Intro

There are very wide variety of RF connector and even more developed and added every year. RF are usually used to make low VSWR coaxial connections. Most RF and high-frequency systems use 50 Ω characteristic impedance, but some other values, such as 75 ohms used as well. All RF connectors described below have specified impedance, frequency range and size listed.

Few notes on precision RF connectors usage

While some of connectors, like SMA, 3.5mm, 2.92mm, 2.4mm are mechanically and physically compatible, there is hidden cost, in impedance mismatching and impedance consistency. This means that amplitude accuracy and signal waveform repeatability of mismatched connector path would be reduced. Millimeter-wave signals can’t be transmitted without having loss and phase errors.

Even simple connector savers, which are essentially feed-thru adapters, usually a good practice working with RF expensive equipment, also degrade signal integrity due to differences in mechanical interfaces. One of the solutions is simply to have cable attached to instrument at all times, so connectors would not see frequent connection cycles. It’s important to also consider cable length and cable quality carefully, especially for frequencies over 3 GHz. Quality cables can be expensive but may be the required item to ensure measurements accuracy and repeatability.

Coaxial connectors – overview

Type / name	Frequency range	Impedance, Ω	Dielectric	Year	Description
BNC	DC – 4 GHz	50	PTFE
SMA	DC – 26 GHz	50/75	PTFE	1960’s	Sub-miniature type A, threaded
SMB	DC – 4 GHz	50	PTFE		Sub-miniature type B, a snap-on subminiature connector
SMC	DC – 10 GHz	50	PTFE		Sub-miniature type C, a threaded subminiature connector
SSMA	DC – 38 GHz	50	PTFE		Smaller version of SMA
N (Neill)	DC – 11 GHz (18GHz)	50/75	PTFE	1940’s	Named for Paul Neill of Bell Labs. Cheap and heavy-duty
BMA or OSP	DC – 22 GHz	50	PTFE		“Omni Spectra push-on”, blind-mate connector with zero detent
C (Concelman)	DC –
Dezifix (used by Rohde & Schwarz)	DC –
F	DC –	75
GR
Musa
OSX, MCX , PCX	DC – 6 GHz	50/75	PTFE
MMCX		50	PTFE		Usual for wireless industry due to small size and cost
NMO
NMD from HP, 3.5mm	DC to 34 GHz				Used by HP/Agilent/Keysight RF gear
NMD from HP, 2.92mm	DC to 40 GHz				Used by HP/Agilent/Keysight RF gear
NMD from HP, 2.4mm	DC to 50 GHz				Used by HP/Agilent/Keysight RF gear
NMD from HP, 1.85mm	DC to 70 GHz				Used by HP/Agilent/Keysight RF gear
NMD from HP, 1.0mm	DC to 110 GHz				Used by HP/Agilent/Keysight RF gear
OSMT	DC – 6 GHz	50	PTFE		SMT connector
OSSP	DC – 28 GHz	50	PTFE		Smaller version OSP connector
OS-50P	DC – 40 GHz	50			Smaller version OSP blind-mate connector
GPO, OSMP , SMP	DC – 40 GHz	50	PTFE		“Gilbert push-on”
TNC	DC – 15 GHz	50	PTFE		Threaded BNC, to reduce vibration issues
APC , 7 mm	DC – 18 GHz	50	PTFE	1960’s	Sexless connector, which provides the lowest VSWR up to 18 GHz
3.5 mm	DC – 26.5 GHz	50	Air		A precision (expensive) connector, compatible with SMA connectors
2.92 mm	DC – 40 GHz	50	Air	1974	Precision connector, compatible with SMA and 3.5 mm
K	DC – 40 GHz	50	Air	1974	Mass-marketed 2.92 mm connector, Named the “K” connector, as it covers all K frequency bands
2.4 mm	DC – 50 GHz	50	Air	1986	2.4 mm and 1.85 mm will mate with each other without damage
1.85 mm	DC – 60 GHz	50	Air	1986	Mechanically compatible with 2.4 mm
V	DC – 60 GHz	50	Air	1986	Anritsu’s name for 1.85 mm connectors, as it span V frequency bands
1.35 mm	DC – 90 GHz	50	Air		mmWave connector type
1 mm	DC – 110 GHz	50	Air	1989	mmWave connector type
0.8 mm	DC – 145 GHz	50	Air	2019	Anritsu mmWave connector type
0.6 mm	DC – 220 GHz	50	Air	2020	Anritsu mmWave connector type

Even though some connector combinations like SMA and 2.92mm connectors are thread-compatible, plugging one into the other can damage the sleeve in the receptacle side due to differences in the diameter tolerance. So it can be OK to plug a 2.92mm plug into an SMA jack, but NOT OK to put an SMA plug into a 2.92mm jack. The jacks are usually more fragile port of connection.

