Coaxial cable is one of the most important parts of any RF, antenna, or communication system. Whether you’re working on a vehicle antenna, a radio setup, or a fixed installation, choosing the right coax cable can make a major difference in signal strength and performance.
The challenge is that there are many different types—RG58, RG8, LMR-240, LMR-400, and more—and they are often confused or used incorrectly.
This guide breaks down the most common coax cable types and explains how to choose the right one for your application.
What is Coax Cable?
Coaxial cable (or “coax”) is a type of cable designed to carry high-frequency electrical signals with minimal interference.
It has four main parts:
- A central conductor (carries the signal)
- A dielectric insulator
- A braided or foil shield (blocks interference)
- An outer jacket (protects the cable)
The key advantage of coax is its ability to maintain signal integrity over distance while resisting noise.
Common Coax Cable Types
RG58 Coax Cable
RG58 is one of the most widely used general-purpose coax cables.
Typical characteristics:
- Thin and flexible
- 50-ohm impedance
- Best for short runs (under ~20–25 feet)
- Higher signal loss over long distances
Best for:
- Short antenna connections
- Basic radio setups
- Compact installations where flexibility matters
Limitation:
Signal loss increases quickly as distance grows, especially at higher frequencies.
RG8 Coax Cable
RG8 is a thicker, heavier-duty coax cable compared to RG58.
Typical characteristics:
- Lower signal loss than RG58
- Thicker and less flexible
- Better for longer runs
- 50-ohm impedance
Best for:
- Medium-length antenna runs
- Base stations
- Higher power RF applications
Limitation:
Less flexible and harder to route in tight spaces.
LMR Series Coax (LMR-240, LMR-400, etc.)
LMR cables are modern low-loss coax cables designed for better performance.
LMR-240
- Medium flexibility
- Low to moderate loss
- Good for medium distances
LMR-400
- Very low signal loss
- Excellent performance over long distances
- Thicker but still manageable
Best for:
- Professional RF systems
- Long cable runs
- High-frequency applications
- Outdoor antenna installations
Why LMR is popular:
It provides significantly lower loss compared to RG cables, especially at higher frequencies.
Key Factor: Signal Loss (Attenuation)
All coax cables lose signal strength over distance. The key difference between cable types is how fast that loss happens.
- Thinner cables = higher loss
- Thicker cables = lower loss
- Higher frequencies = more loss
This is why cable choice matters more as frequency or distance increases.
How to Choose the Right Coax Cable
Here’s a simple way to decide:
1. Cable Length
- Under 20 ft → RG58 is usually fine
- 20–50 ft → RG8 or LMR-240
- 50+ ft → LMR-400 recommended
2. Frequency
Higher frequencies (like UHF or microwave ranges) require lower-loss cable such as LMR series.
3. Power Level
Higher transmit power benefits from thicker cables that can handle heat and reduce loss.
4. Installation Environment
- Tight spaces → RG58
- Permanent outdoor installs → LMR-400
- Mobile setups → flexible RG or LMR-240
RG vs LMR: The Real Difference
LMR cables are modern low-loss coax cables designed for better performance.
LMR-240
- Medium flexibility
- Low to moderate loss
- Good for medium distances
LMR-400
- Very low signal loss
- Excellent performance over long distances
- Thicker but still manageable
Best for:
- Professional RF systems
- Long cable runs
- High-frequency applications
- Outdoor antenna installations
Why LMR is popular:
It provides significantly lower loss compared to RG cables, especially at higher frequencies.
Key Factor: Signal Loss (Attenuation)
All coax cables lose signal strength over distance. The key difference between cable types is how fast that loss happens.
- Thinner cables = higher loss
- Thicker cables = lower loss
- Higher frequencies = more loss
This is why cable choice matters more as frequency or distance increases.