3D‐printed circularly polarized concave patch with enhanced bandwidth and radiation pattern

In this article, a novel design of a probe‐fed circularly polarized (CP) patch antenna on a 3D‐printed concave‐shaped substrate is proposed. The radiating patch conforms to the concavity of the substrate surface, and the circular polarization is achieved by two pairs of asymmetric slot perturbation. The varying substrate thickness due to the concavity across the cross‐section enhances the antenna's bandwidth by 1.99% compared to traditional flat substrates. The spherically curved surface focuses the antenna's radiation by narrowing its half‐power beam‐width (HPBW). The gain and axial ratio of the antenna are also less susceptible to the effects of having a large ground plane. The results are verified by comparing the measured performance of the proposed antenna with that of a conventional corner truncated CP patch on a 3D‐printed flat substrate. The proposed antenna is designed for sub‐GHz industrial, scientific, and medical radio (ISM) band (865‐868 MHz) and has 7 dBiC gain and near 0 dB axial ratio with 65° and 61° HPBW in elevation, and azimuth planes, respectively.