Development of Low Loss Multipole RF Filters.
Abstract
In the second year, the research work has been carried out in two directions: improving the old filter structure based on interdigital capacitor design and developing a new structure. Some modifications were made to the interdigital capacitor design and fabrications. The testing results showed some improvement on the device performance. However, these filters are too sensitive to matching capacitors, which are very small in capacitance. These matching capacitors can not be increased to achieve the purpose. New HTS three-pole bandpass filters of 24 MHz have been designed, fabricated, and tested using a spiral resonator structure. Three signal input/output coupling loops were used in the measurement of the filters: big-loop, small-loop-near, and small-loop-far. The best result so far is obtained from small-loop-far coupling which gives the three-pole center frequency of 24 MHz, an insertion loss of -2 dB, a return loss of -5 dB, and a stopband of <-40 dB. The project has made progress with the new design in decreasing insertion loss, increasing return loss and increasing stability and repeatability in fabrication. The new design is more flexible in terms of matching and adjustment of bandwidth or frequency. Based on the new filter results, a patent application has been filed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 30, 1998
- Accession Number
- ADA350284
Entities
People
- Q. Y. Ma
Organizations
- Columbia University