ArcSAR: Theory, Simulations, and Experimental Verification

Abstract

ArcSAR is a ground-based synthetic aperture radar (GBSAR) that has recently been receiving increasing interest in the scientific literature. While the conventional GBSAR exploits the movement of an antenna along a linear rail to synthesize a large aperture, an ArcSAR exploits the spatial diversity of the data acquired by an antenna fixed to a rotating arm. The great advantage of ArcSAR is its capability to synthesize images at 360°with a constant resolution in azimuth. In this paper, the authors propose and test a new focusing algorithm that does not require to operate in the far field and neither with narrow beam antennas; moreover, it is flexible enough to focus on any plane (not necessarily on the rotation plane) as well as in the whole 3-D space. Furthermore, the authors demonstrate theoretically and experimentally that ArcSAR images can be affected by a "defocusing effect" of the targets far from the rotation plane, which has to be taken into consideration when designing such radars.

Focusing Arc-Array Bistatic Synthetic Aperture Radar Data Based on Keystone Transform

“…Different from other SAR modes, the azimuth resolution along arc antenna array direction in AA-BiSAR, also called azimuth angular resolution or array angular resolution (unit is degree) [14][15][16][17][18][19][20][21], is achieved by an arc synthetic aperture formed with several antenna elements and echo signal coherent integration. As shown in Figure 1b, due to the structure of the receive arc-array antenna of AA-BiSAR, the instantaneous azimuth frequency f θ is always perpendicular to the radius of the arc-array antenna.…”

“…The traditional linear array SAR (LA-SAR) [8][9][10][11] can only observe the front area of the antenna array unit from a single angle of view. Compared with LA-SAR, arc-array SAR (AA-SAR) [12][13][14][15][16][17][18][19][20][21] is a novel array microwave imaging mode with full azimuth observation, which breaks through the limitation of the single observation angle of conventional LA-SAR. Furthermore, AA-SAR can realize quickly high-resolution imaging in area around the imaging platform.…”

Cross-Pol Transponder with Frequency Shifter for Bistatic Ground-Based Synthetic Aperture Radar

“…where Iij (foc) is the radar image focused using the algorithm in [10]; P0 = 19 dBm is the transmitted power; Tmeas is the integration time that is given by the time of a single continuous wave (CW) measurement multiplied by the number of frequency (Nf = 801) and the number of positions (Np = Figure 12. Picture of the transponder in the field.…”

Bistatic GBSAR for detecting target elevation

“…A vector network analyser (VNA) HP8720D operated as a transceiver providing a continuous wave stepped frequency signal (CWSF) in X-band with central frequency fc =10 GHz and bandwidth B = 160 MHz. The bistatic radar images were focussed with a back projection algorithm that takes into account of the phase history of any path radar-target-transponder-radar [5], [6].…”