Introduction LRR is 1. new self-calibration procedure for

calibration of vector network analyzer(VNA).

VNA measure the complex transmission and reflection characteristics of microwave devices.

VNAs need to be calibrated to eliminate the systematic errors from complex measurement results.

Calibration structure Consists of partly unknown standards

L= line element

R= reflection standard Obstacles= symmetrical reciprocal networks

placed at 3 consecutive positions. Can be easily realized by microstrip

technology. [G],[H] = systematic errors to be eliminated

during calibration.

Microwave devices

Devices which operate with a signal frequency range of 1-300 GHZ.

Tunnel diode Transferred electron device Avalanche transit-time devices

Two port network in microwave frequency range

A microwave system

Various parts Transmitter subsystem:- microwave oscillator waveguides transmitting antenna Receiver subsystem:- receiving antenna waveguide microwave amplifier receiver

VNA(vector network analyzer)REF Signal

ToR Signal

Reflectometer Receiver

External PC

Display system

LRR Technique

incident signal

REF Signal tra ref

Microwave sources

Test setMicrowave

device

Display system Receiver Reflectometer

External PC

Microstrip lines Provide one free and accessible surface

on which solid state device can be placed.

It is a parallel plate transmission line. Consists of a dielectric substrate, one

face is metalized ground and other face has a thin conducting strip of certain width ‘w’ and a thickness ‘t’.

Merit: such lines are easily fabricated by printed circuit manufacturing technology.

Figure of microstrip lines

ADVANTAGES

The complexity of the test fixture can be reduced.

The connectors of the VNA do not have to be placed at different distances than each other during calibration.

Enlargement of bandwidth. Improved accuracy.

Drawbacks

Difficult to obtain an obstacle whose electrical properties must not change when it is moved.

More line standards are needed to cover a wide frequency range.

An approximate knowledge of circuit dimensions is necessary in order to choose the correct solution.

Applications

In free space systems where the variation of the antenna positions might be critical due to change in beam propagation.

When test fixtures need to be simple. When the connectors of the analyzers

measurement ports cannot be displaced.

Conclusion

Advantageous for calibration of VNA where connectors of VNA ports cannot be displaced.

In the LRR method two solutions are

there and depending on the realized calibration structures, the appropriate way should be chosen in order to improve the accuracy.

References Samuel.Y.Liao, Microwave devices and circuits, PHI. Kulkarni, Microwave and Radar Engineering. Cletus A.Hoer, “performance of a dual six-port

automatic network analyzer,” IEEE Transactions Microwave Theory and Techniques,vol- 27, No.12,Dec 1979.

www.networkanalyzer.com Ilona Rolfes and Burkhard Schiek, “LRR-A Self-

Calibration Technique for the Calibration of Vector Network Analyzers,” IEEE Transactions on instrumentation and measurement, vol 52, No. 2, pp.316-319, April 2003.

THANK YOU!!

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