Coax Information

With this basic information on coax cables, we hope that you can make a more informed choice when purchasing.

Coaxial Definition:

1. Having or being mounted on a common axis (Mathematics)
2. Having all the centers on a straight line (Geometry of a set of circles)
3. Consisting of two concentric conductors separated by an insulator. (Of a cable or line)

What that means in the real world is that coaxial cable consists of a center conductor, a layer of insulation around it, and a second conductor wrapped entirely around the insulation with a top insulation layer (Figure 1). The center conductor carries the signal, and the outer conductor is used as the shield/ground/signal return path.

Figure 1

Technically, most unbalanced cables and instrument cables are coaxial cables, but for most applications, when the term coaxial cable is used, it is referencing a cable that is designed for transmission of RF data, like video or digital audio. These coaxial cables (coax) are made with very specific properties to handle the high-frequency signal properly.

Main properties of coax:

• Characteristic impedance
• Attenuation
• Bandwidth
• Shielding

Characteristic impedance is probably the most important aspect of the cable and the hardest to grasp, and the full details are beyond the scope of this page. Even a simple definition is hard to come by, so we'll explain it like this:

Characteristic impedance is a relationship between the center conductor and the shield affected by the diameter of the center conductor, the spacing between conductors, and the type of plastics used. It has no relation to the length of the cable. The most common impedances for coax are 75 ohms and 50 ohms. For proper transmission, the full chain must maintain the proper impedance; for example, a video signal must start with a 75ohm output to a 75ohm BNC to a 75ohm coax to a 75ohm BNC into a 75ohm input. When you have an impedance mismatch, it will cause a reflection of signal power back down the cable, and this reflection will mix with the original signal causing loss and signal error. In a way, it can be compared to a water pipe: if the pipe is straight and smooth, the water flows great, but if you smash a section of pipe, the water does not flow as smoothly. Generally, you don't need to know a lot about impedance - as long as you maintain it, you will be good.

Attenuation simply defines the amount of loss the cable will have over a distance and is dependent on frequency. The higher the frequency, the more attenuation you will have. This is more important on long runs; a high-loss cable might be fine for 1 foot, but that same cable might lose your entire signal at 200 feet. Generally, you want to pick a cable for the lowest loss possible, but sometimes other factors play into this, like size, weight, flexibility, etc. As a general rule, a thicker gauge will have less loss, a stranded center (core) conductor will have a greater loss than a solid core, and a solid copper core will have less loss than a copper-clad steel core.

Bandwidth defines the maximum frequencies for which the cable is specified at a specific length. Sometimes this information can be hard to find, or they will just give you a maximum frequency on an attenuation cart. At short lengths, cables are very forgiving; you can probably run 3G HD-SDI (video signal) down just about any cable for a foot or two, but if you want to be certain it will work, you need to pick a cable with the proper bandwidth. As a general rule, a cable that has a higher bandwidth will have a better shield.

Shielding is how the shield is constructed. Shield options are foil, braid, and wrapped. A common type for RG6 will be 60% braid - 100% foil; this is a dual shield. You can find shields in almost any configuration, depending on the application. Shields can be a single layer or up to four layers. The foil will shield better at high-frequencies but often makes for a stiffer cable. Braid is commonly paired with foil; with a single braided shield, it is impossible to get 100% coverage. Wrapped shields in coax are not very common, probably because as the cable flexes, it can open gaps in the shield. Interestingly, the coax shield in an RF application is used as much to keep the signal in as it is to keep interference out.

The 75ohm coax cable is used for a broad range of applications, including (typical maximum bandwidth required):

• SDI (360 MHz)
• HD SDI (1.5 GHz)
• 3G SDI (3 GHz)
• Composite (75 MHz)
• Component (75 MHz)
• Word Clock (192 kHz)
• MADI (AES10) (125 MHz)
• SPDIF (6 MHz)
• AM (30 MHz)
• FM (108 MHz)
• VHF (300 MHz)
• UHF (3 GHz)
• Cable TV (1 GHz)
• more...

The 50ohm coax cable is used for many things, but not as many in our main market. Those applications include:

• Antennas
• Wireless Mic Antennas
• Wireless Monitor Antennas
• more...

Generally, high-frequency coax cables are classified under the "RG" system; for example: RG-6, RG-59, RG-11, RG-58, and many more. This just gives you a starting point - you can find many versions of each of these cables. For example, RG-6/U you can get in:

• 18AWG copper-clad steel with 100% foil/60% aluminum braid
• 18AWG copper with 100% foil/95% copper braid
• 18AWG copper with 100% foil/ 30ga served shield
• 18AWG copper-clad steel with 100% foil/95% aluminum braid

And that is just one page of one of my catalogs. The only consistency is the 18ga size of the center conductor.

