Near-Space Microwave Radar Remote Sensing: Potentials and Challenge Analysis

Abstract

Near-space, defined as the region between 20 km and 100 km, offers many new capabilities that are not accessible to low earth orbit (LEO) satellites and airplanes, because it is above storm and not constrained by either the orbital mechanics of satellites or the high fuel consumption of airplanes. By placing radar transmitter/receiver in near-space platforms, many functions that are currently performed with satellites or airplanes could be performed in a cheaper way. Inspired by these advantages, this paper introduces several near-space vehicle-based radar configurations, such as near-space passive bistatic radar and high-resolution wide-swath (HRWS) synthetic aperture radar (SAR). Their potential applications, technical challenges and possible solutions are investigated. It is shown that near-space is a satisfactory solution to some specific remote sensing applications. Firstly, near-space passive bistatic radar using opportunistic illuminators offers a solution to persistent regional remote sensing, which is particularly interest for protecting homeland security or monitoring regional environment. Secondly, near-space provides an optimal solution to relative HRWS SAR imaging. Moreover, as motion compensation is a common technical challenge for the described radars, an active transponder-based motion compensation is also described.

Azimuth-Variant Signal Processing in High-Altitude Platform Passive SAR with Spaceborne/Airborne Transmitter

“…It appears that HAP or near-space vehicle can provide an optimal platform for passive BiSAR due to the following reasons [9,10,21]: HAP includes free-floater and maneuvering vehicle, but this paper considers only the free-floater. Free-floater has extremely small radar cross section (RCS), making it relatively invulnerable to most traditional track and location methods.…”

“…By placing a radar transmitter or receiver inside a HAP, many functions that are currently performed by satellites or airplanes could be performed in a more efficient way [10]. In [11], we investigated the application of HAP passive radar for regional remote sensing.…”

Performance Analysis of Bistatic Interferometer Based on Spaceborne Sar

“…Assuming that the SNR of two images is same, and then the de-correlation effect caused by SNR can be rewritten as [17] γ SNR = 1 1 + SNR −1 (16) According to the radar equation of the bistatic SAR [26], the SNR of BIBASS can be given as:…”

“…As a passive single-pass interferometric system, BIBASS benefits from flexibility, low-cost, wide-swath, low temporal decorrelation and reliability [16]. This enables that BIBASS will be widely applied in the future missions.…”

Fa-Scansar: Full Aperture Scanning Pulse by Pulse for the Nearspace Slow-Moving Platform Borne Sar

“…And the nearspace SAR has been becoming a revolutionizing remote sensing mission [15]. Recently most researches [15][16][17] have concentrated on the ultrasonic aircrafts borne SAR because the SAR system parameters of them are similar to those of conventional airborne SAR, and the traditional SAR techniques can be extended to the ultrasonic aircrafts. In contrast to the ultrasonic aircrafts, for the slowmoving platform borne SAR, it is too hard to compensate the motion errors because of the long aperture time caused by the slow velocity.…”