Broadband Circularly Polarized Microstrip Patch Antenna Using Circular Artificial Ground Structure and Meandering Probe

Abstract

To enhance axial ratio (AR) bandwidth, this research proposes a circularly polarized (CP) single-fed microstrip patch antenna using a circular artificial ground structure (AGS) and meandering probe. To achieve broader AR bandwidth, the circular AGS is populated with rectangular unit cells and partially cut unit cells along the circular contour, while the meandering probe is used to improve the impedance bandwidth. Simulations are performed and results compared with that of conventional rectangular-AGS antenna. The simulation results show that the circular-AGS antenna, given 62 mm circular ground plane, achieves broader impedance (5.12-9.00 GHz and 54%), AR (5.21-8.27 GHz and 45%) and gain bandwidths (3.85-7.00 GHz and 58.06%), in comparison with the rectangular-AGS antenna (4.50-7.45 GHz and 49%; 4.52-7.42 GHz and 21%; and 4.00-6.80 GHz and 51.58% for impedance, AR and gain bandwidths). The circular-AGS antenna is capable of converting linear polarization in the off-axial ratio band into circular polarization. To verify, a circular-AGS antenna prototype is fabricated and experiments undertaken. The experimental impedance, AR and gain bandwidths of the circular-AGS antenna are 47.82% (5.17-8.42 GHz), 43.81% (5.24-8.17 GHz) and 60.74% (3.75-7.00 GHz). The proposed circular-AGS antenna can achieve broader AR bandwidth and is thus ideal for broadband CP applications. The novelty of this research lies in the use of circular AGS to effectively enhance AR bandwidth, as opposed to rectangular AGS which is conventionally used in CP polarizers. INDEX TERMS Artificial ground structure (AGS), artificial magnetic conductor, broadband antenna, circular polarization, microstrip patch antenna.

Thin Circularly Polarized Slot Array Antenna for High-Band UWB Applications

“…The maximum gain of the array antenna exhibited an increase of 3.38 dBic compared with that of the antenna element. Next, in Table 1, the proposed antenna was compared with other reported antenna [19][20][21][22][23][24]. The proposed technique based on the slot antenna structure has a distinct ad vantage over other state-of-the-art designs in the context of antenna thickness.…”

“…However, when compared with the simulation results, a gain decrease of approximately 1 dB was observed in some frequency bands and this was assumed to be due to the measurement environment and errors during board construction. Next, in Table 1, the proposed antenna was compared with other reported antennas [19][20][21][22][23][24]. The proposed technique based on the slot antenna structure has a distinct advantage over other state-of-the-art designs in the context of antenna thickness.…”

Broadband Circularly Polarized Microstrip Patch Antenna With Diamond-Shaped Artificial Ground Structure

“…However, microstrip patch antennas have relatively narrow impedance and 3-dB axial ratio (AR) bandwidths. Artificial ground structures (AGSs), which act as an artificial magnetic conductor and a polarizer, have been proposed for achieving broadband circular polarization (CP) and impedance for patch antennas [3] - [17]. In conventional AGSs, rectangular unit cells are arrayed periodically so that their sides are parallel to the sides of a grounded rectangular substrate.…”