Main specifications of RF connectors

Impedance: Almost all RF connectors and cables are standardized to 50Ω impedance. The only exception is that 75Ω systems are commonly used in cable TV installations. It is also important that the RF coaxial cable connector has a matching characteristic impedance of the cable. If this is not the case, a discontinuity is introduced and loss may result.

VSWR (Voltage Standing Wave Ratio): Ideally, it should be unity. Good design and implementation can keep VSWR below 1.2 within the range of interest.

Frequency range: Most radio frequencies now work in the range of 1 to 10 GHz, so the connector must have low loss in this area. For the case above 10 GHz-there are a lot of things that work in the 10 to 40 GHz range now-there are newer connectors among them to choose. They are expensive because of the cable itself.

Insertion loss: This is the connector loss in the frequency range of interest. The loss is usually between 0.1 and 0.3 decibels. How critical per watt (or fractional watt) is determined is that in most designs, even such a small loss must be minimized and included in the link loss budget. It is in the low-noise front end, especially when the signal strength and signal-to-noise ratio are low.

Operating cycle: How many connection/disconnection cycles can be connected and still meet its specifications? This is usually 500 or 1000 cycles. For threaded connectors, the tightening torque specified by the supplier is an important factor in maintaining performance and reliability.

Power: Power handling is determined by the two resistance losses (heating) and insulation breakdown. Although even decades of design are mainly pre-processing dozens of watts, today's design community focuses on low-power devices such as mobile phones, picocells and femtocell base stations, video interfaces, RF and gadgets. These are in the sub 1W range, so the connector can be much smaller and its power rating is a smaller constraint.