In this study, the angle ambiguity of a single baseline is analyzed to design an antenna baseline for an interferometric radar altimeter (IRA). To overcome the shortcoming of a single baseline in which angle ambiguity occurs during every phase period, the IRA adopts multiple baselines for its antenna and estimates the target angle by employing the phase comparison monopulse algorithm. However, the problem with multiple baselines is that an angle ambiguity that is difficult to solve by signal processing occurs when the phase error is large. To minimize this problem at the antenna design stage, the angle ambiguity is analyzed according to the phase error and the baseline spacing. The analysis is performed by conducting a parameter study based on the Monte Carlo simulation, and the validity of the analysis is verified from the test data.

We present a simulation study of an algorithm for the range and angle of arrival(AOA) estimation with an interferometric synthetic aperture radar(InSAR) altimeter using a real digital elevation model(DEM). We also illustrate a step-by-step procedure of generating raw InSAR data, as well as their range and azimuth compressed data, which is to be used for the subsequent altitude and angle estimation. The AOA is estimated using a deterministic maximum likelihood estimator(DMLE) applied to the first arrived point for each pulse in the compressed data obtained with three antennas. The range bin size and the pulse repetition interval(PRI) are much smaller than the cell size of the DEM used in this study. To make the DEM compatible to the radar parameters, we first generate a higher resolution DEM by linearly interpolating the given DEM. After a brief description of the principle of the InSAR altimeter, the algorithms for altitude and angle estimation are presented, and their performance is assessed through simulation.

We present an implementation result of a computer GUI-based simulator using MATLAB to verify the performance of interferometric radar altimeter(IRA) which is possible to measure the slant range altitude and the cross-track angle to the nearest point for terrain aided navigation(TAN). After a brief description of the principle of TAN and IRA, we present that the grids are divided for the modeling of the reflected signal in digital elevation map(DEM) and so the radar cross section(RCS) of each grid is calculated and the signal-noise ratio(SNR) of the reflected signal in the radar beam width. And the signal processing procedures of the IRA and the structure of the IRA simulator are shown.

A dual‐frequency dual‐polarization (DFDP) antenna of high isolation between two ports with embedded 2 × 1 mushroom‐like electromagnetic bandgap (EBG) cells is presented. The equivalent circuit of a suspended microstrip line over 2 × 1 EBG cells is introduced. The numerical analysis from the equivalent circuit and measured results show that the microstrip line with embedded EBG cells has a distinctive and sharp rejection band that provides near 0 dB insertion loss outside the rejection band. By embedding the EBG cells under feedlines of a DFDP antenna, the isolation between two ports of the proposed antenna is enhanced by more than 20 dB, when compared with that of a conventional DFDP antenna. The proposed DFDP antenna is fabricated and measured. The simulated and measured results show a good agreement. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1764–1768, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22513

In this paper, a method of ISAR geometric calibration is represented by using impulse-radio UWB radar. The ir-UWB is good for using a signal processing in time domain, so, it does not occur a multi-path or coupling problem. If a signal that between antennas and target is assumed a plane wave, a center of rotation in ISAR geometry model can be estimated by using point target. Before image is reconstructed with sinogram, the center of rotation can be calculated by using least square fitting. This method can be obtained a more contrast image, and a maximum value of entropy of image. The method, that estimates a center of rotation in received data, will be used a initial setup of instruments or a periodic compensation to reconstruct image. It would be useful in medical, security and surveillance imaging equipments that have a fixed geometry.