Overview of VNA test cable and calibration methods

In today's competitive electronics industry,VNA test cable reliability is critical for applications using microwave/RF cable assemblies, which need to ensure consistent, repeatable test results and maintain reliable electrical performance over time. Therefore, cable assemblies must be durable enough to withstand constant movement, bending, and a variety of environmental conditions, while maintaining reliable electrical performance. Continuous, frequent cable movement can compromise the measurement accuracy of high-performance vector network analyzers (VNAs). However, recent studies have shown that more than 75 percent of microwave/RF cable assemblies worldwide require frequent replacement due to damage caused during installation. The actual method of calibration although the general VNA test cable User Guide has the instrument calibration method, many details need to be noted.

The following is a directory listing:

• Setting test parameters

• Selecting Calibration Parts

• Checking calibration results

Setting test parameters

Select the test frequency range: the general frequency range should be slightly greater than the range specified in the test index and select the VNA Port excitation power. For passive devices, you can choose a slightly larger excitation power, such as 0dBm. But for testing the Amplifier and other small signal devices, the general excitation signal is to be less than the device's 1dB compression point. For Power Amplifiers and other Large power devices, the need to reduce the input signal power of the VNA test cable, while the PA output and VNA test cable input to add attenuators. However, excessively reducing the input signal power of the VNA test cable may make the measurement error of S11 and S22 increase. If the multi-port VNA test cable, you also need to select the test port

Selecting Calibration Parts

Select calibration parts, choose the calibration method, and finish the calibration by the guide of instrument calibration. Each company has different specifications of calibration parts, such as N type, and SMA type, which must be selected before calibration. Because the manufacturers provide calibration parts, such as open circuit short circuit load does not have the ideal reflection coefficient of 1, -1, and 0. The same company's VNA test cable will define the calibration parts and the characteristics of the calibration parts in advance of the VNA test cable. The calibration device is defined in the VNA test cable of the same company, and its characteristics are stored in the VNA test cable in advance so that the error equation can be solved during calibration. During the calibration process, the display format does not affect the calibration, you can choose to display S11 or S21, or the display can be VSWR or Smith Chart. This does not affect the calibration. Take SOLT as an example, first of all, for single port calibration, add an open short circuit load to port1 and port2 of VNA respectively. It follows the instruction of the instrument to complete the calibration and then connects thru parts to complete the straight-through calibration.

Checking calibration results

This step is not necessary, but I think as a good RF engineer. This step is crucial. VNA test cable calibration result check includes open circuit calibration characteristics check, load calibration characteristics check, through check three.

If you want to know more information about the solderless VNA test cable, welcome to consult us. Our website is www.rfcnn.com