Wave transmission lines and networks – Plural channel systems – Having branched circuits
Reexamination Certificate
1999-01-06
2001-06-26
Gensler, Paul (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Having branched circuits
C200S504000, C333S108000, C335S005000
Reexamination Certificate
active
06252473
ABSTRACT:
TECHNICAL FIELD
The present invention relates to microwave switches, and more particularly to three-dimensional (3D) microwave switches, specifically octahedral-shaped switches, for routing microwave signals along selectable signal paths among a plurality of switch ports.
BACKGROUND ART
Microwave switches are used in redundant switching networks on spacecrafts to route M input signals to M outputs through N failure-prone devices, such as traveling wave tube amplifiers (TWTAS). This is accomplished using two layers of microwave switches, with each layer including M serial connected 4-port switches, for example, T-switches. The switches in the input layer are controlled to route the M input signals around the failed devices and through functioning devices. The switches in the output layer are controlled to route the signals produced by the M selected devices to the M outputs.
Typically, planar T-switch configurations are used effectively in redundant switching networks on board spacecraft. However, there are a number of drawbacks associated with the prior art switches. A typical spacecraft employs several hundred microwave switches so that a small reduction in the weight of each switch can result in significant cost savings.
The actuators are the primary weight components of the switches, and therefore a switch configuration having a simpler and lighter weight actuator is desirable. Further in a planar T-switch, the three inner and outer waveguides necessarily have different lengths. As a result, the signal paths through different ports have different microwave properties, which prohibits the overall system from being optimized. In addition, the ends of the center conductors are flared substantially to ensure contact to the underlying conductive reeds in the actuators. This limits the high frequency performance of the switch. Also in a planar T-switch, the physical access to the coaxial connector is limited. Finally, as the complexity of the redundant switching networks increases, it may be difficult to develop planar microwave switches with enough ports to reroute the signals.
The prior art encompasses a dual T-switch assembly that consists of two T-switches with a coaxial cable running between them. When connected together, a signal going into one switch can be passed through intermediate switches to any output. To accomplish this the assembly requires twelve signal paths, eight connectors and a coax cable. This configuration adds unnecessary weight and complexity to the switch assembly. The complexity of the system also results in diminished RF performance.
Pat. No. 5,936,482 provides a lighter weight three dimensional microwave switch that has improved uniformity between signal paths, high frequency performance and physical access. The switch configures the waveguide transmission lines in three dimensions to define a polyhedron and positions the I/O microwave ports at the corners of the polyhedron. An actuator selectively moves respective reeds in the waveguide transmission lines between a signal-attenuating position abutting the interior surface of the waveguide transmission line and a signal-conducting position substantially coaxial with the waveguide transmission line and abutting the signal lines of the I/O microwave ports coupled to opposite ends of the waveguide transmission line.
The three dimensional switch may have an octahedral cavity providing six (6) connectors and twelve (12) paths. Although the octahedral configuration requires an independent actuator for each path, it retains the microwave performance advantages of identical path lengths and configuration while reducing weight and simplifying the microwave path.
The three-dimensional switch proposed in Pat. No. 5,936,482 is lighter in weight and more reliable in performance than prior art microwave planar switches. However, it still has a complex interconnection arrangement that requires coax cables to connect switches. In addition, the three-dimensional switch has somewhat limited signal path flexibility.
There is an ever present need for reduced weight in spacecraft applications and improved RF performance. There is also a need for simplified switch interconnection methods and increased signal path flexibility over the prior art.
SUMMARY OF THE INVENTION
The present invention provides a three-dimensional microwave switch for routing signals in an operating frequency band along selectable signal paths, and particularly for routing signals around failed devices in redundant switching networks on board spacecraft. The microwave switch of the present invention is particularly useful for interconnecting switches. It has reduced weight, simplified interconnection requirements, improved RF performance and improved signal path flexibility in comparison to prior art switch assemblies.
The RF microwave coaxial switching device of the present invention is based on the three dimensional octahedral switch disclosed in Pat. No. 5,936,482, the disclosure of which is hereby incorporated by reference herein. That switch has six connectors and twelve transmission lines. In contrast, the three-dimensional switch of the present invention has six connectors and thirteen transmission lines arranged in an octahedral shape. The thirteenth transmission line is a through path between two opposing connectors and passes through the interior of the switch cavity. This additional transmission line allows one three dimensional switch of the present invention to replace two switches that are required in prior art dual T-switch assemblies.
The switch of the present invention encompasses all usable prior art dual T-switch states and has several additional states that are not obtainable with the prior art dual T-switch arrangement. Typically, the transmission lines and ports are formed as part of a one-piece conducting cavity, but they may also be connected in a skeletal configuration.
The three-dimensional microwave switch topology facilitates the use of simpler actuating mechanisms than are used in planar microwave switches, making them lighter weight than their planar counterparts. In addition, the conductive reeds contact the port's signal line around its circumference rather than at its end, thereby allowing the signal line to have less flare and better high frequency performance. The physical access to the switch is also improved by locating the connectors at the corners of the three-dimensional shape of the switch. The three-dimensional topology incorporates an octahedral-shaped cavity for the switch. The switch also has six ports, which are useful in more complex redundant switching networks.
It is an object of the present invention to reduce the weight of redundant microwave switches.
It is another object of the present invention to improve the RF performance of redundant microwave switches.
It is yet another object of the present invention to improve performance over prior art dual T-switch assemblies, while reducing the number of intermediate paths a signal must pass through.
It is still another object of the present invention to increase signal path flexibility.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.
REFERENCES:
patent: 3260967 (1966-07-01), McClaflin et al.
patent: 3270299 (1966-08-01), Stapf
patent: 4070637 (1978-01-01), Assal et al.
patent: 5724014 (1998-03-01), Leikus et al.
patent: 5936482 (1999-08-01), Ando et al.
Gensler Paul
Gudmestad T.
Hughes Electronics Corporation
LandOfFree
Polyhedral-shaped redundant coaxial switch does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polyhedral-shaped redundant coaxial switch, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polyhedral-shaped redundant coaxial switch will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2479067