This paper summarizes the recent work in the fields of Synthetic Aperture Radar polarimetry and interferometry. These fields have seen very significant development during the last five years, and these fields are now well understood.

It is well known that, in the course of ionospheric propagation, the polarization state of radar signals is changed between transmitter and target, and again between target and receiver. For HF skywave radars, these changes may vary spatially and temporally in a quasi-random manner. When one wishes to determine the scattering matrix of a target, the presence of these unknown polarization transformations changes the nature of the inverse problem connecting received echoes with target scattering characteristics. Indeed, it is by no means obvious that the inverse problem is solvable. In this paper we demonstrate that, under certain realistic conditions, the scattering matrix can be estimated in the presence of a priori unknown polarization transformations in the propagation medium.

This contribution is concerned with the polarimetric characterization of monostatic backscattering and anti- monostatic forward scattering (transmission) described by homogeneous and inhomogeneous Sinclair and Jones matrices, respectively. A new inhomogeneity parameter for Jones matrices is presented and compared with others.

This contribution is concerned with coherent polarimetric bistatic scattering of plane electromagnetic waves from deterministic radar targets. The Huynen fork descriptor for the monostatic backscatter case describing the relations between optimal characteristic target polarizations on the Poincare sphere is extended to the bistatic scattering case by introducing a double Huynen fork for transmission and reception. The analysis relies on the singular value decomposition theorem.

The Poincare sphere of polarization points concept has been extended to the polarization and (spatial) phase sphere (the Pp sphere) by inclusion ofphase information when introducing the tangentialpolarization phasors. Tangential phasors represent polarization helices ofplane, monochromatic, completely polarized EM waves. Such helices, considered as models of waves, can be shifted with the velocity of light in two opposite directions along a propagation zaxis. Spatial phase of the wave has been defined by the position of the moving helix, in time t 0, versus the z-axis coordinates, independently of direction of wave's propagation. The double value of that spatial phase has been represented by the angle of phasor's orientation. It means that phasors rotate in time with angular velocity of 2a in two opposite direcüons depending on direction ofwave's propagation In the paper, the PP sphere is considered as a kind of the two-folded Riemann surface. The concept of the ONP PP basis is introduced and the orientation of their phasors explained, together with the rules of phasors' multiplication and addition. Mvantages of the proposed engineering notation are shown on examples of various transformations. In the Appendix some useful formulae of spherical trigonometry of special value for polarimetry are attached. Keywords: polarization sphere, Riemann surface, tangential phasor, polarization helix, polarization and phase vector

In microwave remote sensing, it is desirable to select radar antenna polarizations that maximize the contrast between two classes of scatterers or scatterer ensembles. A polarimetric radar measures complete polarization properties of a target and then provides a vector description of the resulting scattered wave through various target matrices. Several optimization procedures for the completely and partially polarized cases have been proposed based on the theory of radar polarimetry. It is the purpose of this paper to present optimization procedures for the enhancement of polarimetric contrast between two time-varying targets and to extend the procedure to two spatially incoherent image pixel targets. The targets are now characterized by the time-averaged or spatially-averaged Kronecker matrices, from which one can obtain the associated Graves and Kennaugh matrices. The Graves matrices of the targets are used to find a transmitter polarization to maximize the ratio of scattered power densities at the receiver. Using the Lagrange multiplier method, the maximization problem is cast into the form of a generalized Balois eigenvalue equation. The largest eigenvalue of the equation equals the maximal power ratio, and the optimal effective length of the transmitting antenna is proportional to the corresponding eigenvector. The Kennaugh matrices of the targets are employed to obtain the Kennaugh vectors of partially polarized scattered waves from the two targets. Each of the scattered Kennaugh vectors is decomposed into a completely polarized and an unpolarized part. It is well known that the power received from the unpolarized part is independent of the polarization characteristics of the receiving antenna. Then a receiver polarization is selected to maximize or minimize the completely polarized part scattered from the desired or the undesired target. As a numerical example, the optimal Stokes vectors of transmitting and receiving antennas are given to show the validity of the optimization procedures and how it can be applied to perfecting high resolution POL-SAR/SAL Image Feature Extraction.

