The SMA and RP-SMA connectors are two of the most widely used radio frequency connectors. They are critical components in a wide range of telecommunications and wireless networking applications, including cellular networking, Wi-Fi, Bluetooth, Zigbee, LoRa, satcom, and testing and measurement. Because these two cable types are so common, an SMA to RP SMA cable is indispensable for making connections between radio equipment, antennas, and other components in a variety of settings.

An RP-SMA connector is a reversed polarity SMA connector

SMA and RP SMA connectors are almost identical. The only difference is a reversal of the inner mating interfaces of the male and female connectors.

• A male RP SMA has an inner receptacle rather than the conducting pin that is on the male SMA connector.
• The female RP SMA connector carries a conducting pin instead of the receptacle of the standard female SMA connector.

Though this difference is small, it makes SMA and RP SMA connectors physically and electrically incompatible. This incompatibility is deliberate. In the 1990s, electronics manufacturers developed the RP SMA as a compliance measure to deter people from connecting powerful professional antennas to consumer wireless products. Professional equipment routinely carries the SMA connector, while RP SMA connectors are widespread in consumer products.

Physical specifications of the SMA connector

The physical specs of the RP SMA connector are identical, except for the reversed center pin and receptacle (reversed gender). Both male and female SMA and RP SMA connectors are mated by screw-coupling with the tightening of the hex nut on the male connector body. Both types of connectors are rated for 500+ mating cycles. Both connectors come in a variety of formats including right-angled SMA, bulkhead, PCB-mounted SMA connectors, edge-mounted, and panel-mounted.

• Dimensions: the male connector has a diameter of 7⁄16 inches (11 mm) and the female connector has a diameter of 3⁄8 in (9.5 mm)
• Threading: 36 threads per inch
• Material: gold or nickel-plated machined brass with a Teflon insulator
• Male SMA connector: cylindrical body with internalized threads and outer hex-nut for tightening the mated connector with a wrench. Center pin conductor.
• Female SMA connector: cylindrical body with externalized threads, inner beryllium copper receptacle, and silicone rubber gasket

Electrical specifications of the SMA connector.

SMA and RP SMA connectors have identical electrical profiles and performance.

• Nominal impedance: 50 ohms
• Maximum frequency: up to 18 GHz
• Voltage rating: 500 volts.
• VSWR: 1.05 to 1.15 (depending on the attached coaxial cable)
• Contact resistance: 2.0 milliohms.
• Insertion resistance: 5000 megaohms.
• Radio frequency leakage: maximum of -90dB (at 2 to 3 GHz)

SMA to RP SMA cable assemblies

SMA and RP SMA connectors are assembled with a variety of coaxial cables, creating extension cables for antennas and radio equipment. Purchasing a pre-assembled SMA connector cable saves time and provides more reliable results, and you can order custom SMA to RP SMA cables if a specific configuration or length is required that is not readily available.

The compatible coaxial cable gauges for N connector to SMA cables:

• RG55
• RG58
• RG142
• RG141
• RG 174
• RG 316
• LMR-100
• LMR-195