Stub Tuners

Triple Stub Tuners


Stub tuners are basic laboratory tools used for matching load impedances to provide for maximum power transfer between a generator and a load, and introducing a mismatch into an otherwise matched system. Typical applications include power and attenuation measurements, tuned reflectometer systems and providing a DC return for single-ended mixers and detectors.

Stub tuners are impedance transformers that are designed to introduce a variable shunt susceptance into a coaxial transmission line. They consist of one or more short-circuited, variable length lines (stubs) connected at right angles to the primary transmission line. Each stub must be movable over one-half wavelength at the lowest frequency of operation in order to provide all possible shunt susceptances; therefore, the low frequency limit of a tuner is determined by the frequency at which the maximum stub travel equals one-half wavelength. Tuners, particularly multiple-stub models, are still usable below this limit. Other than the limitation of the connectors, there is no higher frequency limit; however, various models are offered for size convenience.

The spacing between the stubs of multiple-stub tuners determines the range of impedances that can be matched and the ease of tuning . The stub spacing of Maury triple-stub tuners has been selected for general broadband applications. Triple-stub tuners are more convenient to use since tuning sensitivity is relatively independent of stub spacing.

Maury produces a comprehensive line of broadband stub tuners designed to satisfy the majority of applications. These tuners are available in triple-stub configurations with frequency ranges extending from 0.2 to 18.0 GHz.


Stub Tuner Reference Chart

Swipeable Content
Connector - Model
Stub Travel
Stub Spacing
Type N1
Inches (cm)
Inches (cm)
0.2 - 0.5
30.00 (76.2)
4.6 (11.7) / 2.0 ( 5.1)
0.4 - 1.0
15.00 (38.1)
4.6 (11.7) / 2.0 ( 5.1)
0.8 - 4.0
7.50 (19.1)
1.0 ( 2.5) / 0.75 ( 1.9)
2.0 - 18.0
3.00 (7.6)
0.75 ( 1.9) / 0.5 ( 1.3)
4.0 - 18.0
1.75 (4.4)
0.75 ( 1.9) / 0.5 ( 1.3)
1Precision stainless steel N per Maury data sheet 5E-049.
2Precision stainless steel SMA per MIL-C-39012.

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Application Notes and Data Sheets


Coaxial Stub Tuners Data Sheet 2G-008

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