Radar receiver pdf

Image-rejection Mixer 5. Uses a single diode that terminates a transmission line, LO is inserted via a directional coupler. The unwanted Image frequency is short circuited or Open circuited. Diode being a non-linear device produces inter- modulation products, called Spurious responses. Taylor proposed a mixer chart to determine the RF and LO frequencies that are free from spurious responses. A Mixer chart is a graphical representation of wanted and unwanted spurious mixing products in-band and out-of-band.

Presence of two or more RF signals also results in spurious responses. Single conversion receivers suppress these spurious responses. In some cases the RF and LO signals are subjected to a Diplexer in order to provide proper isolation between them. Two single ended mixer in parallel and o out of phase. A 4-port junction such as magic-T, hybrid junction or 3dB coupler is used. LO and RF signals are applied at ports 1 and 2, their sum and difference is obtained at ports 3 and 4. Perks: LO noise at the two diode mixers are in phase and gets cancelled out Suppresses the even harmonics of either LO signal or the RF signals.

Permits wide bandwidth. Suppresses even harmonics of both LO and RF ports. Drawbacks: High LO drive required. Increased cost and complexity. The RF signal is split into two and fed into two individual mixers. LO signal is split into two using a 90o Hybrid junction. A second hybrid junction IF imparts another 90o phase shift to separate the image frequency. The port with the image frequency is match terminated.

RF IF. Low Inter-modulation Products. Less susceptibility to Burn out. Drawback: Provides only 30dB image rejection, which may not be suitable for some applications. High noise figure. Dynamic Range of a radar receiver is the Ratio of max input signal power to minimum input signal power without degradation in performance.

Third order modulation product affects the dynamic range of radar. Mixer conversion loss is reduced by terminating a diode in a reactance at the image frequency. The improvement using this image enhancement is as low as 1 or 2 dB.

Band pass filtering around the input source prevents the image frequency from entering into the mixer again. Open navigation menu. Close suggestions Search Search. User Settings. Skip carousel. Carousel Previous. Carousel Next. What is Scribd? Explore Ebooks. Bestsellers Editors' Picks All Ebooks.

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Did you find this document useful? Share This Paper. Background Citations. Methods Citations. Results Citations. Figures, Tables, and Topics from this paper. Citation Type. Has PDF. Publication Type. More Filters. A spectrum sharing scheme is considered in which ship-based radar stations are operating in the same spectrum band as on-shore communication transmitters, and in which the communication transmitters … Expand.

Effects of a near-field radio frequency interference on a marine navigational X-band radar. This paper discusses the effects of different types of radio frequency interferences on the radar receiver of a navigational X-band radar as displayed on the plan position indicator PPI.

In … Expand. Highly Influenced. View 8 excerpts, cites background and methods. View 10 excerpts, cites results, methods and background. Impact on radar probability of detection due to interference from 4G communication signals.

View 2 excerpts, cites background. Characterizing an S-band marine radar receiver in the presence of interference. Characterizing the effects that out-of-band interference has on the performance of an S-band marine radar receiver's IF output normally requires non-linear network analysis. We have developed a … Expand. View 1 excerpt, cites background. Spectrum reallocations may place broadband radio services BRS near spectrum used by — MHz band marine radars.

Signals from the BRS base stations can potentially introduce unwanted emissions … Expand. View 3 excerpts, cites background and results. Doppler weather radar. Proceedings of the IEEE.