Varactor-Tuned Helical Resonators at UHF,
Abstract
A JTIDS requirement calls for narrowing the front-end bandwidth of fast-tuning L-band receivers in order to improve their interference resistance. Filters suitable for this application have to be of high Q and compact design. Frequency tuning or switching within microseconds is required. The performance of optimally designed halfwave helical resonators is investigated with microwave varactors of Q greater than 4000 and Q greater than 10000 (at 50 MHz and 4V reverse bias) as tuning elements. Four filters were designed to cover sections of a frequency range 294 MHz to 1256 MHz. At the low end of this range the varactor Q is comparable to or better than that obtained from helical resonators of 1-in. shield diameter. At the high end of this range the varactor Q is such that there is a substantial degradation of overall resonator Q at maximum varactor capacitance (at 1V reverse bias). The compatibility of varactor-tuned helical filters with requirements of the JTIDS receivers is evaluated. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1976
- Accession Number
- ADA031421
Entities
People
- Martin R. Stiglitz
- Uve H. W. Lammers
Organizations
- Rome Laboratory