Introduction to connector technology：
Connector, ie (CONNECTOR). Domestic also known as connectors, plugs and sockets. Generally refers to the electrical connector. That is, devices that connect two active devices, transmit current or signal. It is widely used in aviation, aerospace, defense and other military systems. The connector is a component that we often contact with an electronic engineering technician. Its role is very simple: in the circuit is blocked or isolated between the circuit, set up a bridge of communication, so that the current flow, so that the circuit to achieve a predetermined function. The connector is an indispensable part of the electronic device, along the current flow path observed, you will always find one or more connectors. Connector form and structure is ever-changing, with the application of objects, frequency, power, application environment, etc., there are different forms of connectors. So how do we correctly choose the RF connector, how to determine the cable assembly, how to calculate the insertion loss, voltage standing wave ratio? Let's take a brief look at the technical aspects of these connectors.

What factors should be considered when choosing a radio frequency connector?
There are many factors that determine the connector series and style, where the adapter cable and the frequency range used are the main factors. In engineering practice, the connector diameter and cable diameter as close as possible to minimize the reflection. The greater the difference between the cable diameter and the connector diameter, the worse the performance. Reflections usually increase as a function of frequency, while generally smaller connectors are usually very good in high frequency bands. For very high frequencies (above 26 GHz), a precision air media connector is required.

Voltage standing wave ratio (VSWR) and its determination？
VSWR (Voltage Standing Wave Ratio) is the metering signal from the connector to return the amount of measurement standards. It is a vector unit that includes amplitude and phase components. It is important to understand this, especially when we consider the composite effects of multiple connectors on the transmission line. Impedance mismatch can cause reflections. If the cable used is 50 ohm impedance, the connector must also maintain a 50 ohm impedance. From the cable to the connector on the transmission line size conversion, the connector within the dielectric media and the conductor contact loss is the main factor leading to non-matching. There are usually two ways to determine the VSWR of the connector. The first method is to use the "flat linear limit" method over the entire frequency band. For example, for a straight BNC plug with a flexible cable, the VSWR specifies a maximum of 4 GHz 1.3: 1 (usually written as max 1.3). The second method is to take into account the VSWR in the actual case is a typical direct function of the frequency, with RG-142 B / U cable straight SMA plug, VSWR can be described as: VSWR = 1.15 +0 .01 * F ( GHz) to 12.4 GHz maximum frequency. For example, at 2 Ghz, the maximum allowable VSWR will be 1.15 + 2 * .01 or maximum 1.17. At 12.4 Ghz it will be 1.15 + 12.4 * .01 or maximum 1.274. Naturally, these values ​​can be converted to return loss or reflection coefficients.