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Antennas and RF components designed with graded index composite materials

July 27, 2020
  |
Conference Paper
Author:
Roberto G. Rojas-Teran
…
Published in:
2020 Intnl. Applied Computational Electromagnetics Society Symp., ACES, 27-31 July 2020.
Topic:
additive manufacturing
R&D area:
R&D group:

Summary

Antennas and RF components in general, can greatly benefit with the recent development of low-loss 3D print graded index materials. The additional degrees of freedom provided by graded index materials can result in the design of antennas and other RF components with superior performance than currently available designs based on conventional constant permittivity materials. Here we discuss our work designing flat lenses for antennas and RF matching networks as well as filters based on graded index composite materials.
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Summary

Antennas and RF components in general, can greatly benefit with the recent development of low-loss 3D print graded index materials. The additional degrees of freedom provided by graded index materials can result in the design of antennas and other RF components with superior performance than currently available designs based on...

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Antennas and RF components designed with graded index composite materials

Wind turbine interference mitigation using a waveform diversity radar

April 27, 2017
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Journal Article
Author:
Steven I. Krich
…
Published in:
IEEE Trans. Aerosp. Electron. Syst., Vol. 53, No. 2, April 2017, pp. 805-15.
Topic:
radar
R&D area:
R&D group:

Summary

Interference from the proliferation of wind turbines is becoming a problem for ground-based medium-to-high pulse repetition frequency (PRF) pulsed–Doppler air surveillance radars. This paper demonstrates that randomizing some parameters of the transmit waveform from pulse to pulse, a filter can be designed to suppress both the wind turbine interference and the ground clutter. Furthermore, a single coherent processing interval (CPI) is sufficient to make an unambiguous range measurement. Therefore, multiple CPIs are not needed for range disambiguation, as in the staggered PRFs techniques. First, we consider a waveform with fixed PRF but diverse (random) initial phase applied to each transmit pulse. Second, we consider a waveform with diverse (random) PRF. The theoretical results are validated through simulations and analysis of experimental data. Clutter-plus-interference suppression and range disambiguation in a single CPI may be attractive to the Federal Aviation Administration and coastal radars.
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Summary

Interference from the proliferation of wind turbines is becoming a problem for ground-based medium-to-high pulse repetition frequency (PRF) pulsed–Doppler air surveillance radars. This paper demonstrates that randomizing some parameters of the transmit waveform from pulse to pulse, a filter can be designed to suppress both the wind turbine interference and...

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Wind turbine interference mitigation using a waveform diversity radar

Comparisons between the extended Kalman filter and the state-dependent Riccati estimator

September 1, 2014
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Journal Article
Author:
Andrew M. Berman
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Published in:
J. Guid. Control Dyn., Vol. 37, No. 5, September-October 2014, pp. 1556-67.
Topic:
electronic warfare
R&D area:
R&D group:

Summary

The state-dependent Riccati equation-based estimator is becoming a popular estimation tool for nonlinear systems since it does not use system linearization. In this paper, the state-dependent Riccati equation-based estimator is compared with the widely used extended Kalman filter for three simple examples that appear in the open literature. It is demonstrated that, by simulation, the state-dependent Riccati equation-based estimator at best has comparable results to the extended Kalman filter but is often worse than the extended Kalman filter. In some cases, the state-dependent Riccati equation-based estimator does not converge, even though the system considered satisfies all the mathematical constraints on controllability and observability. Sufficient detail is presented in the paper so that the interested reader cannot only duplicate the results but perhaps make suggestions on how to get the state-dependent Riccati equation-based estimator to perform better.
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Summary

The state-dependent Riccati equation-based estimator is becoming a popular estimation tool for nonlinear systems since it does not use system linearization. In this paper, the state-dependent Riccati equation-based estimator is compared with the widely used extended Kalman filter for three simple examples that appear in the open literature. It is...

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Comparisons between the extended Kalman filter and the state-dependent Riccati estimator

MIMO radar theory and experimental results

November 7, 2004
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Conference Paper
Author:
Frank C. Robey
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Published in:
38th Asilomar Conf. on Signals, Systems and Computers, Vol. 2, 7-10 November 2004, pp. 300-304.
Topic:
radar
R&D area:
R&D group:

Summary

The continuing progress of Moore's law has enabled the development of radar systems that simultaneously transmit and receive multiple coded waveforms from multiple phase centers and to process them in ways that have been unavailable in the past. The signals available for processing from these Multiple-Input Multiple-Output (MIMO) radar systems appear as spatial samples corresponding to the convolution of the transmit and receive aperture phase centers. The samples provide the ability to excite and measure the channel that consists of the transmit/receive propagation paths, the target and incidental scattering or clutter. These signals may be processed and combined to form an adaptive coherent transmit beam, or to search an extended area with high resolution in a single dwell. Adaptively combining the received data provides the effect of adaptively controlling the transmit beamshape and the spatial extent provides improved track-while-scan accuracy. This paper describes the theory behind the improved surveillance radar performance and illustrates this with measurements from experimental MIMO radars.
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Summary

The continuing progress of Moore's law has enabled the development of radar systems that simultaneously transmit and receive multiple coded waveforms from multiple phase centers and to process them in ways that have been unavailable in the past. The signals available for processing from these Multiple-Input Multiple-Output (MIMO) radar systems...

