Miniature wideband UHF circularly polarized antenna using textured dielectric loading

Use of high permittivity dielectrics in antenna design reduces the operating frequency but also introduces side effects such as lower gain and bandwidth. To provide an optimal compromise between size, gain and bandwidth, the paper presents a miniaturization scheme for a 15 cm (6 inch) square circularly polarized (CP), cavity-backed antenna using textured dielectric loading and a folded metallic strip feed. The proposed design has an operational frequency of 400-600 MHz, implying a linear size of 0.2λ₀ to 0.3λ₀. The challenge for a small size antenna design is to increase bandwidth while retaining a gain of 2-4 dBi. By carefully positioning high permittivity textured dielectrics within the aperture in conjunction with shape design, we show that bandwidth and gain are retained as compared to similar sized antennas in the literature. Our final design shows that the developed miniature UHF antenna is at least half the size of the best available. Concurrently, it delivers a remarkable 23% bandwidth with an equally remarkable gain of ∼4 dBi. Validation/measured data for a prototype design are included.