IEEE Transactions on Antennas and Propagation, 2000
Page 1. 86 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 48, NO. 1, JANUARY 2000 Compensati... more Page 1. 86 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 48, NO. 1, JANUARY 2000 Compensation for the Effects of Mutual Coupling on Direct Data Domain Adaptive Algorithms Raviraj S. Adve, Member, IEEE, and Tapan Kumar Sarkar, Fellow, IEEE ...
IEEE Transactions on Microwave Theory and Techniques, 1997
In this paper, it is shown that Cauchy's method can be used effectively to interpolate/extrapolat... more In this paper, it is shown that Cauchy's method can be used effectively to interpolate/extrapolate narrow-band system responses. The given information can either be theoretical datapoints or measured experimental data over a band. For theoretical data extrapolation or interpolation, the sampled values of the function and, optionally, a few of its derivatives have been used to reconstruct the function. For measured data, only measured values of the parameter are used to create broadband information from limited data as derivative information is too noisy. Cauchy's method assumes that the parameter to be extrapolated/interpolated, as a function of frequency, is a ratio of two polynomials. The problem is to determine the order of the polynomials and the coefficients therein. The method of total least squares (TLS) has been used to solve the resulting matrix equation involving the coefficients of the polynomials. Typical numerical results have been presented to show that reliable interpolation/extrapolation can be done for various system responses.
Sarkar, T. K., Park, S., Koh, J., and Schneible, R. A., A Deterministic Least Squares Approach to... more Sarkar, T. K., Park, S., Koh, J., and Schneible, R. A., A Deterministic Least Squares Approach to Adaptive Antennas,Digital Signal Processing6 (1996), 185–194.A direct data domain approach to adaptively receiving a signal coming from a given direction in the presence of strong jammers and clutter is presented. In conventional adaptive algorithms, the statistical approach is based on forming an estimate of the covariance matrix of the received antenna voltages (measured voltages at the antenna terminals) without the signal. In this article, first a review of the conventional approaches is presented, where the number of adaptive weights is usually equal to the number of antenna elements. The equations for solutions of the weights are then generated by performing an averaging in time. This makes it possible to handle the unequally spaced antenna case (as in MUSIC). Unfortunately this methodology cannot handle coherent jammers (which may be due to multipath effects) or cases where the noise statistics change quite rapidly. To mitigate the above problems this article presents a direct data domain approach to the adaptive problem, where an equation error is minimized. This is ideally suited to a highly nonstationary environment, particularly in the presence of blinking jammers and for problems where the clutter characteristics change quite rapidly. Hence the processing in the data domain is done on a snapshot-by-snapshot basis. Two new direct data domain approaches are presented. One is based on the computation of a generalized eigenvalue for the signal strength, and the other is based on the solution of a set of block Hankel matrix equations. Since the system matrix has a block Hankel structure, the conjugate gradient method and the Fast Fourier transform can be utilized for efficient solution of the adaptive problem in hardware in real time. Also a methodology which prevents signal cancellation when the direction of arrival is not known precisely is presented. Limited examples are presented to illustrate the efficacy of this technique.
IEEE Transactions on Antennas and Propagation, 1997
Page 1. IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 45, NO. 1, JANUARY 1997 147 Extrapola... more Page 1. IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 45, NO. 1, JANUARY 1997 147 Extrapolation of Time-Domain Responses from Three-Dimensional Conducting Objects Utilizing the Matrix Pencil Technique ...
IEEE Transactions on Microwave Theory and Techniques, 1994
Resistance and Inductance per Unit Length of ... Antonije R. DjordjeviC and Tapan K. Sarkar, Fell... more Resistance and Inductance per Unit Length of ... Antonije R. DjordjeviC and Tapan K. Sarkar, Fellow, IEEE ... Abstract-Based on numerical results obtained from solutions to integral equations, other numerical results and theoretical considerations, a set of closed-form ...
IEEE Transactions on Microwave Theory and Techniques, 1991
Page 1. 1090 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 39, NO. 7, JULY 1991 On t... more Page 1. 1090 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 39, NO. 7, JULY 1991 On the Modeling of Conductor and Substrate Losses in Multiconductor, Multidielectric Transmission Line Systems ...