In this paper we show how the entropy-alpha target decomposition scheme may be used for parametric inversion studies on particle clouds. The decomposition is first presented in detail and then applied to a 2-parameter model for backscatter from a random cloud of small anisotropic particles. The two parameters are the mean particle shape and the mean orientation angle of the cloud. An inversion algorithm is presented and applied to broad band polarimetric Radar data from the European Microwave Scattering Laboratory at JRC Ispra.

Classification of Earth terrain components within a full polarimetric SAR image is one of the most important applications of Radar Polarimetry in Remote Sensing. Unsupervised classification procedure, based around neural networks with competitive architecture, is applied to the full polarimetric SAR images of San Francisco Bay from the NASA/JPL AIRSAR data base (1988) for segmentation and clustering of different Earth terrain components. The linear feature vector used during the classification procedure is defined from a new scheme for parameterizing polarimetric scattering problems, which has application in the quantitative analysis of polarimetric SAR data. The method relies on an eigenvalue analysis of the coherency matrix and employs a 3-level Bernoulli statistical model to generate estimates of the average target scattering matrix parameters from the data.

A three-component (sphere, diplane, helix) decomposition of the complex Sinclair scattering matrix is described. Its application in relation to target characterization and identification is illustrated by applying the decomposition to fully polarimetric SAR data from the Danish EMISAR system.

Polarimetric synthetic aperture radar (SAR) has been successfully applied for, terrain and land-use classification, soil moisture and biomass measurements, and many other areas of remote sensing. However, its application to ocean and coastal areas has not been developed fully. This paper describes several remote-sensing applications for the littoral zone using polarimetric SAR. SIR-C L-band and C-band images are used for illustration.

This paper discusses the classification of target buried in the underground by the radar polarimetry. The subsurface radar is used in the detection of objects buried beneath the ground surface, such as archeological exploration, pipes, gas cables and cavities. However, in addition to target echo, the subsurface radar receives various echoes including clutter, because the underground is inhomogeneous medium. Therefore, the subsurface radar needs the ability to distinguish these echoes. In order to enhance the ability, we first applied the polarization anisotropy coefficient to classify the echo into isotropic target (plate, sphere) and anisotropic target (wire, pipe). It is easy to find the man- made target buried in the underground by polarization anisotropy coefficient. Second, we used a three-component decomposition technique for a scattering matrix. Third, we tried to classify targets using polarimetric signature approach. Moreover, the characteristic polarization state gives the oriented angle of anisotropic target. Therefore, these values contribute the classification of the target. The field experiments using an FM-CW radar system were carried out to show the usefulness of the radar polarimetry. In this paper, several detection and classification results are displayed. It is shown that these techniques improve the detection capability of buried target.

There is a great deal of interest in subsurface imaging of the earth's surface using SAR; however, most current and planned satellite SARs are not optimized for this purpose. Here we present a set of specifications for an earth-orbit satellite SAR specifically designed for subsurface imaging. In the design of a satellite borne ground penetrating SAR, there are several competing requirements all of which have to be balanced in a cost/benefit analysis. Here we look at two possible scenarios both using a 300 MHz carrier with one in a sun-synchronous orbit at 700 km altitude, the other at 250 km. Some of the critical parameters that are considered for this ground-penetrating SAR (n addition to those for a normal satellite SAR) include the wavelength, the dimensions of the real antenna, ground incidence angles and power density as well as polarization diversity. The intention here is to propose a system designed to maximize the subsurface back-scatter as a proportion of the total returned echo.

Continuous ULF background data are recorded at the Low Frequency Observatory in San Diego since 1990. Some 18 days preceding the large Northridge earthquake of January 17, 1994. Anomalous signals of approximately twice the background level were recorded. The timing of the anomalous signals, the return to normal levels after the quake and a delay in the onset of higher frequency anomalous signals all suggest a strong correlation of the anomalous signals with the events at Northridge. A simple model of migrating micro- fractures is used to explain the temporal characteristics of the signals.

