Publications

Refine Results

(Filters Applied) Clear All

Adaptive RF canceller for transmit-receive isolation improvement

Published in:
2014 IEEE Radio and Wireless Symposium (RWS), 19-23 January 2014.

Summary

For effective operation, Simultaneous Transmit and Receive (STAR) systems require high isolation between the transmitted signals and the receiver input, the absence of which can lead to the saturation of a receiver's front end. This paper presents an adaptive RF canceller used to improve isolation. The canceller is configured as an RD tapped delay line with four taps, each with independent amplitude and phase weights that are tuned by a Dithered Linear Search algorithm. This canceller produces 30 dB of signal cancellation over a 20 MHz bandwidth centered at 2.45 GHz in an isolated environment. When combined with a high-isolation antenna, an overall STAR system isolation of 90 dB is achieved, while also maintaining omnidirectional transmit and receive antenna patterns.
READ LESS

Summary

For effective operation, Simultaneous Transmit and Receive (STAR) systems require high isolation between the transmitted signals and the receiver input, the absence of which can lead to the saturation of a receiver's front end. This paper presents an adaptive RF canceller used to improve isolation. The canceller is configured as...

READ MORE

Transactional array reconciliation tomography for precision indoor location

Published in:
IEEE T. Aero. Elec. Sys. Vol. 50, No. 1 January 2014, pp. 17-32.

Summary

A novel system is described for precision indoor location and tracking of personnel inside a building using RF signals exchanged with reference units deployed outside the building without benefit of infrastructure or site survey. Localization in high multipath without multilateration by fusion of unidirectional signals using singular array reconciliation tomography is reviewed. The bidirectional signal fusion approach is introduced with transactional array reconciliation tomography. Underlying theory is developed, and performance evaluated with simulated and experimental data.
READ LESS

Summary

A novel system is described for precision indoor location and tracking of personnel inside a building using RF signals exchanged with reference units deployed outside the building without benefit of infrastructure or site survey. Localization in high multipath without multilateration by fusion of unidirectional signals using singular array reconciliation tomography...

READ MORE

Ultrawideband superstrate-enhanced substrate-loaded array with integrated feed

Published in:
IEEE Trans. Antennas Propag., Vol. 61, No. 11, November 2013, pp. 5802-7.
Topic:
R&D group:

Summary

A superstrate-enhanced substrate-loaded array (SESLA) with an integrated feed is presented. The design allows for a practical implementation of the SESLA, a concept previously presented by the authors for realizing extremely wideband (> 10 : 1) low-profile arrays. Specifically, the feed provides unbalanced to balanced transformation allowing the balance-fed SESLA to be excited with a 50 omega unbalanced line. The resulting array/feed combination is matched across a 13.9 : 1 bandwidth (infinite array, V SW R less than or equal to 2.4). When scanned to 45 degrees in the E-, H-, and D-planes, the unit cell operates across a 13.3 : 1 bandwidth using a relaxed matching criterion of V SW R less than or equal to 3. The design is validated through extensive measurement of an 8x8 prototype array.
READ LESS

Summary

A superstrate-enhanced substrate-loaded array (SESLA) with an integrated feed is presented. The design allows for a practical implementation of the SESLA, a concept previously presented by the authors for realizing extremely wideband (> 10 : 1) low-profile arrays. Specifically, the feed provides unbalanced to balanced transformation allowing the balance-fed SESLA...

READ MORE

Multi-lithic phased array architecture for airborne sense and avoid radar

Summary

Transmit and receive Ku-band phased array designs are described for testing an airborne sense and avoid radar. The arrays are small with a size of 24 cm x 9 cm and operate from 13 to 17 GHz with electronic scanning from plus of minus 45 degrees in azimuth and plus of minus 30 degrees in elevation. A novel design architecture allows the use of multiple multilayered printed circuit boards and simple air cooling.
READ LESS

Summary

Transmit and receive Ku-band phased array designs are described for testing an airborne sense and avoid radar. The arrays are small with a size of 24 cm x 9 cm and operate from 13 to 17 GHz with electronic scanning from plus of minus 45 degrees in azimuth and plus...

READ MORE

Ultrawideband time-delay steered UHF dipole linear array antenna

Published in:
2013 IEEE Int. Symp. On Phased Array Systems and Technology, 15-18 October 2013.

