Miniaturized Differentially-Fed Circularly Polarized Antenna Based on SRR

A miniaturized differentially fed circularly polarized (CP) patch antenna based on split-ring resonator (SRR) for WIFI applications is proposed. Capacitive gaps and metallic screws are used to construct the SRR structure. The CP antenna with a compact size is implemented by the two crossed dual-capacitor SRRs. Composite right/left-handed transmission line (CRLH-TL) loaded differential Wilkinson power divider is proposed to realize an integrated design and a relatively pure CP radiation. Owing to the novel SRR structure, a compact size of 0.24
$\boldsymbol{\lambda_{0}\times 0.24\lambda_{0}\times 0.04\lambda_{0}(}$
where
$\boldsymbol{\lambda_{0}}$
is the free space wavelength at 2.4 GHz) is achieved. The measured -10 dB impedance and 3 dB AR bandwidth are 16.25% and 3.3%, respectively. The measured peak gain and efficiency are 5.5 dBic and 81.3%, respectively.