Low Pass Filter With Non-Uniform Stubs For High Power
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Solution Overview
Problem
Conventional low-pass waveguide filters have limitations in rejecting high frequencies, requiring complex designs like waffle-iron filters or concatenating corrugated filters with Bragg reflection structures, which result in devices that are either power-restrictive or excessively long.
Innovation Solution
A low-pass filter with a rectangular tubular section featuring a continuous series of rejection elements, such as sinusoidal stubs without separation, is designed to achieve a large rejection bandwidth and high power handling with a reduced length, utilizing three differentiated areas for optimal frequency rejection and power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If waffle-iron filter design is used to reject high frequencies up to the third harmonic, then frequency rejection performance is improved, but power transmission capability deteriorates due to very small physical gaps
Solution Approach 1:
The filter structure transitions from a uniform design to a non-uniform design where the gap size varies along the propagation direction. The gap is smallest at the center and progressively increases toward the ends, allowing different sections to serve different functions: the central region provides frequency rejection while the end regions with larger gaps facilitate power transmission.
2Measurement precision
If Bragg reflection structure is concatenated with corrugated filter to reject up to the third harmonic, then frequency rejection performance is improved, but device length increases significantly
Solution Approach 1:
The invention merges the frequency rejection function and the power transmission function into a single integrated structure. The non-uniform gap design allows the same filter structure to simultaneously reject frequencies up to the third harmonic and transmit high power, eliminating the need for separate concatenated structures.
3Power
If corrugated filter is used for high power transmission, then power capability is improved, but frequency rejection performance deteriorates as it cannot reject up to the third harmonic
Solution Approach 1:
The gap dimension parameter is varied along the propagation direction to achieve multiple functions. By changing the gap size from small at the center to large at the ends, the structure achieves both high frequency rejection (requiring small gaps) and high power transmission (requiring large gaps) simultaneously.
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
The filter effectively rejects frequencies up to the third harmonic with minimal gap, allowing high power transmission and maintaining compact size, achieving good return losses and abrupt slope between passband and rejection band.
Implementation Method 1
patent US 2007024394 describes a device that is formed from a high-power corrugated low-pass filter (which does not allow rejecting up to the third harmonic), at the output of which there is added a structure based on the Bragg reflection phenomenon
Data Source
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AI summary
The invention relates to a low-pass filter for electromagnetic signals, made up of a series of rejection elements defined by stubs (2) of length λg/4, with a small or zero distance between them, these elements being tuned to different frequencies determining the rejection band.