Project Bases

[mmartin798]

Originally Posted by dragoon500ly

The main radio associated with these stations is the AN/PRC-70 which is listed as having a 4,000km with the AS-2975 antenna for CW only. Range for SSB and AM is up to 800 kilometres, range for FM is 40 kilometres.

One thing to remember about these ranges is that they are for two specific antennas, one a rod (monopole) and the other a dipole. Nothing prevents the use of a properly tuned directional antenna, like a yagi antenna, to extent the range of repeaters well beyond those ranges. The biggest difference is that the monopole and dipole antenna have radiation patterns that work much better for broadcast than the highly directional nature of a yagi.

If the intent of the repeater is to facilitate point to point communications, the yagi would be the way to go. If they send and receive to a large area around the ground station, you would use a monopole or dipole antenna. Not having the module to read the intended use for the repeaters, I cannot say with any certainty what the spacing of repeaters would be. It is possible that they place different antennas at the repeaters to increase coverage while minimizing number of bases. For instance, there may be a number of stations that use dipole antennas that are wider spaced with a large, but acceptable, marginal signal strength that are interconnected via a network of directional repeaters. This would allow the directional repeaters to operate a lower power and therefore be smaller than the broadcast bases.

[cosmicfish]

Originally Posted by mmartin798

One thing to remember about these ranges is that they are for two specific antennas, one a rod (monopole) and the other a dipole. Nothing prevents the use of a properly tuned directional antenna, like a yagi antenna, to extent the range of repeaters well beyond those ranges. The biggest difference is that the monopole and dipole antenna have radiation patterns that work much better for broadcast than the highly directional nature of a yagi.

If the intent of the repeater is to facilitate point to point communications, the yagi would be the way to go. If they send and receive to a large area around the ground station, you would use a monopole or dipole antenna. Not having the module to read the intended use for the repeaters, I cannot say with any certainty what the spacing of repeaters would be. It is possible that they place different antennas at the repeaters to increase coverage while minimizing number of bases. For instance, there may be a number of stations that use dipole antennas that are wider spaced with a large, but acceptable, marginal signal strength that are interconnected via a network of directional repeaters. This would allow the directional repeaters to operate a lower power and therefore be smaller than the broadcast bases.

You can also use multiple antennas on the same system - perhaps use directional antennas like yagis or dishes to connect to specific distant locations while using a dipole or monopole to broadcast or receive locally. Personally, I would expect this architecture to be a staple of team communications - put monopole on the hull serve as a hub for team communications, use a directional to connect to higher command.

[dragoon500ly]

Originally Posted by mmartin798

One thing to remember about these ranges is that they are for two specific antennas, one a rod (monopole) and the other a dipole. Nothing prevents the use of a properly tuned directional antenna, like a yagi antenna, to extent the range of repeaters well beyond those ranges. The biggest difference is that the monopole and dipole antenna have radiation patterns that work much better for broadcast than the highly directional nature of a yagi.

If the intent of the repeater is to facilitate point to point communications, the yagi would be the way to go. If they send and receive to a large area around the ground station, you would use a monopole or dipole antenna. Not having the module to read the intended use for the repeaters, I cannot say with any certainty what the spacing of repeaters would be. It is possible that they place different antennas at the repeaters to increase coverage while minimizing number of bases. For instance, there may be a number of stations that use dipole antennas that are wider spaced with a large, but acceptable, marginal signal strength that are interconnected via a network of directional repeaters. This would allow the directional repeaters to operate a lower power and therefore be smaller than the broadcast bases.

Both modules make mention of being radio, satellite, microwave relay capable. They also mention a 50m mast, but no further details.

My understanding is that these are relay stations.

One thing that I've done in my games is equip the team with a dozen footlocker-sized units that contain a 15m antenna, solar cell panels, batteries and a radio set for retrans only. The idea is to set one up every 30-40 kms for broadcasting the team's transmissions. Secondary use is to help ID areas were their survivors that understand technology....when they scavenge the retrans equipment.