Wave transmission lines and networks – Long lines – Strip type
Patent
1996-08-01
1998-03-03
Gensler, Paul
Wave transmission lines and networks
Long lines
Strip type
333244, H01P 308
Patent
active
057240124
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a transmission-line network, comprising an assembly of a first conductive base, a first dielectric sheet having a constant thickness, a second dielectric sheet having a constant thickness, a second conductive base, and a stripline network, located between the first dielectric sheet and the second dielectric sheet. Such transmission-line networks are for instance used as distribution networks in phased array or multibeam antennas. A drawback of these well-known transmission-line networks is their relatively limited capability for power transmission owing to heat developing in the dielectric sheets near the inner conductor structure as a result of dielectric losses, which could cause excessive heating of the transmission-line network.
DISCUSSION OF THE BACKGROUND
An improved transmission-line structure is known from GB-A 2.217.114, where the stripline network is located in a groove in one dielectric sheet, such that one side of the stripline network is free of dielectric. For high power applications this known transmission-line structure has as a disadvantage that one side of the stripline network still contains dielectric, which may give rise to overheating, especially as the electromagnetic fields tend to concentrate on the side containing dielectric.
For a distribution network the known transmission-line structure has moreover as a disadvantage that the stripline network is not symmetric in the sense that the speed for electromagnetic waves is different for the side with the dielectric, compared with the side without dielectric. This implies that the phase lengths of stripline parts are not well-defined, which is unacceptable in a distribution network.
SUMMARY OF THE INVENTION
The present invention has for its object to realize a transmission-line network that does not experience these drawbacks and is characterized in that for at least part of the stripline network both dielectric sheets are provided with a cavity whose form conforms at least substantially to that part of the stripline network, such that for that part the transmission line network contains at least substantially no dielectric.
For supporting the stripline network, a first favourable embodiment is characterized in that the width of the cavity has at least locally been selected for being smaller than the width of the stripline network. Thus, the volume of dielectric that will cause the occurrence of dielectric losses will be strongly reduced, any remaining dielectric only being present on the edge of the inner conductor structure where the occurring electric field strengths and, consequently, the occurring dielectric losses will usually be smaller. Moreover, it will generally not be required to support the inner conductor structure over its entire length as a result of which, in those regions where support is desired, the presence of a limited volume of dielectric between the inner conductor structure and the first and the second conductive base, may suffice.
In a second exceptionally favourable embodiment the stripline network can be placed on a dielectric film, which is placed between the first and the second dielectric sheet. It will then be possible to select the width of the cavity to be larger than the width of the stripline, resulting in the complete elimination of dielectric losses occurring in the dielectric sheet.
This entails the additional advantage that the stripline network can be implemented as a printed circuit placed on the dielectric film. It furthermore enables complex inner conductor structures to be manufactured at relatively low cost.
Transmission-line networks thus obtained are capable of high-power transmission, the ohmic losses in the inner conductor structure and dielectric losses occurring in the dielectric film constituting the restrictive factors. By for instance using KAPTON or polyamide, these dielectric losses can be kept low.
An additional advantage of the invention is that the power to be transmitted can be further increased by cooling the inner conduc
REFERENCES:
patent: 2800634 (1957-07-01), Grieg et al.
patent: 3768048 (1973-10-01), Jones, Jr. et al.
Schneider, Microstrip Lines for Microwave Integrated Circuits, The Bell System Technical Journal, vol. 48, No. 5, May-Jun. 1969, pp. 1421-1424.
Gensler Paul
Hollandse Signaalapparaten B.V.
LandOfFree
Transmission-line network does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Transmission-line network, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Transmission-line network will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2252244