Stub Tuners

Information

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.
1819C

Stub Tuner Reference Chart

Swipeable Content

Type	Frequency Range (GHz)	Connector - Model		Stub Travel	Stub Spacing
Type	Frequency Range (GHz)	Type N¹	SMA²	Inches (cm)	Inches (cm)
Triple-Stub	0.2 - 0.5	1878G	---	30.00 (76.2)	4.6 (11.7) / 2.0 ( 5.1)
	0.4 - 1.0	1878A	1819A	15.00 (38.1)	4.6 (11.7) / 2.0 ( 5.1)
	0.8 - 4.0	1878B	1819B	7.50 (19.1)	1.0 ( 2.5) / 0.75 ( 1.9)
	2.0 - 18.0	1878C	1819C	3.00 (7.6)	0.75 ( 1.9) / 0.5 ( 1.3)
	4.0 - 18.0	1878D	1819D	1.75 (4.4)	0.75 ( 1.9) / 0.5 ( 1.3)