Multiplexer Low-Pass Filter T-Junction Cavity Design
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Solution Overview
Problem
Conventional multiplexers face challenges in processing wide frequency bands due to interference between low and high frequency bands, leading to harmonic generation and limitations in simultaneous voice and data transmission.
Innovation Solution
A multiplexer design incorporating a distributed constant type low-pass filter and a common capacitor, connected via a T-junction, separates frequency bands to minimize interference, using a cavity filter with resonators and alternating capacitor and inductor elements to achieve phase matching and broader frequency band communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multiplexer processes a wide range of frequency bands, then the communication speed and data transmission capability are improved, but interference between low frequency band and high frequency band occurs leading to harmonic generation
Solution Approach 1:
The multiplexer is divided into separate processing paths for low frequency band and high frequency band. Each path has dedicated filtering components (low-pass filter for high frequency path, high-pass filter for low frequency path) that operate independently, preventing interference between bands while maintaining wide frequency band processing capability
Solution Approach 2:
Frequency selective filters act as intermediary components between the input signal and the output channels. These filters mediate the signal transmission by allowing only specific frequency bands to pass through each path, thereby preventing harmful interactions and harmonic generation between low and high frequency bands
2Adaptability or versatility
If the difference between low frequency band and high frequency band is doubled to increase processing range, then the frequency band coverage is improved, but interference between bands increases making multiplexer hard to process low-frequency band
Solution Approach 1:
Different parts of the multiplexer are designed with specialized characteristics for their specific frequency ranges. The low frequency path includes high-pass filters and components optimized for low-frequency signals, while the high frequency path includes low-pass filters and components optimized for high-frequency signals. This local optimization ensures reliable processing of low-frequency band despite the wide overall frequency coverage
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 solution effectively reduces harmonic generation and enables simultaneous processing of low and high frequency bands, allowing for broader frequency band communication, simplification of devices, and cost reduction.
Implementation Method 1
a low-pass filter provided inside the housing, electrically connected to the I/O terminal, and formed of a distributed constant type
Implementation Method 2
a cavity filter which includes a plurality of cavities which are formed in the housing and a resonator which is respectively installed in the cavities
Data Source
AI summary
Disclosed is a low-pass filter connected to a capacitor by a T-junction and used for a multiplexer. The low-pass filter includes: a plurality of capacitor elements which is formed of a capacitive conductor of a disk shape; and a plurality of inductor elements which connects the capacitor elements to each other and is formed in a rod shape. The plurality of capacitor elements and the plurality of inductor elements are alternately arranged, and the capacitor element which is connected to the capacitor has a capacitance value smaller than a capacitance value which is determined by a cut-off frequency of the low-pass filter.