Answers to common questions about coaxial cable types, impedance, signal loss, connectors, and how to choose the right coax for CCTV, CATV, satellite, broadcast, and data applications.
Coaxial Cable Basics
What is coaxial cable?
Coaxial cable (coax) is a shielded cable with a central copper or copper-clad conductor surrounded by a dielectric insulator, one or more metallic shields (foil and/or braid), and an outer jacket. The concentric "coaxial" design confines the signal to the space between the center conductor and shield, which reduces electromagnetic interference and signal loss. Coax is used for video, data, RF, and antenna connections across residential, commercial, and industrial applications. See our Coaxial Cable Guide for a complete overview of coax construction and types.
What is the difference between RG6 and RG59?
RG6 has a larger center conductor (18 AWG vs. 20 AWG) and a larger dielectric, which gives it lower signal loss (attenuation) and better performance at higher frequencies. RG6 is the standard for modern CATV, satellite, and broadband installations. RG59 is thinner and more flexible, but its higher attenuation limits it to shorter runs — it is still used for analog CCTV and some legacy video applications. For most new installations, RG6 is the recommended choice.
What is RG11 coaxial cable?
RG11 is a larger-diameter coax (approximately 0.405" OD) with a 14 AWG center conductor. Its larger size provides the lowest attenuation of the common RG-series cables, making it ideal for long trunk runs, main distribution feeds, and backbone cabling where minimizing signal loss over distance is critical. RG11 is stiffer and harder to terminate than RG6, so it is typically used for longer backbone runs rather than drops to individual outlets.
What is the difference between 50-ohm and 75-ohm coax?
The impedance rating refers to the cable's characteristic impedance, which must match the connected equipment. 75-ohm coax (RG6, RG59, RG11) is optimized for minimal signal loss and is the standard for video, CATV, satellite, and broadband. 50-ohm coax (RG8, RG58, LMR-series) is optimized for power handling and is used for two-way radio, cellular, Wi-Fi antennas, and test equipment. Using the wrong impedance creates signal reflections and degrades performance.
What is dual-shield vs. quad-shield coax?
Dual-shield coax has one layer of foil and one layer of braided wire shielding. Quad-shield adds a second foil and second braid layer for improved resistance to radio frequency interference (RFI). Quad-shield RG6 is recommended in environments with high electromagnetic noise — near commercial radio towers, industrial equipment, or dense urban areas. For typical residential CATV and satellite installations, dual-shield RG6 provides adequate shielding at a lower cost.
What is plenum-rated coax cable?
Plenum-rated coax uses a fire-retardant jacket and low-smoke materials approved for installation in air-handling spaces (above drop ceilings and below raised floors used for HVAC air return). Building codes require plenum-rated cable in these spaces to limit smoke and flame spread in a fire. Plenum coax costs more than standard PVC-jacketed (riser or CM-rated) coax but is mandatory where code requires it. See our Plenum vs. Riser Cable Guide for a detailed comparison of fire ratings.
What is direct burial coax cable?
Direct burial coax has a waterproof jacket (typically gel-filled or with a flooding compound) designed to be installed underground without conduit. It resists moisture ingress, UV exposure, and soil chemicals. Direct burial coax is used for underground runs from utility pedestals to buildings, outdoor CCTV camera feeds, and antenna connections. If the cable will be exposed to the ground or continuous moisture, always specify a direct-burial-rated product. See our Direct Burial Cable Guide for burial depth requirements.
Performance & Specifications
What is impedance in coaxial cable?
Impedance is the cable's opposition to alternating current flow, measured in ohms. It is determined by the physical dimensions of the center conductor, dielectric, and shield — not the cable length. Coaxial systems require impedance matching between the cable, connectors, and equipment (typically 50 ohm or 75 ohm). A mismatch causes signal reflections, increased return loss, and degraded performance. Impedance is a fixed characteristic of the cable design and remains essentially constant across its operating frequency range.
What causes signal loss in coaxial cable?
