Researchers at the Institute of Electronics, Communications and Information Technology (ECIT) and the Northern Ireland Semiconductor Research Centre (NISRC) at Queen's University Belfast have devised a way to eliminate the need for motors in space borne radiometers by incorporating liquid crystals in their Frequency Selective Surface (FSS) antenna arrays.
The project has attracted funding of £0.5 million from the European Space Agency (ESA) and £100,000 from economic development agency, Invest Northern Ireland. It is expected to result in significant weight savings in satellite payloads and greatly reduced power consumption in weather monitoring instruments.
The technology has other important potential applications as well. These include eradicating the attenuation of mobile phone signals passing through energy efficient glass and creating buildings that can be locked down to block radio signals at the flick of a switch.
The innovative ECIT project addresses frequencies ranging from millimeter wave up to 1 THz. Measuring radiation in this waveband is a key technique used to study the earth’s atmosphere to improve global weather forecasting and understanding of climate change.
Current generation remote sensing radiometers that collect this data incorporate a turntable-mounted mirror operated by an electric motor to calibrate the instrument before each scan by directing their field of view between cold and ambient targets.
The ECIT/NISRC research team however has devised a technique for making such motors redundant. This involves sandwiching layers of liquid crystals between the FSS’s metalized quartz layers to act as an electronically controlled shutter. Applying a small voltage to the structure then enables the radiometer to be switched from calibration mode to signal detection mode without mechanical components.
The team believes that using this technique to replace the motor and turntable could produce potential weight savings of 10 per cent per radiometer. It would also greatly reduce power consumption requirements as a motor represents a radiometer’s single biggest power requirement.
Prototypes are being built at Queen’s University’s Northern Ireland Semiconductor Research Centre with ESA support and the devices are expected to be used in space missions from 2025 onwards.