There are three grades of quality: production, instrument, and metrology. Quality is a measure of the degree of excellence to which the connectors are produced. When looking for connectors you'll need to know what quality level is appropriate for you. Millimeter frequencies above 30 GHz require connectors and cables with smaller conductors. You’ll need to make sure that your hardware can handle the frequency you need to test. The maximum frequency of a coaxial cable can be approximated with the following formula:įor example, this means that a 3.5 mm conductor has a maximum frequency of about 120 / 3.5 = 34 GHz. It’s important to match the characteristic impedance of your cables and connectors to your DUT to minimize reflection.įrequency range is related to the inner diameter of the outer conductor (D). Characteristic impedance is a function of the ratio of the inner and outer conductor diameters (d and D in the figure, respectively).

Connectors are characterized by three main specifications: characteristic impedance, frequency range, and quality.Ĭharacteristic impedance and frequency range can be approximated by the connector’s conductor dimensions. Since RF measurements are so sensitive, you should make sure to consider your connector specifications. The connections between your instrument and your DUT are critical for reliable measurements. Electronic calibration is fast, repeatable, and limits wear on connectors. This process is time-consuming and creates possibilities for user error.Įlectronic calibration modules can electronically replicate the different types of loads with just one connection. A full two-port calibration requires seven mechanical connections.

Operators would individually make each connection and let the instrument take a measurement. Traditionally, calibration is performed with mechanical standards. The network analyzer can apply corrections for cables and connectors by comparing what it measures to the values of the standards. These calibration techniques involve connecting standards with known properties to the measurement setup in place of the DUT. These methods are different combinations of impedance and transmission measurements used to characterize the cables and fixtures for calibration. The two most common methods of calibration are Thru, Reflect, Line (TRL) and Short, Open, Load, Thru (SOLT).

Vna vector network analyzer