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MIMO radar theory and experimental results

Wideband aperture coherence processing for next generation radar (NexGen)

July 30, 2004
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Project Report
Author:
Kevin M. Cuomo
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Published in:
MIT Lincoln Laboratory Report NG-3
Topic:
radar
R&D area:
R&D group:

Summary

This report develops robust signal processing architectures and algorithms specifically designed to achieve multi-aperture coherence on transmit and receive. A key feature of our approach is the use of orthogonal radar waveforms that allow the monostatic and bistatic target returns to be separated at each receiver's matched filter output. By analyzing these returns, we may determine the appropriate transmit times and phases in order to cohere the various radar apertures using both narrowband and wideband waveforms. This process increases the array gain on receive to N2 instead of N for the single transmitter case. Furthermore, when hll coherence on transmit is achieved, the array gain is N3. The performance of our coherence algorithms is quantified using Monte Carlo simulations and compared to the Cramer-Rao lower bound. A computational complexity study shows that our aperture coherence algorithms are suitable for a realtime implementation on an SGI Origin 3000 multi-processor computer.
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Summary

This report develops robust signal processing architectures and algorithms specifically designed to achieve multi-aperture coherence on transmit and receive. A key feature of our approach is the use of orthogonal radar waveforms that allow the monostatic and bistatic target returns to be separated at each receiver's matched filter output. By...

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Wideband aperture coherence processing for next generation radar (NexGen)

Automated tracking for aircraft surveillance radar systems

January 1, 1979
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Conference Paper
Author:
Robert M. O'Donnell
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Published in:
IEEE Trans. Aerosp. Electron. Syst., Vol. AES-15, No. 4, July 1979, pp. 508-517.
Topic:
detection systems
R&D area:
R&D group:

Summary

An improved moving target detector (MTD) (a digital signal processor) has been designed, constructed, and tested which successfully rejects all forms of radar clutter while providing reliable detection of all aircraft within the coverage of the radar. The MTD is being tested on both terminal and enroute surveillance radars for the FAA. This processor has been integrated with automatic tracking algorithms to give complete rejection of ground clutter, heavy precipitation, and angels (birds).
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Summary

An improved moving target detector (MTD) (a digital signal processor) has been designed, constructed, and tested which successfully rejects all forms of radar clutter while providing reliable detection of all aircraft within the coverage of the radar. The MTD is being tested on both terminal and enroute surveillance radars for...

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Automated tracking for aircraft surveillance radar systems

Modes of crossed rectangular waveguide

March 1, 1976
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Journal Article
Author:
Henry J. Stalzer Jr
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Published in:
IEEE Trans. on Antennas Propag., Vol. 24, No. 2, March 1976, pp. 220-223.
Topic:
antennas
R&D area:
R&D group:

Summary

The cutoff frequencies and model fields of dually polarized crossed rectangular waveguide are calculated numerically and the cutoff frequencies verified experimentally. Symmetry arguments and group theory are used to explain mode degeneracies and mode splitting. The single mode bandwidth is 38 percent of center frequency for both polarization when the guide dimensions are chosen appropriately. For applications where symmetric excitation is assured, bandwidths in excess of 2:1 can be obtained.
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Summary

The cutoff frequencies and model fields of dually polarized crossed rectangular waveguide are calculated numerically and the cutoff frequencies verified experimentally. Symmetry arguments and group theory are used to explain mode degeneracies and mode splitting. The single mode bandwidth is 38 percent of center frequency for both polarization when the...

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Modes of crossed rectangular waveguide

Frequency scan antenna design for RPV radar sensors

October 22, 1975
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Project Report
Author:
Francis G. Willwerth
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Published in:
MIT Lincoln Laboratory Report TT-5
Topic:
antennas
R&D area:
R&D group:

Summary

A small program to explore the feasibility of a frequency-scanned antenna as a low-cost, light-weight answer to the requirements of the mini- RPV radar system for the HCWLS program resulted in construction and study of a slotted-waveguide laboratory embodiment of the device. A general formulation of the relationships connecting design parameters was carried out and employed for guidance in selection of waveguide size, band center, and slot spacing. A 301 band from 14.8 to 20.3 GHz in empty WR-42 waveguide was selected. The beamwidth, sidelobe level, gain, attenuation, and efficiency were studied, including the effectiveness of tapered illumination and the occurrence of spurious cross-polarized radiation, as functions of the frequency-controlled scan direction. Some thought was given to alternatives such as aperiodic-array and subarray techniques as means of reducing the tunable bandwidth requirement, as well as stripline serpentine-waveguide designs, for possible future investigation. The work reported herein has shown that the frequency-scanned antenna will provide a low-cost implementation practical for some system applications. If the limitation, primarily in instantaneous signal bandwidth are acceptable in the applications pursued, further investigation of alternate designs is recommended.
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Summary

A small program to explore the feasibility of a frequency-scanned antenna as a low-cost, light-weight answer to the requirements of the mini- RPV radar system for the HCWLS program resulted in construction and study of a slotted-waveguide laboratory embodiment of the device. A general formulation of the relationships connecting design...

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Frequency scan antenna design for RPV radar sensors
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