Vacuum Microwave Transmission Line Geometry to Avoid Multipaction
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Solution Overview
Problem
Existing transmission lines in vacuum environments for satellite antennas and beamforming networks face issues with multipaction, which is exacerbated by increased power, leading to unwanted discharges and requiring larger, bulkier designs to maintain impedance.
Innovation Solution
The transmission line design incorporates a conductor strip with strategically positioned portions closer to the ground plane, creating fringing electromagnetic fields that redirect excited electrons parallel to the ground plane, thereby avoiding multipaction while maintaining impedance without increasing volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between the conductor strip and the ground planes is increased to avoid multipaction, then multipaction is reduced, but the transmission line becomes bulkier and more expensive
Solution Approach 1:
The conductor strip is designed with varying distance from the ground plane at different locations. The edges are positioned closer to the ground plane while the center maintains a larger distance, creating non-uniform local characteristics that prevent multipaction without requiring overall volume increase
Solution Approach 2:
The solution transitions from a uniform one-dimensional distance parameter to a two-dimensional spatial distribution of distances across the conductor strip width, utilizing the transverse dimension to solve the multipaction problem without increasing the longitudinal volume
2Reliability
If the conductor strip size is increased to maintain predetermined impedance when increasing distance from ground planes, then impedance is maintained, but the transmission line becomes bulkier
Solution Approach 1:
Different portions of the conductor strip have different local geometries and distances from the ground plane. The edge portions are closer and narrower while the center is farther and wider, creating local variations that maintain overall impedance without uniform volume increase
3Power
If power in the transmission line is increased, then power handling capability is improved, but multipaction is exacerbated
Solution Approach 1:
The non-uniform distance distribution creates regions of different electric field intensities along the conductor strip. The edges with smaller distances create fringing fields that redirect electrons, while the center maintains appropriate field strength for power transmission, allowing higher overall power without proportional increase in multipaction risk
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design allows for increased power handling without enlarging the transmission line, balancing impedance and multipaction prevention through optimized geometrical changes in the conductor strip and ground plane configuration.
Implementation Method 1
The conductor strip is configured to change an electromagnetic field in the transmission line by creating a fringing electromagnetic field in a vicinity of the first strip portion
Implementation Method 2
Multipaction refers to the phenomenon where an electron excited by the Radio Frequency field impacts the surface of the conductor or ground plane with an energy that is high enough to release one or more secondary electrons from the surface. Under resonant conditions, the direction of the Radio Frequency field is such that the electrons are accelerated towards the opposite surface
Data Source
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AI summary
A microwave transmission line assembly (1) operated in vacuum for satellite antennas and beamforming networks comprising a first ground plane (2) and a conductor strip (4) positioned a distance from the first ground plane (2). The conductor strip (4) comprises a first strip portion (5) and a second strip portion (6). The first strip portion (5) is positioned at a first distance (d1) from the first ground plane and wherein the second strip portion (6) is positioned at a second distance (d2) from the first ground plane (2). The first distance (d1) is smaller than the second distance (2), wherein the first distance (d1) is chosen to avoid multipaction.