Page 1. Time-Domain Response of Multiconductor I ransmlssron Lines ANTONIJE R. DJORDJEVIC, TAPAN ... more Page 1. Time-Domain Response of Multiconductor I ransmlssron Lines ANTONIJE R. DJORDJEVIC, TAPAN K. SARKAR, SENIOR MEMBER, IEEE, AND ROGER F. HARRINGTON, FELLOW, IEEE Evaluation of the time-domain ...
IEEE Transactions on Electromagnetic Compatibility, 1993
Page 1. 134 IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY, VOL. 35, NO. 2, MAY 1993 An Inves... more Page 1. 134 IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY, VOL. 35, NO. 2, MAY 1993 An Investigation of Delta4 Noise on Integrated Circuits Antonije R. DjordjeviC and Tapan Kumar Sarkar, Fellow, ZEEE ...
IEEE Transactions on Microwave Theory and Techniques, 1990
Page 1. 1568 Il-EE TRANSACTIONS ON MICKOWAVE THEOKY AND TECHNIQUES, VOL. 38, NO. 11, NOVEMBER 199... more Page 1. 1568 Il-EE TRANSACTIONS ON MICKOWAVE THEOKY AND TECHNIQUES, VOL. 38, NO. 11, NOVEMBER 1990 Electromagnetic Scattering and Radiation from Finite Microstrip Structures TAPAN K. SARKAR, SENIOR ...
IEEE Transactions on Antennas and Propagation, 1989
Page 1. IEEE TRANSACTIONS ON ANTENNAS AND PROPAGAIION. VOL. 37. YO 5. MA) 1989 673 Communication ... more Page 1. IEEE TRANSACTIONS ON ANTENNAS AND PROPAGAIION. VOL. 37. YO 5. MA) 1989 673 Communication Electromagnetic Scattering from Dielectric Bodies TAPAN K. SARKAR. SENIOR MEMBER. IEEE, ERCUMENT ...
IEEE Transactions on Antennas and Propagation, 2000
Page 1. 86 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 48, NO. 1, JANUARY 2000 Compensati... more Page 1. 86 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 48, NO. 1, JANUARY 2000 Compensation for the Effects of Mutual Coupling on Direct Data Domain Adaptive Algorithms Raviraj S. Adve, Member, IEEE, and Tapan Kumar Sarkar, Fellow, IEEE ...
IEEE Transactions on Microwave Theory and Techniques, 1997
In this paper, it is shown that Cauchy's method can be used effectively to interpolate/extrapolat... more In this paper, it is shown that Cauchy's method can be used effectively to interpolate/extrapolate narrow-band system responses. The given information can either be theoretical datapoints or measured experimental data over a band. For theoretical data extrapolation or interpolation, the sampled values of the function and, optionally, a few of its derivatives have been used to reconstruct the function. For measured data, only measured values of the parameter are used to create broadband information from limited data as derivative information is too noisy. Cauchy's method assumes that the parameter to be extrapolated/interpolated, as a function of frequency, is a ratio of two polynomials. The problem is to determine the order of the polynomials and the coefficients therein. The method of total least squares (TLS) has been used to solve the resulting matrix equation involving the coefficients of the polynomials. Typical numerical results have been presented to show that reliable interpolation/extrapolation can be done for various system responses.