Optimal algorithms of imaging extensive sources of intrinsic radioheat non-coherent radiation, and their electrophysical parameters and statistical characteristics (such as brightness and absolute temperatures, permittivity, means- square height and correlation radius of surface microirregularities, oil skin thickness etc.) estimation are studied in the case of constant surface parameters as well as in the case when values of parameters depend on surface coordinates. The peculiarity of these algorithms is that they are synthesized for a common case of wide- or superwide-band radiation detecting when the condition of spatial-temporal narrowbandness (quasi-monochromatic approximation) is broken. The algorithms are produced in the frame of maximum likelihood and maximum a posteriori probability density methods. indeterminacy functions of measuring systems are studied. Used mathematical apparatus is based on proposed transforms, that generalize the Fourier's, Laplace's and Fresnel's ones, as well as on proved theorems that extend the Van Zittert-Zernike theorem to the case of wide-band and superwide-band fields analysis.

In this paper we outline a general formulation of vector wave interferometry and then use this formulation to solve the optimization problem for interferometric coherence. We show that this problem can be reduced to a singular value decomposition of a non-symmetric complex matrix. We then develop a stochastic scattering model for an elevated forest canopy and use it to demonstrate application of the optimization scheme.

Speckle reduction of polarimetric SAR imagery has been studied using several different approaches. All these approaches exploited the degree of independence between HH, HV and VV channels. The statistical characteristics, such as correlation between channels, and polarimetric property preservation, were not addressed. This paper proposes a new approach in polarimetric SAR filtering. The new approach emphasizes not introducing cross-talk, preserving polarimetric information and statistical correlation between channels, and not degrading the image quality. To avoid cross-talk, each element of the covariance matrix has to be filtered independently. This rules out current methods of polarimetric SAR filtering. To preserve the polarimetric signature, each element of the covariance matrix should be filtered in a way similar to multi-look processing by averaging the covariance matrix of neighboring pixels, but without the deficiency of smearing edges, or degrading image quality. The proposed polarimetric SAR filter uses edge- directed non-square windows and applies the local statistics filter. The impact of using this polarimetric speckle filtering on terrain classification is also studied. NASA/JPL Les Landes polarimetric P-Band and C-Band SAR data is used for illustration.

The investigation presented in this paper demonstrates the potential of the combination of polarimetric and interferometric classification techniques for the extraction of map relevant features from space borne SAR data. In the first part we discuss a polarimetric classification technique based on Cloude's decomposition theorem. Afterwards we demonstrate the abilities of interferometric classification. The complementarity of the polarimetric and interferometric coherence based classification approaches can be used to resolve ambiguities that remain if one method is applied alone. The improvements results from their combination are available for an automatic classification and extraction of cartographic relevant features from space borne SAR data.

There are several important remote sensing applications where the development of Ground Penetrating Synthetic Aperture Radar (GPENSAR) is the logical approach, e.g., searching for buried military facilities, minefield mapping, survey of underground pipelines. Penetration of sufficient soil depth for useful results require a SAR to operate at VHF/UHF frequencies, e.g., 200 - 300 MHz. At these frequencies a satellite SAR will encounter substantial distortion in the double passage of the SAR signal through the ionosphere. One of the ionospheric distortions is equivalent the phase aberrations caused in imaging through the turbulent atmosphere, and the problem of phase retrieval for the GPENSAR becomes a necessity. For GPENSR there are imaging concepts that exploit dual polarization radiation of the SAR pulse. The phase retrieval problem then becomes one of compensation for the phase aberrations induced in each of the polarization components returned to the satellite receiver. We discuss the use of the two polarizations to cancel the ionospheric phase aberrations. Unfortunately, the resulting signal has only relative phase of the two polarizations. We discuss an algorithm for the retrieval of the absolute phase. The algorithm is based on an optimization approach. Although phase retrieval by optimization is difficult because of local minima, the retrieval of absolute phase in the dual polarization case is substantially less difficult, because the two polarizations constrain the solution sufficiently to eliminate many local minima.

