PHASED ARRAY TECHNOLOGIES

SUMMARY

Phased array antenna technology covers a very broad field and there is already extensive research and development work in hand in the UK. The DTC aims to examine more advanced concepts in later years, but initially work will be focus on some specific aspects of the subject.

The first area within this sub-theme consists of research into a number of similar topics, all aimed at exploiting novel technologies to realise robust, high performance, low cost RF devices. These devices can form the fundamental building blocks for cheap, effective RF sensor systems. The main thrust of this work is concentrated on MEMS (Micro Electro-Mechanical Systems).

This is complemented by research into a novel approach to phased array calibration which, if successful, could considerably simply this aspect of phased array design with consequent cost benefits.

It should also be noted that much of the work proposed within the Transduction Devices and Materials Research Theme addresses the issues of manufacturability of phased array components.

MILITARY BENEFITS

Active array radars offer many well-documented military advantages, but costs remain a concern. Analogue RF devices and array calibration, using conventional techniques, are significant contributors to the overall cost of the system. This research offers the possibility of significant cost savings without loss of performance.

RESEARCH OBJECTIVE

To demonstrate the feasibility of electromagnetically actuated MEMS
To demonstrate the integration of passive and active devices in multilayer Monolithic Microwave Integrated Circuit (MMIC) structures
To develop phased array calibration procedures based on the use of a far-field reference source, either co-operative or non-co-operative (targets of opportunity)

RESEARCH OUTLINE

MEMS- Prior work has developed techniques to incorporate ferromagnetic material in MEMS structures, which provides the magnetic material for an electromagnetic actuator. Calculations have shown that this can provide much greater actuation forces than electrostatic methods, and this is expected to provide better contact forces for good electrical performance and long term reliable operation. This project aims to demonstrate very low-loss, high performance RF switches based on these principles.

Multilayer MMICs- At high RF frequencies it is essential to employ a large amount of passive circuitry for functions such as matching, biasing, phase shifting, coupling and filtering. As a result the passive components on MMICs often take up far more space than the active devices such as MESFETs, HEMTs and HBTs. Multilayer techniques have been shown to be a viable method for miniaturising the passive components. Miniaturised inductors or transmission lines with size reductions of one-third to one-quarter can be obtained by this technology. The research aims to demonstrate and characterise novel passive circuits using multilayer circuits.

Calibration- This research will examine the possibility of using point targets of opportunity as part of the calibration methodology. Auto-focus algorithms will be assessed for suitability. Additional techniques from the fields of adaptive beam-forming and superresolution will be considered in the case where the characteristics of the antenna elements are not exactly known. The cost-effectiveness (and logistical practicality) of providing some limited external calibration signals and extra calibration paths to aid the autonomous system will also be considered. The research is potentially applicable to air, ground and sea-based systems.

CO-ORDINATION WITH EXISTING / PREVIOUS RESEARCH

The MEMS and MMIC work is based on prior work by the researchers. The applications being considered are novel. The calibration work is primarily of a novel nature, but is based on the Consortium members’ experience of phased array systems.

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