Axial Ratio and Gain Enhancement of a Circular-Ring Slot Antenna Using a Pair of Asymmetrical Rectangular Slots and a Parasitic Patch for a Radio Beacon on a Nanosatellite

Abstract

Radio beacons enable measurements of ionospheric radio scintillations and total electron content (TEC). These beacons transmit unmodulated, phase-coherent waves in S-band frequencies. Many satellite applications require circularly polarized (CP) wideband antennas. Their compact size, lightweight, and simple fabrication method make CP antennas suitable for small satellite systems. The slot antenna has wideband impedance, but the 3 dB axial ratio bandwidth (ARBW) is narrower compared to the impedance bandwidth (IBW). In this paper, a circularly polarized circular-slotted antenna (CSA) is proposed to enhance the ARBW and the antenna gain. A pair of asymmetrical rectangular slots, a simple 50 Ω feedline and a parasitic patch were introduced to a CSA to enhance the 3 dB ARBW and the antenna gain. Rectangular slots were inserted on the diagonal axis of the CSA, the feedline was shifted to the left side of the x-axis, and a parasitic patch was attached to the circular slot. The lengths of the rectangular slots correspond to the resonant frequency, and the parasitic patch width corresponds to the higher frequency of the 3 dB ARBW. The asymmetrical rectangular slots, the shifted feedline, and the parasitic patch successfully improved the measured 3 dB ARBW of the antenna by 787.5 MHz or 35.79%. The measured gain of a CSA with left-hand circular polarization (LHCP) was also improved by shifting the feedline and the rectangular slot, achieving a peak gain of 5 dBic.

Inverted L-Shaped CP Patch Antenna with Corner-Truncated Partial Ground Plane Diagonally Adjoined with Square Branch for L-Band Applications

“…Given the target L-band frequency (1-2 GHz), the ARBW of the proposed antenna scheme (77.87%) was significantly wider than that of [13,15] (19.86% and 36.87%, respectively). In comparison with [16,[22][23][24], for C-and S-band applications (30.8-72.9%), the proposed antenna scheme could achieve a wider ARBW (77.87%). Table 4.…”

Recent Trends in Compact Planar Antennas at 5G Sub-6 GHz and mmWave Frequency Bands for Automotive Wireless Applications: A Review

“…Wide-beam CP radiation is a feature of the projected antenna that makes it desirable for RF energy harvesting applications. In another research paper, a circularly slotted antenna is presented in [29], and the design is shown in Figure 2(c). This research aimed to develop a design for enhancing a circularly slotted antenna's CP performance in order to achieve wide 3-dB axial ratio bandwidth and a higher gain at 2.4 GHz.…”

Fully Integrated High Gain S-Band Triangular Slot Antenna for CubeSat Communications

“…A qualitative comparison between the proposed equilateral CPW-fed slot antenna and six S-band antenna designs with metasurface [20][21][22][23][24][25][26][27][28][29][30][31] is now provided; refer to Figure 25. We analyze, compare, and evaluate the suitability of all these antenna designs for 3U CubeSats using the following criteria: small physical size at S-band, wide impedance and Axial Ratio bandwidth, low reflection coefficient (<−10 dB), orientability, and high gain at S-band.…”