Component Selection and Comparison Practical Selection Questions Selection

How do I select the right connector family for a given frequency range and application?

Selecting the right connector family for a given frequency range and application matches the connector's electrical performance (frequency rating, insertion loss, return loss, power handling), mechanical characteristics (size, mating cycles, vibration resistance), and environmental capabilities (temperature range, sealing, corrosion resistance) to the system requirements. The primary connector families and their frequency ranges are: Type N (DC to 11 GHz, standard; DC to 18 GHz, precision): the workhorse for test and measurement and military applications below 18 GHz. Available in 50 and 75 ohm versions. Threaded coupling. Moderate size (approximately 16 mm diameter). SMA (DC to 18 GHz, standard; DC to 26.5 GHz, precision): the most widely used RF connector for PCB and module applications. Compact (approximately 8 mm hex). Threaded coupling. Available in standard, precision, and hermetic seal versions. 3.5 mm (DC to 34 GHz, standard; DC to 36.5 GHz, precision): mode-free operation to 34 GHz. Mechanically compatible with SMA (can mate with SMA but the SMA limits the frequency to 18-26.5 GHz). Used for test and measurement. 2.92 mm / K connector (DC to 40 GHz): developed by Wiltron/Anritsu. Mates with SMA and 3.5 mm. Used for 40 GHz test equipment and modules. 2.4 mm (DC to 50 GHz): smaller bore, higher frequency. Does not mate with SMA or 3.5 mm. Used for mmW test and high-frequency interconnects. 1.85 mm / V connector (DC to 67 GHz): developed by Anritsu. Used for 67 GHz VNA interconnects and mmW modules. 1.0 mm (DC to 110 GHz): the highest-frequency coaxial connector. Used for W-band and mmW testing. Very fragile, limited mating cycles. Selection criteria: choose the connector family whose frequency rating exceeds the system's highest operating frequency by at least 10-20%, then select the specific version (standard vs. precision, sealed vs. unsealed, panel-mount vs. cable-mount) based on the mechanical and environmental requirements.

Category: Component Selection and Comparison

Updated: April 2026

Product Tie-In: All Components

RF Connector Family Selection Guide

Connector selection is often underestimated in RF system design, yet an improperly selected connector can degrade the system performance, create reliability issues, and increase long-term maintenance costs.

Selection Decision Matrix

Below 6 GHz: Type N or SMA are both suitable. Type N: preferred for higher power (up to 300 W CW at 1 GHz), test equipment, and outdoor installations (better weatherproofing with N-type weatherproof versions). SMA: preferred for compact designs, PCB mounting, and module interconnects
6-18 GHz: SMA is the standard. Ensure the SMA connector quality is adequate (precision SMA for measurement, standard SMA for production). Type N can be used up to 11-18 GHz but is bulkier
18-40 GHz: 2.92 mm (K) is the standard. Backward compatible with SMA (useful for transitioning from lower-frequency testing). 3.5 mm for measurement applications
40-67 GHz: 2.4 mm or 1.85 mm (V). Higher cost, more fragile. Require careful handling and torque wrench mating

Connector Performance Parameters

Connector insertion loss (typical, per mating pair):
SMA: 0.1 dB at 10 GHz, 0.3 dB at 18 GHz
2.92mm: 0.15 dB at 20 GHz, 0.4 dB at 40 GHz
1.85mm: 0.3 dB at 40 GHz, 0.6 dB at 67 GHz
Return loss: > 20 dB (standard), > 30 dB (precision)
Mating cycles: 500 (standard), 5000+ (precision)

Common Questions

Frequently Asked Questions

When should I use precision connectors?

Use precision connectors for: test and measurement setups (where connector repeatability affects the measurement accuracy), calibration standards (require the highest grade connectors), and system interfaces where return loss greater than 26 dB is required. The cost difference: precision connectors cost 3-10× more than standard connectors but provide much tighter specifications for return loss, insertion loss, and repeatability. For production hardware: standard connectors are adequate for most applications where return loss greater than 20 dB is sufficient.

What about push-on connectors?

Push-on (snap-on) connectors like SMP, SMPM, and GPPO provide: quick mating without threading (useful for production and field maintenance), very compact size (approximately 3-5 mm), limited mating cycles (100-500 for standard, up to 40,000 for SMPM with smooth bore), and good performance to 40-65 GHz depending on the connector type. Used for: board-to-board interconnects inside equipment, test fixtures where rapid device insertion is needed, and modular RF systems where modules are frequently swapped.

How do I handle the connector-to-PCB transition?

The transition from the coaxial connector to the PCB transmission line (microstrip, stripline, CPW) is a critical impedance discontinuity. For best performance: use a connector with an integrated PCB launch pad that matches the PCB's transmission line type. Edge-launch connectors (SMA, 2.92mm): the center pin contacts the microstrip trace at the PCB edge. The ground pins contact the PCB ground plane. The transition should be designed with a tapered ground-signal-ground footprint that maintains 50 ohms through the transition. End-launch connectors provide the best return loss (less than -20 dB to 40 GHz with proper board design).

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