A new remote sensing technique using polarimetric synthetic aperture radar (SAR) data has been developed which can measure terrain slopes in the azimuthal, or along-track, direction. Terrain elevation maps can then be generated by integrating these slopes. The processing of both single- pass, and orthogonal two-pass, datasets is investigated. When single-pass SAR data is used elevation groundtruth must be available for at least one point of each profile formed in the azimuthal direction. When orthogonal two-pass slope data is employed, the elevation surface may be generated as an iterative solution of the Poisson equation and only a single elevation tie-point is required. The study presented uses orthogonal two-pass NASA/JPL AIRSAR P-band data as a test of the Poisson equation approach for an area in Death Valley National Park, California. The orthogonal two-pass results have been compared with a co-registered, conventional, U.S. Geological Survey product. Technique accuracy and potential applications are discussed.

Recently, estimation and resolution improvements utilizing the polarization information of electromagnetic wave have been attracting attention in remote sensing and indoor radio propagation analyses. High-resolution technique based on the modern spectral estimation method is one of the promising methods to realize high resolution and accurate estimation capabilities. Several modifications for the technique using the polarization data have reported. In this paper, we propose a new modification for the technique concerning with decorrelation preprocessings, and show its availability for microwave imaging. The method has two main advantages compared with the conventional one; (1) improved decorrelation performance, (2) increased the number of resolvable signals (scattering centers). The resolution improvement is verified theoretically and experimentally.

The detection of ice layers on road surfaces is a crucial requirement for a system that is designed to warn vehicle drivers of hazardous road conditions. In the millimeter wave regime at 76 GHz the dielectric constant of ice and conventional road surface materials (i.e. asphalt, concrete) is found to be nearly similar. Thus, if the layer of ice is very thin and thus is of the same shape of roughness as the underlying road surface it cannot be securely detected using conventional algorithmic approaches. The method introduced in this paper extents and applies the theoretical work of Pancharatnam on the superposition of polarized waves. The projection of the Stokes vectors onto the Poincare sphere traces a circle due to the variation of the thickness of the ice layer. The paper presents a method that utilizes the concept of wave superposition to detect this trace even if it is corrupted by stochastic variation due to rough surface scattering. Measurement results taken under real traffic conditions prove the validity of the proposed algorithms. Classification results are presented and the results discussed.

The NASA/JPL Airborne Synthetic Aperture Radar system (AIRSAR) has been in operation since 1988. The original radar configuration consisted of PIL/C-band quadpolarization mode in both 20 MHz and 40 MHz chirp bandwidths. Over the years, we have added the L- and C-band along track interferometry mode (ATI), the on-board processor, the C-band cross-track interferometry mode (XTI) in 199 1 , and the L-band XTI mode in 1995. In addition, we also replaced the GPS receiver as well as the inertial navigation system in 1995 to improve the accuracy of motion compensation and geolocation of the output products. In the 1996 PacRim Campaign, we flew a new digital chirp generator that has significantly better chirp linearity, which should improve the ISLR of the output images. In this paper, we will briefly describe the instrument characteristics, the evolution of the various radar modes, the instrument performance and improvement in the knowledge of the positioning and attitude information of the radar. In addition, we will summarize the progress of the data processing effort especially in the interferometry processing. Finally, we will address the issue of processing and calibrating the cross-track interferometry (XTI) data.

Symmetry in a target gives related properties to the electromagnetic scattering. Emphasizing targets on or below the surface of the ground (or water), this paper considers symmetry in the context of magnetic singularity identification (utilizing low-frequency diffusion in metal targets) and electro-magnetic singularity identification (utilizing a ground-penetrating radar with wavelengths of the order of the dimensions of the metal and/or dielectric targets). It is found that the presence of various target symmetries can be detected and that this can potentially be used as a target discriminant (a first-order cut) for concentrating ones attention on more interesting targets (for further analysis and/or destruction).

