Analysis for Improving Noise Figures of Countermeasures Receivers
Abstract
Since sensitivity is one of the most important characteristics of a countermeasures receiver, the microwave receivers, TN-139/ULR, TN-140/ULR, TN-141/ULR, and TN-142/ULR, of the AN/SLR-2 (Serial No. 53) were analyzed to determine the lowest noise figure possible and the limitations of the present design. The losses and excess noise characteristics in each of these receivers were analyzed independently to determine the necessary types of modifications for best noise figure. The final innovations consisted of redesigning the r-f input coaxial-line-to-cavity coupler for the TN-139/ULR and TN-140/ULR together with modifying the local-oscillator decoupling circuit in these two receivers and the TN-141/ULR. The design of the mixer incorporated in the TN-141/ULR is inadequate and should be replaced with the type used in the TN-130/APR-9. The investigation of the TN-142/ULR consisted mainly of analyzing the merits of different types of crystals to determine their effect on over-all noise figure. The characteristics of the broadband Sylvania 1N286 coaxial crystal seem sufficiently favorable to warrant a new mixer design to match its r-f impedance.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 15, 1956
- Accession Number
- AD1222157
Entities
People
- N. R. Garofalo
Organizations
- United States Naval Research Laboratory