Compact, low-intermodulation multiplexer employing interdigital filters
US5446729A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 1, 1993 |
| Grant date | Aug 29, 1995 |
| Priority date | — |
| Expiry date | Nov 1, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04J1/08
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An improved multiplexer comprises a housing, a transmission line transformer section within the housing extending in a first direction, and at least two interdigital transmission line filters adjacently disposed within the housing along the first direction. The transformer section has a first end electrically coupled to an antenna circuit connector, and a second end electrically coupled to the housing (i.e. grounded). Each filter includes several resonating elements. At least one resonating element of each filter is located in proximity with a portion of the transformer such that electrical coupling between the filter and the transformer is established. The length of each coupling portion of the transformer is approximately one-quarter electrical wavelength at the center frequency of the associated filter. The dimensions of the filter cavities are preferably selected to be as small as possible without unacceptably degrading the filter insertion loss. Further, the filters, and the associated coupling portions of the transformer, are disposed in close proximity. The filter cavity size and spacing are such that the transformer coupling portions of adjacent filters are no more than abo…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.