Most GPS Antenna use coaxial cables as downleads, the exceptions being so-called 'Smart' Antennas that have multiple twisted-pair cables.
Because the GPS signal levels are very low, it is often necessary to employ ultra low-loss coaxial cables to avoid attenuation of the signals to unusable levels, particularly for long cable runs.
If the cable run is short (less than 12 metres total)...
It is possible to use RG58 cable for a temporary rig, but this is usually inadequate for permanent use because RG58 is only single shielded and is vulnerable to noise pick-up.
For runs up to about 30metres...
An RG214 has better screening efficiency and lower losses than RG58. RG214 is a 10mm diameter double-shielded type.
For runs of 30 to 70 metres...
Use ultra-low-loss types such as Westflex 103 or Belden 9913. These cables are double-shielded, but have much lower RF losses than RG214. The internal construction is air-spaced, and they have a solid (i.e. non-stranded) inner conductor which means that they are far more vulnerable to damage due to handling. During installation, it is particularly important to avoid sharp bends or accidental kinking to less than the specified minimum-bend-radius, which is about 600mm. This is not a very sharp bend!!
Once a cable has been bent to less than its specified minimum bend radius, straightening it out will not help if it is already damaged internally.
Although they appear to be very strong, all co-axial cables can be damaged by stretching and should not be pulled through long ducts without considerable care. This applies in particular to the very-low-loss types; crushing them with excessively tight cable straps should also be avoided.
Andrew 'Heliax' cable
If necessary, Andrew 'Heliax' cable can be used successfully for GPS receiver applications. This cable is stronger and has lower losses than the types discussed above but it is heavy and as a result, may require more mechanical support along the run. In addition it is larger in diameter, and is relatively expensive.
Many different grades of cable are known by the generic title of 'Heliax'. The most satisfactory type for GPS downleads is LDF4-50, which has sufficiently low losses to allow runs of 100 metres or more with typical Antennas and Receivers. This is a 13mm OD cable, and it can be made up to N-type connectors, although both 'Heliax' and other low-loss cables may require special N-type connectors and special cutting and stripping tools for satisfactory termination.
Most GPS Antenna use coaxial cables as downleads, the exceptions being so-called 'Smart' Antennas that have multiple twisted-pair cables.
Because the GPS signal levels are very low, it is often necessary to employ ultra low-loss coaxial cables to avoid attenuation of the signals to unusable levels, particularly for long cable runs.
If the cable run is short (less than 12 metres total)...
It is possible to use RG58 cable for a temporary rig, but this is usually inadequate for permanent use because RG58 is only single shielded and is vulnerable to noise pick-up.
For runs up to about 30metres...
An RG214 has better screening efficiency and lower losses than RG58. RG214 is a 10mm diameter double-shielded type.
For runs of 30 to 70 metres...
Use ultra-low-loss types such as Westflex 103 or Belden 9913. These cables are double-shielded, but have much lower RF losses than RG214. The internal construction is air-spaced, and they have a solid (i.e. non-stranded) inner conductor which means that they are far more vulnerable to damage due to handling. During installation, it is particularly important to avoid sharp bends or accidental kinking to less than the specified minimum-bend-radius, which is about 600mm. This is not a very sharp bend!!
Once a cable has been bent to less than its specified minimum bend radius, straightening it out will not help if it is already damaged internally.
Although they appear to be very strong, all co-axial cables can be damaged by stretching and should not be pulled through long ducts without considerable care. This applies in particular to the very-low-loss types; crushing them with excessively tight cable straps should also be avoided.
Andrew 'Heliax' cable
If necessary, Andrew 'Heliax' cable can be used successfully for GPS receiver applications. This cable is stronger and has lower losses than the types discussed above but it is heavy and as a result, may require more mechanical support along the run. In addition it is larger in diameter, and is relatively expensive.
Many different grades of cable are known by the generic title of 'Heliax'. The most satisfactory type for GPS downleads is LDF4-50, which has sufficiently low losses to allow runs of 100 metres or more with typical Antennas and Receivers. This is a 13mm OD cable, and it can be made up to N-type connectors, although both 'Heliax' and other low-loss cables may require special N-type connectors and special cutting and stripping tools for satisfactory termination.