SMA connector system

The SMA connector is very common in the RF and microwave industry. Design uses a 4.2 mm diameter outer coax, filled with PTFE dielectric. Upper frequency limit is anywhere from 18 to 26 GHz, depending on the tolerances maintained in machining SMA connectors. Outer nut sized to fit a 5/16” wrench. These connectors have male and female genders.

Lot of SMA connectors are gold-plated, but it is not always best, as thin gold plating can chip off and cause shorts and problems. The best connectors usually with stainless steel on their outer jackets.

SMB and SMC connector systems

http://www.microwaves101.com/encyclopedias/smb-connectors

High-frequency connectors

NEVER rotate these connectors when tightening. Use a 8 inch/lb torque wrench and a smaller wrench to hold the other connector during mating.

Never, ever connect a SMA to a 3.5 or 2.92 mm ports, VNA cables, or any other expensive 3.5 mm device. Use the jack savers, which are adapters with SMA on one side and 3.5/2.92mm on other.

3.5 mm type

This type connector using air dielectric, meaning central conductor is hold in center by spacers only. The 3.5 mm connector is the next upgrade from using SMA, it performs well up to 26 GHz. Outer nut sized to fit a 5/16” wrench.

2.92 mm type

The 2.92 mm connector works up to 40 GHz. The K is Anritsu version of the 2.92 mm connector. Outer nut sized to fit a 5/16” wrench.

2.4 mm type

Outer nut sized to fit a 5/16” wrench.

1.85 mm type

The 1.85 connector is often referenced as V type. Outer nut sized to fit a 5/16” wrench.

1 mm type

This is highest frequency coax connector. Requirements for it’s precision can drive cost of single 1 mm connector over $1000 USD!

NMD versions of connectors

NMD connectors are rugged version of same standard geometry connector, such as 3.5mm, 2.4mm and such. Usually these connectors used on GHz-frequency network analyzers, signal generators, oscilloscopes. Few examples covered in this blog post by Keysight.

Coax cable types

Cable Type	Mil Designation	Impedance, Ω	Dielectric	OD (Inches)	Shield Construction
RG-87		50	PTFE	0.425	Braid
RG-141		50	ST	0.190	Braid
RG-174		50	PE	0.100	Braid
RG-122	/54 -RG122	50	PE	0.160	Braid
RG-178	/93 -RG178	50	ST	0.072	Braid
RG-142	/60 -RG142	50	ST	0.195	Braid
RG-188		50	PTFE	0.105	Braid
RG-188 Double Braided		50	PTFE	0.105	Double Braid
RG-196		50	PTFE	0.072	Braid
RG-303	/111-RG303	50	ST	0.170	Braid
RG-213	/74 -RG213	50	PE	0.405	Braid
RG-214	/75 -RG214	50	PE	0.425	Braid
RG-223	/84 -RG223	50	PE	0.211	Double Braid
RG-225		50	PTFE	0.430	Braid
RG-304	/112-RG304	50	ST	0.280	Braid
RG-316	/113-RG316	50	ST	0.102	Braid
RG-316 Double Braided		50	ST	0.102	Double Braid
RG-393	/127-RG393	50	ST	0.390	Braid
RG-400	/128-RG400	50	ST	0.195	Braid
RG-9		51	PE	0.420	Braid
RG-8		52	PE	0.405	Braid
RG-55		53.5	PE	0.200	Braid
RG-58	/28 -RG58	53.5	PE	0.195	Braid
RG-179	/94 -RG179	70	ST	0.100	Braid
RG-59	/29 -RG59	73	PE	0.242	Braid
RG-140		75	PTFE	0.233	Braid
RG-179 Double Braided		75	ST	0.125	Double Braid
RG-187		75	PTFE	0.105	Braid
RG-302	/110-RG302	75	ST	0.201	Braid
RG-62		93	PE	0.242	Braid
RG-180	/95 -RG180	93	ST	0.140	Braid
RG-210		93	PTFE	0.242	Braid
RG-195		95	PTFE	0.450	Braid

Waveguides – overview

Most of waveguides are made to order, with various shapes and lengths featuring precision machining from solid alloy, often with gold plated finish and a choice of flanges.