Summary

An ultrawideband fixed time-delay steered UHF dipole array antenna has been developed for coverage in the 300 to 450 MHz frequency range for communications or radar applications. The antenna utilizes a parasitically-tuned dipole array for linear polarization and is mounted over a ground plane. Numerical electromagnetic simulations were used to analyze and optimize the antenna parameters prior to fabrication. Measurements of the prototype antenna in an anechoic chamber demonstrate the antenna's reflection coefficient and radiation gain pattern performance.
READ LESS

Summary

An ultrawideband fixed time-delay steered UHF dipole array antenna has been developed for coverage in the 300 to 450 MHz frequency range for communications or radar applications. The antenna utilizes a parasitically-tuned dipole array for linear polarization and is mounted over a ground plane. Numerical electromagnetic simulations were used to...

READ MORE

Ultrawideband cavity-backed resistively loaded planar dipole array for ground penetrating radar

Published in:
2013 IEEE Int. Symp. On Phased Array Systems and Technology, 15-18 October 2013.

Summary

An ultrawideband (UWB) cavity-backed resistively loaded planar dipole array antenna has been developed for the 100 to 400 MHz frequency range for ground penetrating radar applications. The antenna has been designed with a 3m aperture to perform surveys of a wide swath of ground from a moving vehicle. The performance of the UWB array is quantified by moment method simulations of the electromagnetic field penetration into lossy soil. Integration of the UWB array onto vehicle is discussed.
READ LESS

Summary

An ultrawideband (UWB) cavity-backed resistively loaded planar dipole array antenna has been developed for the 100 to 400 MHz frequency range for ground penetrating radar applications. The antenna has been designed with a 3m aperture to perform surveys of a wide swath of ground from a moving vehicle. The performance...

READ MORE

Stepped notch antenna array used as a low thermal resistance heat sink

Summary

A stepped notch antenna at Ku-band is developed to provide a thermal heat sink for active arrays. The antenna with forced air cooling provides up to 0.4 degrees C/W of thermal resistance. The antenna integration with a printed circuit board allows for high volume surface mount assembly of active devices.
READ LESS

Summary

A stepped notch antenna at Ku-band is developed to provide a thermal heat sink for active arrays. The antenna with forced air cooling provides up to 0.4 degrees C/W of thermal resistance. The antenna integration with a printed circuit board allows for high volume surface mount assembly of active devices.

READ MORE

The directivity of a Yagi-Uda antenna from an effective propagation constant

Published in:
IEEE Int. Symp. Antennas and Propagation (APSURSI), 7-13 July 2013.

Summary

A technique is presented for determining the directivity of a long, uniform Yagi-Uda antenna. It is shown that the maximum directivity is limited by the propagation constant of the particular antenna structure. The propagation constant can be determined by means of a two-part antenna test fixture with M and M + 1 directors.
READ LESS

Summary

A technique is presented for determining the directivity of a long, uniform Yagi-Uda antenna. It is shown that the maximum directivity is limited by the propagation constant of the particular antenna structure. The propagation constant can be determined by means of a two-part antenna test fixture with M and M...

READ MORE

Ring array antenna with optimized beamformer for simultaneous transmit and receive

Published in:
2012 IEEE Antennas and Propagation Society International Symp. and USNC/URSI National Radio Sci. Mtg., 8-14 July 2012.

Summary

In order to avoid self-interference, Simultaneous Transmit And Receive (STAR) systems require low mutual coupling between their respective transmit and receive antennas. This paper discusses the development of an 8-element transmit ring array antenna on a circular ground plane with a raised receive element. When combined with a beamformer that supplies linear progressive phase shifts to the array with opposing elements phased 180-degrees apart, the receive and transmit antennas are measured to exhibit 55 dB of isolation and omni-directional patterns in the 2.4 to 2.5 GHz band.
READ LESS

Summary

In order to avoid self-interference, Simultaneous Transmit And Receive (STAR) systems require low mutual coupling between their respective transmit and receive antennas. This paper discusses the development of an 8-element transmit ring array antenna on a circular ground plane with a raised receive element. When combined with a beamformer that...

READ MORE

Maximum directivity of a series-fed microstrip array antenna for wireless application

Published in:
AP-S/URSI 2011, IEEE Antennas and Propagation Society Int. Symp. and USNC/URSI National Radio Science Mtg., 3-8 July 2011, pp. 1327-1330.

Summary

An omnidirectional colinear microstrip array antenna is modeled as a ladder network. A formula is derived for the maximum directivity of a series-fed colinear antenna with an infinite number of ladder sections. It is shown that the maximum directivity is asymptotically limited and depends upon the product of the seriece impedance and shunt admittance of the equivalent ladder network. The result is verified by simulation and experiment.
READ LESS

Summary

An omnidirectional colinear microstrip array antenna is modeled as a ladder network. A formula is derived for the maximum directivity of a series-fed colinear antenna with an infinite number of ladder sections. It is shown that the maximum directivity is asymptotically limited and depends upon the product of the seriece...

READ MORE