ
_r1
× 0.024 λ
_r1
(where λ
_r1
is the free space wavelength of the resonant frequency f
_r1
). The field distributions, patterns of different polarizations, Z/S-parameters and parametric studies were used to reveal the operational mechanism of the EZR-MZR resonator antenna. The resonant frequency of the EZR-MZR resonator can be easily tuned by adjusting the size parameters of the resonator, thus, the EZR-MZR resonator with quasi-isotropic pattern is a good candidate to design antenna that accommodates with different RFID frequency.