Data from interferometric synthetic aperture radar (INSAR) can provide three-dimensional information by using the phase as an additional information source derived from the complex radar data. In this paper, the issues, techniques and applications of SAR interferometry are reviewed. After a brief historical review, the geometric implementations of SAR interferometry are described. The general processing techniques are summarized and an introduction to various phase unwrapping techniques is given. Besides the differential use of SAR interferometry, the review focuses on parameters such as baseline, decorrelation and motion compensation which have a limiting influence on the quality of the data. After evaluating the various existing and potential applications using SAR interferometric techniques such as topographic mapping, digital elevation modelling, slope measurement, change detection, classification, ocean currents, polar research, seismic events and volcanic hazards, the paper concludes with s...

SAR interferometry : issues, techniques, applications

Recent years have seen a surging interest in several novel tools pertaining to SAR, such as multichannel high-resolution and wide-swath (HRWS) SAR, multibaseline interferometric SAR (InSAR), multisubband SAR, polarimetric SAR (PolSAR), and polarimetric SAR interferometry (PolInSAR). We believe that these new approaches to SAR have valuable scientific applications. Here, we present a new experimental airborne SAR system named “N-SAR” (SAR of the Nanjing Research Institute of Electronic Technology) that can fulfill new requirements and is scalable to allow rapid development of modern SARs. As a dual-antenna airborne SAR system, the N-SAR system will be used to test new technologies and signal processing algorithms such as PolSAR and PolInSAR, multibaseline SAR interferometry, multichannel multichannel HRWS SAR/InSAR, and SAR ground moving target indicator. It will play a key role in evaluating the performance of current engineering-oriented SAR systems by using several new operational modes for scientific purposes. In this paper, we provide a conceptual description of the general system design features, instrument design, and capabilities of the N-SAR system. To meet the requirements of different experiments, a novel operational mode, named the alternating bistatic multipolarized mode based on the N-SAR system, is presented. A series of flight tests that started in April 2017 and will be carried out over the next few years are shown. Several preliminary experimental results pertaining to the calibration of PolSAR, multichannel SAR imaging, and interferometry are presented in this paper as an early validation of the capabilities of the N-SAR system.

N-SAR: A New Multichannel Multimode Polarimetric Airborne SAR

This paper presents a polylactid-acid (PLA) based 3D printed circularly polarized 2 × 2 X-band horn array antenna for circularly polarized synthetic aperture radar (CP-SAR) sensor. The use of CP horn array antenna is to overcome some issues related with mismatch orientation and ionospheric effect of linear polarization sensor. The proposed array antenna which is intended to operate at X-band frequency is realized using PLA material through 3D printing technique and fed by series sequential feeding network implemented on a 1.6mm thick NPC-F220A dielectric substrate. From the result, it shows that the proposed CP horn array antenna has 3dB axial ratio bandwidth more than 400MHz in X-band frequency range.

PLA-based 3D printed circularly polarized X-band horn array antenna for CP-SAR sensor

The present invention is a system and method for radar detection of moving targets. The radar system of the present invention has only a single transmit phase center and a single receive phase center. The method of the present invention includes radiating a set of pulses to illuminate a desired scene. The pulses are reflected off of a target and a set of return signals are received. The pulse returns are then digitized, resulting in a set of data returns. Motion compensation is then performed on the entire set of data returns. A plurality of blocks of the motion compensated data are selected that are highly overlapping in time. A plurality of images is then generated from the plurality of blocks of motion compensated data. A consecutive set of the plurality of images is then selected. Lastly, moving objects represented within the consecutive set of images are identified.

System and method for moving target detection

A method of analyzing the radar cross section of a target vehicle determines the contributions to total radar cross section of various vehicle design details. The method includes obtaining ISAR images of the vehicle with a radar at a known position relative to the vehicle. A visible three-dimensional set of images of the vehicle is created. The visible images have the same point of view as the ISAR images. Each visible image is matched by one or more corresponding ISAR images in terms of distance from the target and angular position of the target relative to the vehicle's axis of rotation. The corresponding ISAR images are used to paint the visible images so as to produce one or more rendered composite images of the vehicle. A relation is then found between chosen vehicle details and bright zones in the composite image.

Isar method to analyze radar cross sections

A synthetic aperture radar apparatus which analyzes Doppler frequency displacements arising from a range direction motion component of a target and motion components of a flying body to produce a motion target image wherein only azimuth direction motion components of the target are converted into Doppler components. An SAR apparatus wherein SAR reproduction processing is performed based on target information obtained from a reflected wave received from a target and flying information of a flying body includes a recording and reproduction unit for recording the target information and reproducing the data in a designated range, and a moving target processor for analyzing Doppler frequency displacements arising from a range direction motion component of the target and motion components of the flying body from the reproduced data and producing a moving target image wherein only azimuth direction motion components of the target are converted into Doppler components.

Synthetic aperture radar and target image production method

This paper reports the development of a new small airborne SAR, which was developed based on the technology of Pi-SAR2 owned by NICT (The National Institute of Information and Communications Technology). The object is to make it more mobile and more usable for proper disaster monitoring use. The summary of the program was reported in IGARSS 2013 and 2014[2][3][4] and this paper shows the final result.

A new small airborne SAR based on Pi-SAR2

The authors describe the Japanese "NEC-SAR" remote sensing system outline, and data processing, and the summary of evaluation of interferometric images. This terrain imaging radar system is installed in a Cessna 208 aircraft and is capable of producing topographic images.

https://ieeexplore.ieee.org/iel3/3772/11018/00516755.pdf

The NEC interferometric SAR system "NEC-SAR"

This paper shows the development status of a new small airborne SAR based on Pi-SAR2. We had designed its advanced small type high resolution full polarimetric airborne SAR with the real-time processor. Its flight test will be planned in this fiscal year.

Development status of a new small airborne SAR based on Pi-SAR2

Repeat-pass interferometric SAR (INSAR) is considered an excellent tool to detect very slight Earth crustal movement caused by an earthquake, a volcano activity, and so on. The authors developed an airborne repeat-pass INSAR system which can make very precise repeat-pass flights for interferometry. A method has been devised for getting the highly precise antenna motion using the phases from corner reflectors. In this paper, an outline of their airborne repeat-pass INSAR system, the method of measuring the precise antenna motion data and the first results in a test flight to verify the possibility of airborne repeat-pass INSAR are described.

Hidefumi Nagata

Papers

Synthetic aperture radar and target image production method

A new small airborne SAR based on Pi-SAR2

The NEC interferometric SAR system "NEC-SAR"

Development status of a new small airborne SAR based on Pi-SAR2

Airborne repeat-pass INSAR system