For certain remote sensing applications millimeterwaves offer advantages over lower frequency radar bands and infrared systems. In comparison to the IR-region the most important advantages is the good all weather capability. With respect to the microwave radar bands mainly the coupling of millimeterwaves to small surface structures is significant. One very special item, typical for the use of millimeterwaves is the determination of signatures of the ocean surface where the small scale structures of the wave patterns of different origin give reason for its dynamic variation. To generate high resolution images the synthetic aperture approach is the favorite method also for the millimeterwave bands. These wavelengths allow some simplifications in the algorithms to be applied, namely the image distortions due to range migration and depth of focus can be neglected. The short aperture time which is reduced by the factor of the wavelength for an equal cross range resolution, leads to a much lesser influence of flight instabilities of the airborne platform, than have to be taken into account for classical microwave SAR. Additionally the image displacement of moving structures is less critical at millimeterwaves, as in SAR imaging this displacement is directly proportional to the aperture time. The polarimetric, high resolution experimental radar MEMPHIS (Millimeterwave Experimental Multifrequency Polarimetric High Resolution Imaging System) with simultaneous operating front-ends at 35 GHz and 94 GHz has been installed onboard a cargo aircraft in side-looking configuration. The paper describes the system configuration and the SAR processing algorithm and gives representative results for the generated radar images, compares the results at 35 and 94 GHz and illustrates techniques for signature enhancement by use of the polarimetry.

`WISIP: Wideband ((mu) Hz - PHz) Interferometric Sensing and Imaging Polarimetry' has become an important, indispensable tool in wide area military battlespace surveillance and global environmental stress change monitoring of the terrestrial and planetary covers. It enables dynamic, real- time optimal features extraction of significant characteristics of desirable targets and/or target sections with simultaneous suppression of undesirable background clutter and propagation path speckle at hitherto unknown clarity and never before achieved quality. `WISIP' may be adopted to the Detection, Recognition and Identification (DRI) of any stationary, moving or vibrating target or distributed scatterer segments versus arbitrary stationary, dynamically changing and/or moving geo-physical/ecological environments, provided the instantaneous 2 X 2 phasor (Jones/Sinclair) and 4 X 4 power density (Mueller/Kennaugh) matrices for forward- propagation/backward-scattering, respectively, can be measured with sufficient accuracy. For example, the DRI of stealthy, dynamically moving and/or camouflaged stationary objects occluded deeply into heterogeneous stationary and/or dynamically moving inhomogeneous volumetric scatter environments such as precipitation scatter, the ocean sea/lake surface boundary layers, the littoral coastal surf zones, pack-ice and snow or vegetation canopies, dry sands and soils, etc., can now be successfully realized. A comprehensive overview is presented on how these modern high resolution/precision, complete polarimetric coregistered signature sensing and imaging techniques, complemented by full integration of novel navigational electronic tools, such as DGPS, will advance electromagnetic vector wave sensing and imaging towards the limits of physical realizability. Various examples utilizing most recent image data take sets of the NAWC/ERIM-P3-UWB-TOPIF'E-CATI/LTBL- POLSAR and NASA-JPL-AIRSAR airborne, the NASA/DARA/DASI-SIR- C/X-SAR shuttle, and the ESA ERS-1/2, JERS and RADARSAT satellite imaging systems will be presented for demonstrating the utility of WISIP.

This contribution is concerned with the theory of optical and radar polarimetry dealing with forward (transmission) and backscatter polarimetric scattering. Characteristic similarities and differences between these topics are pointed out and typical polarimetric invariants are identified.

We present an algorithm which decomposes a Mueller matrix into a sequence of three matrix factors: a diattenuator, followed by a retarder, then followed by a depolarizer. Those factors are unique except for singular Mueller matrices. Based upon this decomposition, the diattenuation and retardance of a Mueller matrix can be defined and computed. Thus, this algorithm is useful for performing data reduction upon experimentally determined Mueller matrices.

