Capacitively Coupled Duplexer Housing for PIM Measurement
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Solution Overview
Problem
Current PIM measurement devices face limitations in achieving self-intermodulation levels below −175 dBc due to galvanic contacts in filter structures, which are prone to degradation and instability, leading to insufficient testing capabilities for components specified at −165 dBc.
Innovation Solution
The implementation of a duplexer with a monolithic metal housing and a capacitively coupled aluminum cover without galvanic contact, using dielectric layers and glass fiber reinforced plastic screws to ensure capacitive coupling, and additional shielding to minimize PIM creation and enhance long-term stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If galvanic contacts are used in filter structures, then electrical connectivity is achieved, but PIM levels deteriorate and long-term stability is compromised
Solution Approach 1:
The patent removes galvanic contacts from the filter structure by using a monolithic housing design where the housing itself serves as the RF ground reference. This extraction of the problematic galvanic contact interface eliminates the source of PIM generation while maintaining electrical connectivity through the monolithic structure.
Solution Approach 2:
The patent merges the housing structure with the RF ground reference, creating a monolithic design where the housing body and RF ground are electrically connected as one integrated structure. This eliminates separate galvanic contacts between housing and ground planes, thereby reducing PIM.
2Measurement precision
If conventional filter structures with galvanic contacts are used, then manufacturing is simplified, but measurement precision deteriorates due to insufficient PIM performance
Solution Approach 1:
The patent replaces mechanical galvanic contacts with a monolithic structural design where electrical connectivity is achieved through the integrated housing structure itself. This substitution eliminates the need for separate contact interfaces while achieving the required PIM performance for precise measurements.
3Reliability
If galvanic contacts are used in duplexer structures, then assembly is facilitated, but self-intermodulation levels worsen, preventing achievement of −175 dBc
Solution Approach 1:
The patent combines the duplexer housing with the RF ground reference into a monolithic structure, eliminating galvanic contacts between these components. This merging achieves the required self-intermodulation performance better than −175 dBc while the housing itself provides the structural framework.
Solution Approach 2:
The patent segments the electrical connectivity function from the mechanical housing structure by using the monolithic housing as the RF ground reference, separating the concerns of mechanical assembly from electrical performance requirements.
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 achieves self-intermodulation levels better than −175 dBc, reducing PIM creation and improving measurement accuracy, while maintaining linearity and stability, thus enabling effective testing of components with stringent specifications.
Implementation Method 1
A metal cover (780) is capacitively coupled to the filter housing body (700) without galvanic contact
Implementation Method 2
at least one of the cover (780) and the housing body (700) has a dielectric layer
Data Source
AI summary
A PIM test bench including a first duplexer, having a first port connected via a first filter to a third port and a second port connected via a second filter to the third port. The first port is fed by signal sources providing RF signals at first and second frequencies. A spectrum analyzer is connected to the second port. A device under test is connected between said third port and a third port of a second duplexer. Each of the first and second ports of the second duplexer is connected to a PIM optimized load and/or a standard load. The second duplexer is preferably identical to the first duplexer. For minimizing self-intermodulation, at least the first duplexer comprises at least one filter component and a metal housing. The housing further includes a monolithic metal body and a metal cover capacitively coupled to the body without any galvanic contact.