Sarkar, T. K., Park, S., Koh, J., and Schneible, R. A., A Deterministic Least Squares Approach to... more Sarkar, T. K., Park, S., Koh, J., and Schneible, R. A., A Deterministic Least Squares Approach to Adaptive Antennas,Digital Signal Processing6 (1996), 185–194.A direct data domain approach to adaptively receiving a signal coming from a given direction in the presence of strong jammers and clutter is presented. In conventional adaptive algorithms, the statistical approach is based on forming an estimate of the covariance matrix of the received antenna voltages (measured voltages at the antenna terminals) without the signal. In this article, first a review of the conventional approaches is presented, where the number of adaptive weights is usually equal to the number of antenna elements. The equations for solutions of the weights are then generated by performing an averaging in time. This makes it possible to handle the unequally spaced antenna case (as in MUSIC). Unfortunately this methodology cannot handle coherent jammers (which may be due to multipath effects) or cases where the noise statistics change quite rapidly. To mitigate the above problems this article presents a direct data domain approach to the adaptive problem, where an equation error is minimized. This is ideally suited to a highly nonstationary environment, particularly in the presence of blinking jammers and for problems where the clutter characteristics change quite rapidly. Hence the processing in the data domain is done on a snapshot-by-snapshot basis. Two new direct data domain approaches are presented. One is based on the computation of a generalized eigenvalue for the signal strength, and the other is based on the solution of a set of block Hankel matrix equations. Since the system matrix has a block Hankel structure, the conjugate gradient method and the Fast Fourier transform can be utilized for efficient solution of the adaptive problem in hardware in real time. Also a methodology which prevents signal cancellation when the direction of arrival is not known precisely is presented. Limited examples are presented to illustrate the efficacy of this technique.
IEEE Transactions on Antennas and Propagation, 1997
Page 1. IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 45, NO. 1, JANUARY 1997 147 Extrapola... more Page 1. IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 45, NO. 1, JANUARY 1997 147 Extrapolation of Time-Domain Responses from Three-Dimensional Conducting Objects Utilizing the Matrix Pencil Technique ...
IEEE Transactions on Microwave Theory and Techniques, 1994
Resistance and Inductance per Unit Length of ... Antonije R. DjordjeviC and Tapan K. Sarkar, Fell... more Resistance and Inductance per Unit Length of ... Antonije R. DjordjeviC and Tapan K. Sarkar, Fellow, IEEE ... Abstract-Based on numerical results obtained from solutions to integral equations, other numerical results and theoretical considerations, a set of closed-form ...
IEEE Transactions on Microwave Theory and Techniques, 1991
Page 1. 1090 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 39, NO. 7, JULY 1991 On t... more Page 1. 1090 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 39, NO. 7, JULY 1991 On the Modeling of Conductor and Substrate Losses in Multiconductor, Multidielectric Transmission Line Systems ...
Page 1. Time-Domain Response of Multiconductor I ransmlssron Lines ANTONIJE R. DJORDJEVIC, TAPAN ... more Page 1. Time-Domain Response of Multiconductor I ransmlssron Lines ANTONIJE R. DJORDJEVIC, TAPAN K. SARKAR, SENIOR MEMBER, IEEE, AND ROGER F. HARRINGTON, FELLOW, IEEE Evaluation of the time-domain ...
IEEE Transactions on Electromagnetic Compatibility, 1993
Page 1. 134 IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY, VOL. 35, NO. 2, MAY 1993 An Inves... more Page 1. 134 IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY, VOL. 35, NO. 2, MAY 1993 An Investigation of Delta4 Noise on Integrated Circuits Antonije R. DjordjeviC and Tapan Kumar Sarkar, Fellow, ZEEE ...
IEEE Transactions on Microwave Theory and Techniques, 1990
Page 1. 1568 Il-EE TRANSACTIONS ON MICKOWAVE THEOKY AND TECHNIQUES, VOL. 38, NO. 11, NOVEMBER 199... more Page 1. 1568 Il-EE TRANSACTIONS ON MICKOWAVE THEOKY AND TECHNIQUES, VOL. 38, NO. 11, NOVEMBER 1990 Electromagnetic Scattering and Radiation from Finite Microstrip Structures TAPAN K. SARKAR, SENIOR ...
IEEE Transactions on Antennas and Propagation, 1989
Page 1. IEEE TRANSACTIONS ON ANTENNAS AND PROPAGAIION. VOL. 37. YO 5. MA) 1989 673 Communication ... more Page 1. IEEE TRANSACTIONS ON ANTENNAS AND PROPAGAIION. VOL. 37. YO 5. MA) 1989 673 Communication Electromagnetic Scattering from Dielectric Bodies TAPAN K. SARKAR. SENIOR MEMBER. IEEE, ERCUMENT ...
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