WG type

WG DESIGN	FREQ RANGE, NOTE WAVEGUIDE CUT OFF	Attenuation dB/30m	Material	Band	DIMENSIONS,mm
WG00	0.32 – 0.49 GHz	0.256 GHz	0.051 – 0.031	Alum	B	584 × 292
WG0	0.35 – 0.53 GHz	0.281 GHz	0.054 – 0.034	Alum	B,C	533 × 267
WG1	0.41 – 0.625 GHz	0.328 GHz	0.056 – 0.038	Alum	B,C	457 × 229
WG2	0.49 – 0.75 GHz	0.393 GHz	0.069 – 0.050	Alum	C	381 × 191
WG3	0.64 – 0.96 GHz	0.513 GHz	0.128 – 0.075	Alum	C	292 × 146
WG4	0.75 – 1.12 GHz	0.605 GHz	0.137 – 0.095	Alum	C,D	248 × 124
WG5	0.96 – 1.45 GHz	0.766 GHz	0.201 – 0.136	Alum	D	196 × 98
WG6	1.12 – 1.70 GHz	0.908 GHz	0.317 – 0.212	Brass	D	165 × 83
WG6	1.12 – 1.70 GHz	0.908 GHz	0.269 – 0.178	Alum	D	165 × 83
WG7	1.45 – 2.20 GHz	1.157 GHz			D,E	131 × 65
WG8	1.70 – 2.60 GHz	1.372 GHz	0.588 – 0.385	Brass	E	109 × 55
WG8	1.70 – 2.60 GHz	1.372 GHz	0.501 – 0.330	Alum	E	109 × 55
WG9A	2.20 – 3.30 GHz	1.736 GHz	0.877 – 0.572	Brass	E,F	86 × 43
WG9A	2.20 – 3.30 GHz	1.736 GHz	0.751 – 0.492	Alum	E,F	86 × 43
WG10	2.60 – 3.95 GHz	2.078 GHz	1.102 – 0.752	Brass	E,F	72 × 34
WG10	2.60 – 3.95 GHz	2.078 GHz	0.940 – 0.641	Alum	E,F	72 × 34
WG11A	3.30 – 4.90 GHz	2.577 GHz			F,G	59 × 29
WG12	3.95 – 5.85 GHz	3.152 GHz	2.08 – 1.44	Brass	F,G	48 × 22
WG12	3.95 – 5.85 GHz	3.152 GHz	1.77 – 1.12	Alum	F,G	48 × 22
WG13	4.90 – 7.05 GHz	3.711 GHz			G,H	40 × 20
WG14	5.85 – 8.20 GHz	4.301 GHz	2.87 – 2.30	Brass	H	35 × 16
WG14	5.85 – 8.20 GHz	4.301 GHz	2.45 – 1.94	Alum	H	35 × 16
WG15	7.05 – 10.0 GHz	5.26 GHz	4.12 – 3.21	Brass	I	29 × 13
WG15	7.05 – 10.0 GHz	5.26 GHz	3.50 – 2.74	Alum	I	29 × 13

WR type

WR DESIGN	WG EQUIVALENT	Freq range	Band	Standard Flange	Inner DIMENSIONS (inch)
WR340	WG9A	2.20 – 3.30 GHz	D		3.400 × 1.700
WR284	WG10	2.60 – 3.95 GHz	S		2.840 × 1.340
WR229	WG11A	3.30 – 4.90 GHz	E		2.290 × 1.150
WR187	WG12	3.95 – 5.85 GHz	G		1.872 × 0.872
WR159	WG13	4.90 – 7.05 GHz	F		1.590 × 0.795
WR137	WG14	5.85 – 8.20 GHz	C		1.372 × 0.622
WR112	WG15	7.05 – 10.00 GHz	H		1.122 × 0.497
WR90	WG16	8.2 – 12.4 GHz	X		0.900 × 0.400
WR75	WG17	10.0 – 15.0 GHz	X-Ku		0.750 × 0.375
WR62	WG18	12.4 – 18.0 GHz	Ku		0.622 × 0.311
WR51	WG19	15.0 – 22.0 GHz	K		0.510 × 0.255
WR42	WG20	18.0 – 26.5 GHz	K		0.420 × 0.170
WR28	WG22	26.5 – 40.0 GHz	Ka	UG 599/U	0.280 × 0.140
WR22	WG23	33 – 50 GHz	Q	UG 383/U	0.224 × 0.112
WR19	WG24	40 – 60 GHz	U	UG 383/U	0.188 × 0.094
WR15	WG25	50 – 75 GHz	V	UG 385/U	0.148 × 0.074
WR12	WG26	60 – 90 GHz	E	UG 387/U	0.122 × 0.061
WR10		75 – 110 GHz	W	UG 387/U-M	0.100 × 0.050
WR8		90 – 140 GHz	F	UG 387/U-M	0.080 × 0.040
WR6		110 – 170 GHz	D	UG 387/U-M	0.065 × 0.0325
WR5		140 – 220 GHz	G	UG 387/U-M	0.051 × 0.0255
WR4		170 – 260 GHz		UG 387/U-M	0.043 × 0.0215
WR3		220 – 330 GHz		UG 387/U-M	0.034 × 0.0170
WR2		325 – 500 GHz	Y	UG 387/U-M	0.020 × 0.0100
WR1.5		500 – 750 GHz		UG 387/U-M	0.015 × 0.0075
WR1		750 – 1100 GHz		UG 387/U-M	0.010 × 0.0050

http://www.everythingrf.com/tech-resources/waveguides-sizes