Down conversion and filtering of microwave signals in optical domain

Selçuk, Gökhun
Processing of microwave signals in electrical domain introduces many difficulties especially when the frequency of the signal is increased beyond several GHz. Electromagnetic interference (EMI) and frequency depended losses can be given as examples to these difficulties. Photonic processing of microwave signals, however, is immune to these problems since optical components such as fiber cables, lasers, optical modulators and photodetectors are both immune to EMI and have wide bandwidths. This thesis deals with down conversion of a microwave signal using a Mach-Zender modulator and filtering unwanted harmonics using a photonic filter.


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n this thesis, RF sections of a multi tier instantaneous frequency measurement (IFM) receiver which can operate in 2 – 18 GHz frequency band is designed, simulated and partially realized. The designed structure uses one coarse tier, three medium tiers and one fine tier for frequency discrimination. A novel reflective phase shifting technique is developed which enables the design of very wideband phase shifters using stepped cascaded transmission lines. Compared to the classical phase shifters using coupled ...
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It is well understood that the maximum likelihood estimator is a powerful equalisation technique for frequency selective fading channels, and in particular for MIMO systems. The complexity of this estimator, however, grows exponentially with the number of users and multipath taps, hence limiting the use of this algorithm in MIMO systems. In the paper, the authors propose a joint spatial and temporal channel-shortening filter as a pre-processor to reduce significantly the complexity of a maximum likelihood e...
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Unlu, M.; Demir, Şimşek; Akın, Tayfun (Institution of Engineering and Technology (IET), 2012-10-23)
This study shows that the well-known triple stub circuit topology can also be used for controlling the insertion phase and amplitude of a given signal simultaneously, as well as preserving its impedance transformation ability. The triple stub circuit topology, which is nothing but an extension of the conventional double stub loaded-line phase shifter, results in one more degree of freedom to its solution when it is solved for its insertion phase. This additional degree of freedom not only brings the impedan...
Citation Formats
G. Selçuk, “Down conversion and filtering of microwave signals in optical domain,” M.S. - Master of Science, Middle East Technical University, 2008.