No abstract

This article proposes an ultra‐wideband coplanar strips (CPS) rectangular spiral antenna that is fed by coplanar waveguide (CPW). The CPS is formed by gradually reducing the width of the CPW ground planes without the need of a balun. The antenna operates in the frequency band (3.5‐10.6 GHz) and has miniaturized size of 50 × 40 × 0.508 mm on a Rogers RO4003C substrate. The CPS spiral is terminated with a 100 Ω chip resistor for matching. A parametric study was performed to choose the CPS spiral dimensions. A good agreement is found between simulations and measurements in the radiation pattern and the return loss which was found to be better than 10 dB over the band. The measured peak gain ranges between 1 and 4.7 dBi.

In this study, a new design of a planar ultra‐wideband (UWB) monopole antenna with a rose‐curve contour shape is proposed. The rose‐curve circumference of the monopole is expressed in polar coordinates as: r=r0+acos)(nθ. This function enables a flexible and easy to control layout, which directly affects the antenna's response. The arguments of the function are specified based on a simple deterministic design rule and the outputs of a parametric study. The antenna covers the 3.1–11 GHz band and has an ultra‐miniaturised size of 864 mm3 when realised on a RT/Duroid 6010LM substrate of 0.635 mm thickness. To add dual‐notch characteristics to the proposed antenna, a complementary dual‐band split ring resonator inclusion is etched on the antenna's patch near the feeding line. The inclusion is designed to operate at the two Wi‐Fi and ISM frequency bands, 3.5 and 5.8 GHz, respectively. These centre band frequencies are determined using a new hybrid method that utilises the resonant and non‐resonant design approaches of metamaterial structures. Simulated and measured return loss values, radiation patterns and gain values for the proposed antennas (with and without notching) are in very good agreements, and demonstrate satisfactory performance.