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Microwaves and Antenna Engineering Research Group

Pioneering the analysis, design and integration of high frequency electronics devices and systems

Research staff: Prof Jason Hong and Dr Jai Ni

External collaborator: European Space Agency (ESA/1-7747-13-NL-GLC))

Funding body and estimated budget: ESA - Euro 250,000

Duration: 2014-17

Project descriiption: Often, significant filtering requirements exist for planar and drop-in receiver filters at IF frequencies in the 1 to 4 GHz frequency range of typically 3 to 7x fIF (centre frequency) to comply with spurious emission requirements and suppression of spurious outputs. Filter requirements become even more challenging when a number of up- or down-converter stages are cascaded in advanced payloads where specifications for up to 10x fIF arise. Today, to achieve such very demanding requirements several low- and high-pass filters have to be cascaded in order to provide the in-band and out-of-band required performances (alternative solutions are based on a bandpass clean-up filter and a low pass filter). Apart from high design, manufacturing and tuning complexity, this leads to a significant filter real estate which is not acceptable. Due to the position of the IF filters in the RF chain, absolute insertion losses can be easily compensate by means of the power amplification stages located before and after the filter. However, sharp rejection and flat pass band insertion loss are required which lead to high-Q resonators. Lossy and predistorted design theory for filters can provide the requiredrejection and flatness avoiding the use of high-Q materials, which are more expensive, and allowing the required compactness. The side effects will be the deterioration in absolute insertion and return losses for input and output. The objective of this activity is the development and demonstration of compact IF filters with ultra-wide stopband.