Opens

General Information

Shielded, coaxial opens are used in the calibration of vector network analyzers to provide a nominal 180° phase offset from a compatible reference short over a wide range of frequencies.

At these frequencies, open circuit terminations are inherently imperfect. Shielding the open essentially eliminates radiation loss, but creates a residual frequency-sensitive capacitance. An accurate knowledge of the open’s effective capacitance is essential to an accurate calibration of the analyzer.

Maury opens are characterized for effective capacitance versus frequency by means of a fourth order polynomial curve fit, and the nominal capacitance coefficients are provided with each unit. We offer several innovative designs that improve the consistency and repeatability of the open’s capacitance coefficients resulting in improved effective source match of the calibrated VNA1.

One design (seen in the 7mm models shown below) uses a beadless captivated dielectric rod in place of the center conductor contact. This rod depresses the spring-loaded contact of the test port connector so that it is flush with the outer conductor mating plane. This creates highly accurate, precisely repeatable open circuit conditions which improve the calibration effectiveness and measurement accuracy of the open.

Another design (seen in most of the sexed models listed below) uses a center contact that is captivated and set at the factory to be essentially flush with the outer conductor mating plane, thereby eliminating dependence on test port connector tolerances and adding a high degree of performance consistency to the open.

The 371N2/P2 and 8585A1/B1 models are designed for limited frequency ranges as determined by their connector types.

In all cases, the specification "Phase Accuracy" phase deviation from a nominal unit.


Available Models

Swipeable Content
MODEL
SEX
CONNECTOR TYPE
FREQUENCY RANGE (GHZ)
PHASE ACCURACY
MINIMUM REFLECTION COEFFICIENT
7948A1
7948B1
female
male
2.4mm
DC – 50.0
±2.0°
0.98
8773A2
8773B2
female
male
2.92mm (K)
DC – 40.0
±1.5°
0.98
8048A1
8048B1
female
male
3.5mm
DC – 26.5
±1.4°
0.98
2616D3
-
7mm
DC – 18.0
±0.3°
0.995
8809B1
8810B1
female
male
Type N
DC – 18.0
±2.0°
0.99
8609B
8610B
female
male
TNC
DC – 18.0
±5.0°
0.98
371N2
371P2
female
male
BNC 50Ω
DC – 12.4
±5.0°
0.98
8585A1
8585B1
female
male
BNC 75Ω
DC – 12.0
DC – 2.0 = ±1.0°
2.0 – 3.0 = ±2.0°
3.0 – 12.0 = ±6.0°
0.98
1See Maury data sheet 5C-027

Application Notes and Data Sheets

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