| Autor: |
Thomas Swanson |
| Rok vydání: |
1979 |
| Předmět: |
|
| DOI: |
10.21236/ada075286 |
| Popis: |
This report describes design and construction of a prototype improved electronically tunable UHF receiver preselector for interference reduction in Air Force communication systems. This research work was directed toward developing the technology for frequency agile preselectors to protect solid state receivers from high level signals originating from colocated UHF transmitters. The design approach consists of tuning a modified comb-line filter structure with high Q UHF capacitors and pin diode switches. Equations and design considerations are given for construction of tuning networks which have Cx2 to the Nth power binary capacitance steps. A computer program was used to predict the filters performance based on the values of stray capacitance and inductance of the tuning networks. The tuning networks were then optimized which ensured that spurious resonances fell well outside of the tuning range of the filters. The filters were built based on these computer modeled results. Test data showed input VSWR variation versus the tuning frequency of the filters. These changes were found to be caused by variation in current loading at the tap point of the resonator resulting from the different values of capacitance selected in the tuning network. Improved filter performance was obtained by grounding the input transformers in the vicinity of the tuning network tap point. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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