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Recent Advances in Radar Technology
Using Calibration to Optimize Performance in Crucial Measurements
Right from its inception European Microwave Week has involved radar activities; with the number of radar related papers increasing year-by-year until in Amsterdam in October 2004, the current series of separate conferences began. That growth has continued with the 2006 European Radar Conference seeing a substantial conference programme consisting of 55 papers for oral presentation and 35 poster papers. The poster session will be presented in the European Microwave Exhibition Hall on Thursday 14 September.
Such participation demonstrates a thriving European radar community. It is also an indicator of activity geographically, so it is worth noting the significant representation from the Newly Independent States, most notably Ukraine, alongside the established West European countries.
The papers cover a very wide range of topics. Among them are presentations on sparse antenna arrays, remote sensing of the atmosphere, ultra wideband radar, real-time signal processing, novel antennas, SAR, new transmitter techniques, millimetre-wave radar and netted radars. Also included are workshops on radio astronomy techniques with a visit to Jodrell bank and a workshop on microwave sensors and imaging systems.
Patrick Beasley identifies current trends and future developments
The most significant recent trend in radar development has been the convergence between radar and communications techniques and technologies. This has been driven by the ability to design low power, solid state, CW-type radars taking advantage of low cost microwave components, up to I-band and beyond, together with the availability of high throughput, low cost signal processing capabilities, including optical signal processing which facilitate digital beamforming and space-time processing.
Radars are being developed that exploit communications techniques including MIMO transceivers, OFDM and ultra wideband. In particular, the improvement in ADC sampling speeds and increase in the number of bits has moved the digitisation stage closer to the radar front end where dynamic range requirements are more demanding. Additionally, Direct Digital Synthesis (DDS) has provided a means to create waveforms of choice and facilitates coherent radar operation with the corresponding benefits of improved detection, simultaneous range/Doppler processing and clutter rejection.
There has also been a significant improvement in microwave and millimetre-wave oscillator sources in terms of ultra low phase noise and improved frequency stability, which, again, facilitates coherent radar operation. Phase-locked DROs and low cost VCOs developed for communications applications are replacing traditional sources and there is a demand for increased radar bandwidth for improved range resolution, particularly for surveillance radars, and for low peak transmit powers. This highlights the importance of spectrum sharing and the use of ‘orthogonal’ waveforms to prevent interference.
Developments in millimetre-wave radar have accelerated in recent years with the availability of relatively low cost components developed for automotive radar and point-to-point communications and a rapid increase in demand for passive millimetre-wave imaging for security applications. These radars are finding niche applications such as runway debris monitoring, radar level sensing, high resolution imaging and robotics.
The concern about the environment has lead to significant research into radar remote sensing of the atmosphere from space, airborne and land-based platforms. This provides meteorological and hydrological information and the information can also be used to assist in aviation safety. Advances in polarimetric SAR are key to achieving this aim and there are significant research efforts currently being carried out in France, The Netherlands and Ukraine.
In the field of radar antennas the most exciting research is being carried out into conformal antennas, the use of metamaterials and plasma antennas. There is significant development into sparse antenna arrays which share common techniques with the radio astronomy community.
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