Recent findings in a number of laboratories suggest that there are two classes of polarization sensitivity (PS) in fish, and perhaps in other vertebrates as well. One class shows orthogonal PS only in the UV spectrum (salmonids) while the other shows PS in the long-wavelength spectrum (sunfishes). Presumably, this diversity in PS systems implicates a more variable function of PS; such as contrast enhancement and spatial orientation. The work in my laboratory centers on the role of UV cones in PS and orientation behavior. Some salient findings include: (1) salmonids have four cone pigments which overlap in the UV spectrum, (2) electrophysiological measurements of PS indicate the presence of orthogonal PS in the UV spectrum, and (3) spatial orientation behavior of salmonids requires UV light. Single-unit recording in the CNS reveals that polarization, sensitive ganglion cells project to the torus semicicularis not the optic tectum as indicated in the previous studies. I will present evidence that single neurons in the torus are capable of coding the e-vector of incident plane polarized light. Presumably, these neurons play a role in mediating polarized light guided behavior in fish, like object detection/recognition and spatial orientation in the aquatic environment.

WISIP: Wideband QiHz -PHz) Interferometric Sensing and Imaging Polarimetry has become an indispensable tool for wide area military battlespace surveillance and global geo/eco-environmental stress change monitoring of the terrestrial and planetary covers. It enables dynamic, real-time optimal feature extraction of significant characteristics of desirable targets and/or target sections with simultaneous suppression of undesirable background clutter and propagation path speckle at hitherto unknown clarity and never-before-achieved quality. WISIP may be adapted to the Detection, Recognition and Identification (DRI) of any stationary, moving or vibrating target or distributed scatterer segments versus arbitrary stationary, dynamically changing and/or moving geo-physical/ecological environments, provided the instantaneous 2x2 phasor (Jones/Sinclair) and 4x4 powerdensity (Mueller/Kennaugh) matrices for forward-propagation/backward-scattering, respectively, can be measured with sufficient accuracy. For example, the DRT of stealthy, dynamically moving and/or camouflaged stationary objects occluded deeply into heterogeneous stationary and/or dynamically moving inhomogeneous volumetric scatter environments such as precipitation scatter, the ocean sea/lake surface boundary layers, the littoral coastal surf zones, pack-ice and snow or vegetative canopies, dry sands and soils, etc., can now be successfully realized

During the past decade, two seemingly independent imaging sciences have advanced to maturity (I) Wideband (SAR) Polarimetry (UWB-POL-SAR), as discussed in Part I ofthese SPIE 3 120 Conference Proceedings, and (ii) Topographic Interferometric SAR (TOP-InSAR), which has become of considerable interest in Digital Elevation Mapping (DEM). In addition, with the rapid perfection ofDifferential Global electronic satellite Positioning Systems (D-GPS), Repeat-Pass Differential Interferometric SAR (RP-D-InSAR) has been realized with satellite (ERS-112, JERS) and airborne dual-antenna interferometer SAR systems (NASA-JPL-TOP-SAR, DCRS EMI-SAR; DLR-E-SAR, EREM-IFSAR, NAWC-QUAD-SAR, etc.)1'2. In conceptually extending generalized vector (polarization) holography, it follows directly that the complete utilization of polarimetric (dual channel: scattering matrix) radar (SAR) systems should strongly improve on the performance ofboth single-platform dual antennas and on repeat-pass (long-temporal baseline) radar (SAR) interferometry3. The benefits are two-fold in that polarimetric speckle reduction can be achieved, by means of the polarization-extended "Lee filter" of Jong-Sen Lee and coworkers at NRL-RSD/ISS, and interferometric phase coherence can strongly be enhanced with the implementation of Cloude's PIPCO (Polarimetric Interferometric Phase Coherence Optimization) algorithm. This is being demonstrated in papers by Cloude and Papathanassiou at DLR-Oberpfaffenhofen in coordination with Lee, Ainsworth, Schuler and coworkers ofNRL-RSD/ISS, Washington, DC, utilizing one ofthe ideally-matching repeat-pass pairs of the recent SIR-C/X-SAR Mission 2, Tien-San Tracks 122.20 (94 Oct. 08) and 154.20 (94 Oct. 09) L/C-band POL-D-InSAR Image Overlays within the Russian Academy of Sciences, Siberian Division, Buriat Natural Sciences Center (RAS-SDBNSC) SE Baikal Lake, Selenga Delta geo/eco-environmental Sanctuary, the "Kudara Polygon" for which various institutes ofthe RAS-SD-BNSC have collected extensive geographic (geo-ecological and geo-tectonic environmental information and vegetative/eco-agriculture, forestry, urbanization, wildlife and fisheries, etc.) groundtruth data over the past several decades2. By coincidence, this tectonically active region ofthe Kudara Polygon lies within the Mid-Asian Baikal Tectonic Rift Zone of the Hovsogol/Mongolia - Baikal/BuriatiaLakes Basin; and is hence well-suited for serving as a test site for developing RPPOL-D-InSAR technology by implementation ofvarious image feature characterization algorithms such as Cloude-Pottier polarimetric "Entropy versus Anisotropy (H-ct) " andthe Cloude-Papathanassiou PIPCO concepts. Part II ofthese SPIE 3 120 Conference Proceedings contains the first complete records ofthis impressive advancement accomplished in spaceborne RP-POL-D-InSAR during the past three years.