Signal loss (attenuation) in coax comes from three sources: conductor loss (resistance in the center conductor and shield), dielectric loss (energy absorbed by the insulating material), and radiation loss (signal leaking through the shield). Attenuation increases with frequency and cable length. Larger cables (RG11 vs. RG6) have lower loss because the larger conductors have less resistance. Poor connectors, sharp bends, and water ingress also increase signal loss.
How far can I run coax cable before signal loss is a problem?
Maximum run length depends on the cable type, frequency, and acceptable signal level at the receiving end. As a general guideline for 75-ohm video/CATV applications: RG59 is typically limited to 150–200 feet, RG6 to 300–500 feet, and RG11 to 500–1,000+ feet. Actual maximum distance depends on frequency and the required signal level at the receiver. For runs approaching or exceeding these limits, use amplifiers (line amps or distribution amps) or switch to a larger cable type.
What is attenuation and how is it measured?
Attenuation is the reduction in signal strength as it travels through the cable, measured in decibels per 100 feet (dB/100ft) at a given frequency. Lower attenuation means less signal loss. For example, RG6 quad-shield typically has approximately 5.6 dB/100ft attenuation at 1 GHz, while RG11 has approximately 3.6 dB/100ft at the same frequency. Always check the manufacturer's attenuation table at the specific frequency you are working with, since loss varies significantly across the frequency range.
Does coax cable have a maximum frequency rating?
Coax cable does not have a hard frequency cutoff, but attenuation increases with frequency, so there is a practical upper limit where the signal is too weak to be usable. RG6 is commonly rated for use up to 3 GHz, which covers CATV, satellite (up to Ka-band IF), and MoCA. Specialty coax cables designed for broadcast, test equipment, and RF applications can operate well into the multi-GHz range. The usable frequency range depends on cable quality, run length, and the system's signal budget.
Applications
What coax cable do I need for CCTV security cameras?
For modern HD-over-coax systems (HD-TVI, HD-CVI, AHD), use RG59 Siamese cable (RG59 + 18/2 power conductors in a single jacket) for typical runs up to 200 feet without amplification, or RG6 for longer runs. Siamese cable simplifies installation by carrying video and camera power in one pull. For IP camera systems, coax is typically replaced by network cable (Cat5e or Cat6), but analog and HD-over-coax systems still rely on RG59 or RG6.
What coax cable is used for cable TV (CATV)?
RG6 is the industry standard for CATV distribution, from the service entrance to individual outlets. Use quad-shield RG6 for the trunk run from the demarcation point to the splitter, and dual-shield or quad-shield RG6 for home runs to each outlet. RG11 is used for longer main distribution runs in commercial buildings or multi-dwelling units where attenuation must be minimized. All connections should use compression-type F connectors for reliable, weather-resistant terminations.
What coax cable do I need for satellite TV?
Satellite TV requires RG6 rated for the full satellite IF frequency range (950 MHz to 2,150 MHz). The cable must support the higher frequency signals from the LNB (low-noise block downconverter) on the dish. Use quad-shield RG6 for improved shielding and use only compression F connectors rated for satellite frequencies. Each satellite receiver typically requires its own dedicated home run from the dish or multiswitch — splitters designed for satellite frequencies are different from standard CATV splitters.
What coax cable is used for two-way radio and ham radio?
Two-way radio and amateur (ham) radio systems use 50-ohm coax to match the impedance of most RF transmitters and antennas. Common choices include RG8/U and RG213 for HF through VHF frequencies, LMR-400 for VHF/UHF base stations and repeaters, and RG58 for short patch cables and mobile installations. The key selection factors are frequency range, transmit power, and run length — higher power and longer runs require larger, lower-loss cable.
Can coax cable carry internet?
Yes. Cable internet (DOCSIS) uses the same RG6 coaxial infrastructure as CATV to deliver broadband service. MoCA (Multimedia over Coax Alliance) technology also uses existing coax wiring to distribute Ethernet-speed networking within a building. In both cases, RG6 is the recommended cable. Coax does not replace dedicated Ethernet (Cat5e/Cat6) for device connections, but it is an effective way to extend network connectivity through existing coax wiring.
