Air-Isolated Coaxial Line Radially Adjustable Piston RF Mismatch Testing

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Solution Overview

Problem

Existing methods for through-line mismatch RF testing are compromised by the need to disconnect the Device Under Test from other equipment, leading to inaccurate measurements due to mismatches and reflections, especially when using RF switch relays and additional cables, making the mismatch device unpredictable.

Innovation Solution

An air-isolated coaxial line with a radially adjustable piston connected to the shielding, allowing for controlled capacitive loads to be added or removed, effectively adjusting the impedance and minimizing reflections, thereby maintaining high RF performance when the load is set to zero.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If RF switch relays and additional cables are used to connect test devices to the DUT, then the ability to perform comprehensive testing is improved, but measurement accuracy deteriorates due to mismatches and reflections

Engineering Contradiction:

Improvetesting capabilityVSAvoidmeasurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent introduces a mismatch device as an intermediary component placed between the test equipment and the DUT. This mediator deliberately introduces controlled mismatches to compensate for the unwanted reflections and mismatches caused by the relay and cable connections, thereby restoring measurement accuracy while maintaining comprehensive testing capability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a variable mismatch device that can change its impedance parameters dynamically. By adjusting the mismatch device's characteristics, the system can compensate for different relay and cable configurations, maintaining measurement accuracy across various testing scenarios without sacrificing versatility

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a mismatch device is placed behind relays and additional cables, then the ability to simulate non-perfect load situations is improved, but the unpredictability and uncertainty of the mismatch increases

Engineering Contradiction:

Improvemismatch simulation capabilityVSAvoidmismatch predictability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements a mismatch device that is pre-calibrated and positioned before the relays and cables in the signal path. This preliminary placement allows the mismatch characteristics to be established and controlled at a known reference point, eliminating the uncertainty that would otherwise arise from the cumulative effects of multiple connectors and cables

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

By positioning the mismatch device as a controlled intermediary component at a defined location in the signal path, the patent creates a stable reference point for mismatch simulation. This mediator approach ensures that the mismatch characteristics remain predictable and reliable, independent of the subsequent relay and cable configurations

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If the DUT is disconnected from other test equipment to perform mismatch testing, then the accuracy of mismatch measurement is improved, but the productivity and efficiency of testing deteriorates

Engineering Contradiction:

Improvemismatch measurement accuracyVSAvoidtesting efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent designs a mismatch device that can function universally in conjunction with various test equipment and relay configurations. Rather than requiring disconnection from other equipment, the mismatch device integrates into the existing test setup, enabling simultaneous performance of mismatch measurement and other testing operations, thereby maintaining high productivity while ensuring measurement accuracy

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 enables precise and controlled mismatch testing without disconnecting the Device Under Test, ensuring accurate measurements and high RF performance by allowing the transmission line to act as a through-line with minimal influence on other test equipment, and can withstand high RF power with no power loss.

Implementation Method 1

adding a capacitive load thereto and thereby lowering the impedance of the influenced part of the transmission line

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS8803531B2Method and arrangement for through-line mismatch RF testing

Publication Date: 2014.08.12 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method and arrangement for facilitating through-line mismatch RF testing using an air-isolated coaxial line having an inner conductor surrounded by a coaxial shielding. At least one circular opening is provided through the shielding. A radially adjustable piston is provided in each opening such that it is electrically connected to the shielding and such that its protrusion from an inside of the shielding towards the inner conductor is adjustable. The position of the radially adjustable piston is calibrated with a known level of RF mismatch so that a desired level of mismatch can be created through adjustment of the piston. By adjusting the piston so that it does not protrude beyond the inside of the shielding, the arrangement is effectively set to zero and does not have to be disconnected after use.