An engineering approach has been applied to the theory of radar polarimetry. It offers numerous advantages in analyzing propagation and scattering ofpolarized waves. It is based on introduction of two mutually conjugate 2-dim. complex spaces of the polarization and phase (PP) vectors and on application of the matrix calculus to the transmission equations when using the exactly defined PP bases. The PP vectors of waves and antennas, including their PP basis vectors, are considered as phasors tangent to the polarization sphere. Keywords: radar polanmetry, bistatic scauering, polarization and phase vector, tangential phasor

Network theoiy of microive four-ports has been extended to the domain of completely polarized fields of electromagnetic plane waves to obtain the theory of two-ports applicable for millimeter waves and optical polarimetry. For that purpose, incoming and outgoing waves in two ports on each side of the four-port have been combined to create the directional Jones vectors3. Their transformation by two reflectance and two transmittance Sinclair matrices is considered. Then, directIons of the propagation z-axes at one and both ports have been reversed by rotation of the spatial coordinate system, enabling one formation of two transmittance Jones matrices, what allowed for introduction of cascading matrices of the whole polarimetric two-port. Considerations are limited to the losses and reciprocal systems. Mutual dependencies between elements of Sinclair matrices are presented. A geometrical model of the scattering matrix of the whole two-port has been build up. It is of the form of four polarization spheres of tangential .2 Each sphere represents one of four Sinclair matrices. Its diameter, the inversion point, and the rotation after inversion axis and angle are given, shape and orientation of the polarization fork determined, and some special incident polarizations specified. Keywords: polarimetric two-ports, scattering matrices. geometric models, cascading matrices

The effect of Faraday rotation on spaceborne polarimetric SAR measurements is addressed. Single-polarized, dual- polarized and quad-polarized backscatter measurements subject to Faraday rotation are modeled. It is shown that due to Faraday rotation, the received signal includes other polarization characteristics of the surface. Techniques are developed to detect the presence of Faraday rotation in dual-polarized and quad-polarized SAR data. Finally, a novel approach for the correction (or calibration) of linearly polarized fully polarimetric data for Faraday rotation, to recover the `true' scattering matrix, is presented.

In polarimetric remote sensing, one can use the symmetric 2 X 2 backscattering dyadic to obtain information concerning the target. When operating at a single frequency, however, the amount of information is limited and there is an ambiguity in applying simple scattering models to the data. By extending the bandwidth in the sense of a pulse or multiple frequencies (retaining phase) more information concerning the target can be obtained, to which more sophisticated scattering models can be applied. In the form of the temporal backscattering dyadic (operator), temporal isolation via windows can also be used to separate scattering events for separate analysis.