A sliding termination (or sliding load) consists of a precision, movable, tapered termination in a highly accurate, air dielectric transmission line.
These instruments are basic tools for precision microwave measurements. One general application is "load separation" measurements in which the reflection from the terminating element can be separated from that of the test device. Load separation using sliding loads is a key element in the calibration of vector network analyzers (VNAs). The technique is also used in the measurement of the reflection from two-port devices, particularly "non-insertable", (e.g., waveguide-to-coax adapters, and the directivity of directional couplers).
A sliding short is a movable short circuited termination in a precision air line which is used in a variety of laboratory measurement applications. These devices are used to establish a reference plane in a transmission system, as tuning elements in the development of microwave components (mixers, amplifiers, etc.), and tuning high precision CW reflectometer systems. An important application is the calibration of vector network analyzers (VNA). The use of a sliding short for such a calibration is particularly effective when the VNA is to be used for the measurement of highly reflective devices.
Shielded, coaxial open circuit terminations ("opens") are used in the calibration of both scalar and vector network analyzers (SNA and VNA, respectively). In both applications, they are used to provide a nominal 180 degree phase offset from a compatible reference short circuit over a broad range of frequencies.
Precision or reference air lines are air-dielectric transmission lines with highly accurate dimensions that can be used in measurement and calibration applications as fundamental impedance standards and to establish reference positions for measurements.
Maury offers bead supported and beadless connectors in air lines using 2.4mm, 2.92mm, 3.5mm, 7mm, type N, 14mm and 7-16 connectors. Beadless lines offer better impedance and electrical length accuracies and lower VSWR, while beaded lines offer greater convenience.
Precision standard mismatches are fixed coaxial terminations which are used to introduce a known VSWR into a 50 ohm transmission system. These mismatches are extremely useful in a wide variety of applications and are quick and easy to use. They can be used to calibrate swept reflectometers, verify network analyzer calibration, establish impedance references in TDR measurements, etc.
Mismatch air line sets are two-port, 1/4 wavelength VSWR standards consisting of coaxial air lines employing a precision outer conductor with beadless connectors and a set of inner conductors with increasing diameters. These produce accurately known reflection coefficents which are directly calculable from and traceable to air line dimensions.
Air line standard sets are extremely stable and easy to use for a variety of applications. The simple geometry allows direct calculation of reflection, loss, transfer and group delay characteristics, making them ideally suited for checking the performance and accuracy of network analyzers.
The sets described here utilize beadless connectors and rely on the mating connectors for center conductor support.