What coax is used in broadcast and professional AV?
Broadcast and professional AV applications use precision 75-ohm coax designed for SDI (Serial Digital Interface) video. Common types include miniature coax for HD-SDI patch cables and larger coax for 12G-SDI trunk runs supporting 4K video. These cables have tighter impedance tolerances and lower return loss than standard CATV coax. For analog video, standard RG59 or RG6 with BNC connectors is used. The specific cable grade depends on the SDI data rate and run length required.
Installation
Can coax cable be run next to electrical power cables?
It is best practice to maintain separation between coax and power cables to minimize electromagnetic interference. TIA and industry best practices recommend a minimum of 12 inches of separation from unshielded power cables, or 6 inches if the power cable is in a grounded metal conduit. If coax must cross power cables, cross at a 90-degree angle to minimize coupling. Using quad-shield coax improves rejection of interference from nearby power lines.
What connectors are used with coaxial cable?
The most common connectors are F-type (used for CATV, satellite, and broadband), BNC (used for CCTV, broadcast SDI, and test equipment), and N-type (used for 50-ohm RF and antenna connections). Compression connectors are strongly recommended over crimp or push-on types because they provide a more reliable, weather-resistant connection with lower signal loss. Always match the connector to the specific cable type (e.g., RG6 F-compression connectors are sized differently than RG59 F-compression connectors).
What is the maximum bend radius for coaxial cable?
The general rule is a minimum bend radius of 10 times the cable's outer diameter. For RG6 (approximately 0.270" OD), that is about 2.7 inches; for RG11 (approximately 0.405" OD), about 4 inches. Exceeding the bend radius can deform the dielectric, shift the center conductor off-axis, and change the cable's impedance at the bend point — causing signal reflections and increased attenuation. Avoid sharp bends at wall plates, J-hooks, and cable tray transitions.
Can I splice coax cable?
Yes, but every splice introduces signal loss and a potential point of failure. Use a barrel connector (F-type or BNC, depending on the application) with compression fittings on both cable ends. Each splice typically adds 0.5–1.0 dB of loss. For critical runs, a continuous cable with no splices is always preferred. If you must splice, use high-quality connectors and weatherproof the joint for outdoor or direct-burial applications.
Can coax cable be installed outdoors?
Yes, but use cable rated for outdoor exposure. Standard PVC-jacketed coax will degrade under prolonged UV exposure. Look for cables with a UV-resistant (typically black) PE jacket or cables specifically rated for outdoor/direct burial use. For underground runs, use direct-burial-rated coax or install standard coax inside weatherproof conduit. Outdoor F-connectors should be compression-type and sealed with weatherproof boots or silicone tape.
Buying Coax Cable from Ramcorp
Can I buy coax cable by the foot?
We sell coaxial cables with low minimums, and some types are available by the foot. Availability depends on the specific cable type and jacket rating. For larger jobs, we can supply full manufacturer reels at volume pricing. Contact our sales team to confirm cut-to-length availability for the coax you need.
What types of coax cable does Ramcorp stock?
We stock RG6, RG59, RG11, and specialty coaxial cables in plenum, riser, direct burial, and outdoor-rated jackets from major U.S. manufacturers. We also carry Siamese CCTV cable (RG59 + power) and bulk spool options. If you need a specific type or rating not shown in our catalog, contact our sales team and we'll confirm availability.
Do you ship coax cable internationally?
Yes. We ship wire and cable to businesses in countries permitted by U.S. export laws. Most coaxial cable is classified EAR99, which allows export to most destinations without a license. See our International Orders & Shipping page and EAR99 Export Guide for details on export documentation and compliance.
Have a question not answered here? Contact our sales team — we respond within one business day.
Disclaimer: This information is for general reference only. Always consult a qualified installer and follow applicable codes and manufacturer specifications for your installation.