Even though there may be a great many flavors of one specific cable, the "RG" number can get you in the ballpark, but further scrutiny of the specs should be done.

At Event Horizon & Services, we stock the cables that best serve the most applications in our market. Here is a list with links to the products for quick reference. If you have a specific need, please let us know, and we'll see how we can help you.

RapcoHorizon COAX-59T

the RapcoHorizon COAX-59T is a medium-weight, coax, 75-ohm style cable that is very flexible, and durable, with great performance. It will fill your needs for medium-abuse environments.

The COAX-59T wire has a 24AWG stranded center conductor with a 95% braided shield, and a black jacket. It is an RG-59B/U style cable with 1 GHz bandwidth with an attenuation of 12.8 dB at 1 GHz for 100ft.

Carol RG-6U

The Carol RG-6U C5775 is a medium-weight, coax, 75-ohm style cable that is moderately flexible, and durable, with great performance. It will fill your needs for low abuse environments, best for studio or installed applications.

The RG-6U wire has an 18AWG center conductor and dual shields 100% foil and 60% braided shield, and a black jacket. It is an RG-6/U style cable with 3 GHz bandwidth with an attenuation of 11.79 dB at 3 GHz for 100ft.

Gepco VE61859M

The Gepco VE61859M is a medium-weight, coax, 75-ohm style cable that is very flexible, and durable, and offers great performance. It will fill your needs for medium/high abuse environments, best for studio, live, or installed applications.

The VE61859M wire has a 22AWG stranded center conductor and a 95% braided shield, and a black jacket. It is an RG-59 style cable with 1 GHz bandwidth with an attenuation of 10.64 dB at 1 GHz for 100Ft.

Gepco VHD1100

The Gepco VHD1100 is a heavy-weight, coax, 75-ohm style cable that is moderately flexible, and durable, and offers great performance with very low attenuation. It will fill your needs for medium abuse environments, best for studio or installed applications.

The VHD1100 wire has a 14AWG solid center conductor and dual shields, 95% braided and 100% foil shields, and a black jacket. It is an RG-11 HD style cable with 4.5 GHz bandwidth with an attenuation of 8.75 dB at 4.5 GHz for 100Ft.

Gepco VHD2000M

The Gepco VHD2000M is a medium-weight, coax, 75-ohm style cable that is very flexible, and durable, and offers great performance. It will fill your needs for medium/high abuse environments, best for studio, live, or installed applications.

The VHD2000M wire has a 21AWG stranded center conductor and dual 95% braided shields, and a black jacket. It is an RG-59 HD style cable with 3 GHz bandwidth with an attenuation of 19.60 dB at 3 GHz for 100Ft.

Belden 1694F

The Belden 1694F is a medium-weight, coax, 75-ohm style cable that is very flexible and durable and offers great performance with low attenuation. It will fill your needs for medium/high abuse environments, best for studio, live, or installed applications.

The 1694Fwire has a 19AWG stranded center conductor and dual 95% braided shields, and a black jacket. It is an RG-6 HD style cable with 6 GHz bandwidth with an attenuation of 28.7 dB at 6 GHz for 100Ft.

Belden 1505F

The Belden 1505F wire is a medium-weight, coax 75-ohm style cable that is very flexible, durable, and offers great performance with low attenuation. It will fill your needs for medium/high abuse environments, best for studio, live, or installed applications.

The 1505F wire has a 22AWG stranded center conductor and dual 95% braided shields, and a black jacket. It is an RG-59 HD style cable with 6 GHz bandwidth and an attenuation of 32.2 dB at 6 GHz for 100ft.

Clark CD7506

The Clark Wire CD7506 is a medium-weight, coax, 75-ohm style cable that is moderately flexible, and durable, and offers great performance with low attenuation. It will fill your needs for medium abuse environments, best for studio or installed applications.

CD7506 wire has 18AWG solid center conductor and dual shields, 95% braided and 100% foil shields, and a black jacket. It is an RG-6 HD style cable with 4.5 GHz bandwidth with an attenuation of 13.3 dB at 4.5 GHz for 100Ft.

Mogami 2964

The Mogami W2964 is a medium-weight, coax, 75-ohm style cable that is very flexible, and durable, and sounds great. It will fill your needs for high-abuse environments.

The 2964 wire has a 24AWG center conductor, dual served shields, and a gloss black jacket. This does not conform to a standard RG cable size, Mogami provides specifications to 10 MHz with attenuation of 1.9 dB at 10 MHz for 100ft. According to the Mogami reps, it will support 3G SDI at a maximum of about 100ft, but for optimal performance, the maximum is at 50ft.

To simplify the chart, some of the values have been interpreted from known values.

( 1 GHz = 1000 MHz)