RF Filter With Capacitive Coupling For Frequency-Independent Tuning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current bandpass filters exhibit frequency-dependent characteristics, failing to meet legal emission requirements and wireless communication specifications across a predefined frequency tuning range due to the frequency-dependent coupling between resonators, which affects the passband width and selectivity.
Innovation Solution
The design incorporates coaxial transverse electromagnetic wave mode resonators with adjustable coupling elements, allowing for frequency-independent passband width and selectivity through spatial arrangement adjustments, including translatory and rotational movements of non-conductive actuating elements, and the use of distributed capacitance to minimize frequency dependency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the filter uses electromagnetic coupling structures with adjustable resonator rods to enable frequency tuning, then the filter can be tuned to different center frequencies, but the filter characteristics become frequency dependent and cannot fulfil specific legal emission requirements or wireless communication specifications over the predefined frequency tuning range
Solution Approach 1:
The patent changes the coupling mechanism from electromagnetic coupling (which is frequency-dependent) to electrostatic coupling using coupling capacitors. This parameter change in the coupling mechanism eliminates frequency dependency while maintaining the ability to tune the filter to different center frequencies by adjusting resonator rod lengths, thus resolving the contradiction between tuning capability and compliance reliability
Solution Approach 2:
The patent replaces the electromagnetic coupling mechanism with an electrostatic coupling mechanism using capacitors. This substitution changes the physical principle from electromagnetic fields to electrostatic fields, which provides frequency-independent coupling characteristics while preserving the mechanical tuning capability through adjustable resonator rods
2Manufacturing precision
If the filter bandwidth is adjusted to meet filter mask requirements at lower center frequencies, then the passband part cannot exceed the first margin of the filter mask, but this creates frequency dependency in the passband width
Solution Approach 1:
The patent changes the coupling mechanism to electrostatic coupling using capacitors, which provides frequency-independent coupling characteristics. This allows the passband width to remain consistent across different center frequencies while still meeting filter mask requirements, resolving the contradiction between manufacturing precision and compositional stability
3Manufacturing precision
If the filter bandwidth is adjusted to meet filter mask requirements at higher center frequencies, then the filter curve cannot fall below the second and third margins of the filter mask, but this creates frequency dependency in the frequency selectivity
Solution Approach 1:
The patent changes the coupling mechanism to electrostatic coupling using capacitors, which provides frequency-independent coupling characteristics. This maintains consistent frequency selectivity across the entire tuning range while ensuring compliance with filter mask requirements at all frequencies
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 approach enables a frequency-independent spectral characteristic and flexible tuning for bandpass filters, ensuring compliance with spectral requirements across a predefined frequency range while reducing manufacturing and storage costs by allowing the same filter type to be used for various center frequencies.
Implementation Method 1
The coupling elements (102a, 102b) are connected to said connecting element (104) in an electrically conductive manner, and the connecting element (104) is mechanically supported by and electrically isolated from said separating means (ISP1) by suitable supporting means (108), thereby defining an electrically conductive structure which - mainly capacitively - couples the resonator cavities
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a Filter (FL1) for radio frequency, RF, signals comprising a first cavity resonator (RC2), a second cavity resonator (RC5), separating means (ISP1) separating said first cavity resonator (RC2) and said second cavity resonator (RC5), and coupling means (100) for capacitively coupling said first cavity resonator (RC2) and said second cavity resonator (RC5), wherein said coupling means (100) comprise a connecting element (104) protruding through an opening (OP1) in said separating means (ISP1), a first coupling element (102a) that is arranged in said first cavity resonator (RC2) and that is connected to said connecting element (104), a second coupling element (102b) that is arranged in said second cavity resonator (RC5) and that is connected to said connecting element (104), wherein at least one of said coupling elements (102a, 102b) is movably attached to said connecting element (104) and/or said connecting element (104) is rotatably attached to said separating means (ISP1).