Radiation enhancement of compact folded slot antenna using capacitor-loaded CPW

In spite of the compact size and uniplanar structure, coplanar waveguide (CPW) fed folded slot antennas have two major disadvantages, namely higher cross-polarization levels and lower radiation efficiency. In this work, a short section of capacitor-loaded (CL) CPW is utilized to feed the folded slot antenna so that a reduced cross-polarized radiation and higher efficiency can be obtained. The design procedures for the proposed antenna are presented, and a 5.9-GHz prototype antenna is fabricated and tested for verification. The antenna has not only a compact area of 0.13λ₀ × 0.15λ₀ but an improved efficiency of 75% and lower cross-polarization levels (<; 15 dB).