Vertical Polarized 1 × 3 Series-Fed Linear Array With Gain and Front-to-Back Ratio Enhancement for Airborne Sar-X Applications

Abstract

In this paper, a gain and front-to-back ratio (FTBR) enhanced vertically polarized 1 × 3 series-fed linear array for Airborne Synthetic Aperture Radar-X-band applications has been presented. The proposed antenna prototype is designed at 9.65 GHz (X-band). The design consists of a square radiating patch, substrate, quarter wave transformer, 50 Ω matched transformer, and series feed line (SFL). The simulated antenna prototype is fabricated and successfully measured. The final antenna prototype has a dimension 3.256 × 2.035 × 0.0645λ 3 g (Guided wavelength) at 9.65 GHz. The results indicate that the proposed antenna prototype yields an impedance bandwidth > 140 MHz (from 9.591 to 9.712 GHz) defined by S11 < −10 dB. The low profile/cost antenna prototype has a fully directional radiation pattern with measured gain up to 12.2 dBi and estimated radiation efficiency of 89%, respectively. A brass plate with 0.8 mm thickness has been fabricated to attach to the antenna ground plane for improving FTBR of more than 30 dB. All these features make the proposed antenna array have good potential applications in X-band system, especially in 9.65 GHz Airborne SAR systems. The aperture of the antenna is 80 mm × 50 mm, which equals 31 wavelengths at 9.65 GHz.

A Single-Layer S/X- Band Shared Aperture Antenna with MIMO Characteristics at X-Band for Airborne Synthetic Aperture Radar Applications

“…Still, all of them achieve low isolation compared to the proposed antenna in which isolation is performed at more than 38 dB. While comparing the bandwidth in [4], the S-Band is relatively low compared to our proposed antenna, which achieves a frequency of 0.12 GHz when compared to X-Band frequency, i.e., 0.27 GHz, which is superior bandwidth compared to the articles [4,10,12,14,15]. Regarding the application concern, we need to take the antenna size.…”

“…Regarding the application concern, we need to take the antenna size. Size complexity is present in terms of length, breadth, and thickness when comparing the dimensions of the proposed antenna with the antennas of articles [2][3][4][5][6][7][8][10][11][12][13][14][15][16]. Our antenna is small in size and produces better compatibility.…”

“…To design the radar application and for better results, we used to design the antenna using Chebyshev amplitude distribution (CAD) and uniform amplitude distribution (UAD) [13]. Gain and front-to-back ratio are improved in series-fed linear array antenna, which is useful in Radar-X-band applications [14]. Using the Chebyshev technique with a width-controlled patch antenna to incorporate both Xband and K-band to achieve better results, we can use linear or circular polarization within a single-layer [15].…”