Dielectric Resonator Rod Tapered Surface RF Filter
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Solution Overview
Problem
Traditional dielectric resonator filters in transverse magnetic mode suffer from poor spurious performance due to the close proximity of higher-order resonant modes to the fundamental resonant mode, making it difficult to suppress spurious emissions effectively.
Innovation Solution
A dielectric resonator rod with a tapered outer circumferential surface connecting two cylindrical end parts of different diameters, which increases the frequency spacing between the fundamental and higher-order resonant modes, allowing for effective suppression using a low pass filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If step resonators with different diameters are applied to reduce filter volume, then the compactness of the RF filter is improved, but the spurious performance deteriorates due to poor separation between fundamental and higher-order resonant modes
Solution Approach 1:
The dielectric resonator is designed with non-uniform diameter along its length, creating different local geometries (larger diameter at one end, smaller at the other) to selectively control resonant modes. This local variation in geometry allows the fundamental mode to be well-separated from higher-order modes while maintaining compact dimensions, resolving the contradiction between small size and good spurious performance
Solution Approach 2:
The invention changes the geometric parameters of the dielectric resonator by implementing a diameter gradient along its length rather than using uniform or stepped diameters. This continuous parameter variation optimizes the separation between resonant frequencies, enabling both compact filter volume and suppressed spurious emissions to be achieved simultaneously
2Object-generated harmful factors
If a low pass filter is applied to suppress higher-order resonant modes, then the spurious emissions are reduced, but the transition band becomes too long to effectively separate close-spaced resonant frequencies
Solution Approach 1:
The dielectric resonator geometry is pre-designed to inherently separate the fundamental and higher-order resonant modes in frequency before the low pass filter is applied. This preliminary frequency separation, achieved through the diameter-gradient structure, allows a standard low pass filter with normal transition band characteristics to effectively suppress spurious emissions without requiring an excessively long transition band
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 enhances spurious suppression, enabling a compact RF filter with improved separation of resonant modes, reducing the filter volume by approximately 40% while maintaining or exceeding the quality factor of prior art designs.
Implementation Method 1
one dielectric resonator can support a variety of resonant modes, which causes the frequency spacing between the desired fundamental resonant mode frequency and higher-order resonant modes frequency to be quite narrow
Data Source
AI summary
The invention relates to a dielectric resonator rod in a transverse magnetic mode radio frequency filter comprising a first cylindrical end part (10) of a first diameter (D1) and a second cylindrical end part (20) of a second diameter (D2). The first diameter is different than the second diameter and the first cylindrical end part (10) is connected via a third intermediate part (30) to the second cylindrical end part (20). The third intermediate part (30) comprises a tapered outer circumferential surface connecting the first cylindrical end part (10) to the second cylindrical end part (20).