RG316 VS RG174: Which Coaxial Cable Is Suitable for You?

We will talk about two common coaxial cables and why they should be used. The RG coaxial cable is an old term meaning “Radio Grade” The U means Universal and dates back to the MIL-HDBK-216 published in the early 1960’s. The commercial version would be RG-174U and the quality would be subject to the specific coaxial cable manufacturer. Certain brand name manufacturers make an excellent version of the RG-174U they are also the ones making the military version most likely on the same production line.  The Military Version would be M17/173-00001 which is QPL and certified to meet the specifications of MIL-C-17 which is the current Military Standard. The manufacturer must have the production line certified by the US Government to meet those requirements. 

The critical question is what frequency the cable is to be used for.

When choosing a cable, the 1st question one should ask is what frequency is the signal that I am trying to send over the cable? Is the signal digital or analogue? Digital signals are summations of sine waves with the highest frequency ones giving the digital square wave its edges. If the system is sensitive to sharp edges or fast rise times this should be taken into account. We have found a general formula to use: is three times the clock speed for a digital signal. For a high-performance digital signal use 5-7 times the clock speed.

For example: if the clock speed is 1 GHz use a minimum of 3 GHz to 7 GHz for the transmission line. The reason for this is the high frequency signals are attenuated to a greater extent within the transmission line. This causes rounding of the signal and a loss of the sharp edges.

The following chart details the technical similarities and differences between RG174 and RG316.

COMPARISON THE TECHNICAL DATA – COAXIAL CABLE RG174 vs RG316

Here you can see at first sight the characteristics of each coaxial cable, possibly from different manufacturers.

		Cable A		Cable B
Description		RG174 Coaxial cable		RG316 Coaxial cable
Addition		D= 2,80 mm / PVC / Temp: -30°C bis +70 °C		D= 2,54 mm / FEP / Temp: -100°C bis +200°C
Impedance	[Ω]	50		50
Capacity	[pF/m]	100		95
Sheath material	[mm/Ø]	2.8		2.54
Material		PVC		FEP
Color		black		brown
Inner conductor	[mm/Ø]	0.5		0.9
Material		Steel copper strand		Copper stranded wire silver-plated
Frequency	[max/GHz]	1		1
Max. Voltage	[V]
Cable attenuation	[db/400MHz]	0.55		0.53
	[db/1GHz]	0.88		0.93
	[db/2GHz]
Shield 1		Tinned copper braid		Silver-plated copper braid
Insulation		PE		PTFE
Shielding factor	[db]	52
Velocity	[%/c]	66		69
Delay	[ns/m]
Mechanical
Temperature	max. [°C]	+70		+200
	min. [°C]	-30		-100
Bending radius	single [mm]	14		13
Weight	[kg/m]	0.012		0.015
Halogen-free
Trailing cable
No Magnetic

Legend:

Compare selection cable A with selection cable B

The following characters are:

	:	for this property cable B is more suitable than cable A
	:	for this property cable B is less suitable than cable A
	:	cable B is equal to cable A

So, which one is best? They both are applicable in LAN/WAN or GPS. They both have a small diameter, are flexible, and both have a higher signal loss than larger diameter cables. The main differences are that RG316 coax has a far lower and higher temperature tolerance due to its FEP outer jacket, which may be reflected in the higher price of RG316.

The above table details the technical differences and similarities between RG174 and RG316. Your decision needs to be based mainly on frequency required (details in the introduction) and temperature tolerance required.