| EPSRC Reference: |
GR/H39727/01 |
| Title: |
MICROSTRIP ACTIVE ANTENNAS |
| Principal Investigator: |
James, Professor J |
| Other Investigators: |
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| Researcher Co-Investigators: |
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| Project Partners: |
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| Department: |
Electrical Engineering and Science |
| Organisation: |
Cranfield University |
| Scheme: |
Standard Research (Pre-FEC) |
| Starts: |
21 September 1992 |
Ends: |
20 September 1995 |
Value (£): |
71,623
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| EPSRC Research Topic Classifications: |
| RF & Microwave Technology |
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| Panel History: |
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Summary on Grant Application Form |
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To investigate the antenna concept where some active circuits and antenna functions have been integrated in a compatible way. The study will focus antenna developments upon planar microstrip, since this medium is convenient for the mass production of low cost compact printed antennas. The aim of the investigation is to enhance our understanding, and hence design capabilities, of the equivalent circuits and the analysis of radiated fields of such antennas. Further innovation is expected to lead to new antennas which will be of beneficial use.Progress:Professor James took over as the Principle Investigator on 11 March 94 from Dr. P.S. Hall who was appointed to a Chair in the University of Birmingham. Professor Hall is now an Associate Investigator of the project. The change in supervision of the grant has taken place smoothly. To date significant progress has been made in three main areas.(1) The radiation analysis of active devices such as transistors or diodes integrated into arbitrary matched patch antennas has been performed. This has been achieved using a magnetic current model of the active device where port voltages have been determined from the TOUCHSTONE circuit analysis package and combined with a patch cavity model of the microstrip radiator. This flexible analysis approach would be suitable for implementation in an active circuit or antenna radiation CAD tool. A full paper describing the analysis has been published in IEE Proceeding [1]. (2) A phase shifterless microstrip scanned array which utilises injection locked patch oscillators as its principle for phase shifting has been demonstrated and its performance quantified experimentally in terms of scan capability, frequency range and stability. Mutual coupling in this class of array is an important issue which has been examined theoretically using an equivalent nonlinear model of the patch oscillator element and Van Der Pol theory applied to this weakly coupled oscillating system. Phase control using locked oscillator systems is now attracting international attention for applications including mm wave power combination and microwave limited scanned arrays, and it is expected that this work will be of practical relevance to such systems. A paper has been presented at an antenna symposium and a conference paper has been written for submission to the IEEE Proceeding [2]. (3) Finally, ongoing theoretical and developmental work has evolved a new multi-octave circularly polarised microstrip antenna element/array. The antenna element enables higher powers to be radiated through the use of several transistors which are embedded in the transmission line using distributed techniques. This approach enables the gain bandwidth product, of the transistor, to be fully exploited on a curved microstrip line which acts as both transmission line and radiator. The structure is module-like and the line may be configured and/or the modules built up to form a variety of arrays with prescribed characteristics. Additionally the concept provides opportunities for pulse excitation and adaptive control of the antenna characteristics. It is expected that this microstrip antenna will have a wide range of potential uses within sensor and communication systems at microwave and mm wavebands. A conference paper detailing this work has been submitted [3]. [1] Analysis of radiation from active microstrip antennas, Hall P. S., Morrow I. L., IEE Proc.-Microw. Antennas Propag., Vol.141, No.5, Oct 1994. [2] Measurement and modelling of a microwave active patch phased array, Morrow I. L., Hall P. S., James J. R., in preparation for submission to IEEE Proc. Antennas and Propag. [3] Investigation of active wideband printed antennas, Morrow I. L., James J. R., accepted for PIERS conference July 1995.
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Key Findings |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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Potential use in non-academic contexts |
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Impacts |
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| Description |
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk |
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Sectors submitted by the Researcher |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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| Project URL: |
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| Further Information: |
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| Organisation Website: |
http://www.cranfield.ac.uk |