Coaxial switching system with switched shields and crosstalk suppression
US4766401A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 30, 1987 |
| Grant date | Aug 23, 1988 |
| Priority date | — |
| Expiry date | Jul 30, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B3/32
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A switching network for coaxial transmission lines switches both the center conductors and the shields to allow floating measurements and eliminate the effects of ground loops. The shields are switched even though the coaxial relays used to switch the center conductors do not themselves also switch the shields. This is accomplished by using two coaxial relays having connected center conductors, each of which coaxial relay is itself shielded, and a third relay to selectively connect and disconnect the shields of the coaxial relays. All three relays open and close in unison. Although this arrangement provides excellent isolation when open within the circuit where it is used, there is unfortunately a coupling mechanism between pairs of such circuits having such relay arrangements that are closed. This coupling mechanism produces crosstalk between such pairs of circuits. The crosstalk current tends to flow in a resonant circuit. Both the resonant peak of the crosstalk current and its non resonant magnitude can be reduced by the inclusion of magnetic cores (such as lossy ferrites) around the coaxial transmission lines as they enter and leave the coaxial relays.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.