Vector Network Analyzer Calibration Using Comb Generator
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Solution Overview
Problem
Conventional vectorial network analyzers face significant measurement errors at medium to high frequencies, and existing calibration methods require numerous through connections, making them costly and impractical for measuring linear and non-linear parameters, especially for devices with a large number of ports.
Innovation Solution
A method and device for calibrating vectorial network analyzers that utilize a comb-generator signal and a power meter to perform phase and impedance measurements without through connections, allowing for phase-synchronous, frequency-translating measurements, and enabling the calculation of error networks for correction, using a simplified auto-calibration unit with three single-port standards and a power meter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods are used for vectorial network analyzers, then measurement accuracy can be improved, but the number of through connections required increases significantly
Solution Approach 1:
The patent extracts the essential calibration function from complex multi-port through connections and implements it using a simplified auto-calibration unit with three single-port standards. This removes the burden of establishing numerous through connections while preserving the core calibration capability needed for measurement accuracy.
Solution Approach 2:
The patent introduces an intermediary auto-calibration unit that mediates between the vectorial network analyzer and the calibration standards. This unit uses a comb generator to create multiple frequency signals and a power meter to measure them, enabling calibration without direct through connections between all ports.
2Measurement precision
If conventional calibration methods are used, then system-error correction can be achieved, but the cost and practicality decrease for devices with large numbers of ports
Solution Approach 1:
The patent implements a self-service calibration system where the vectorial network analyzer performs its own calibration using the auto-calibration unit. The system uses software control to automatically execute calibration routines, eliminating the need for manual through connections and reducing both cost and complexity for multi-port devices.
Solution Approach 2:
The patent changes the calibration approach from physical through connections to electrical parameter measurements using a comb generator. By measuring power at different frequencies and calculating error coefficients mathematically, the system achieves system-error correction without the physical complexity of through connections.
3Ease of manufacture
If scalar measurement methods are used for non-linear parameters, then cost is reduced, but measurement accuracy and system-error correction are lost
Solution Approach 1:
The patent creates a universal calibration system that handles both linear and non-linear measurements with the same auto-calibration unit. The comb generator produces multiple frequency signals that enable the system to measure fundamental frequencies, harmonics, and inter-modulation products, providing multi-functionality at a cost similar to scalar measurements but with vectorial accuracy.
Data Source
AI summary
A vectorial network analyzer including n test ports. With the connection of several different calibration standards to the test ports, several calibration measurements are implemented. For the calibration, different measurements are implemented. Initially, in n calibration measurements, a comb-generator signal is supplied via a direct connection successively to all n test ports. Using a measuring point at the output of the comb generator and the measuring point associated with the respective test port, phase measurements are implemented at all of the frequencies forming the comb-generator signal. A frequency-dependent phase offset is determined from the phase measurements. Moreover, in at least one measurement, all n test ports are terminated successively in each case using known, input impedances, identical within one measurement, of arbitrary transmission properties, wherein successively, all n test ports are excited using a transmission oscillator successively with all frequencies of the comb-generator signal.