Not a biggy, but useful to know stuff.
A doublet and a dipole are basically the same thing. A distinction is made when calling it a dipole because a dipole is considered a 1/2 wave length long. So saying an antenna is a 40 meter dipole means you're talking about a 1/2 wave antenna. Calling it 40 meter doublet just means that there are equal length 'legs', one on each side. Each leg can be of almost any 'typical' length, 1/4 w, 1/2 w, 5/8 w, etc, so two of them mean the length is double each leg's length. I think I'm confusing my self, hope that makes sense.
What's the deal with ladder line? Very basically, it isn't affected by SWR like coaxial cable can be. Higher SWR with coax means that the coax cable is being operated above it's voltage/current ratings, so is typically destroyed/ruined. Ladder line just doesn't care until the SWR get's astronomically high (50:1 maybe?). Quite frankly, I couldn't care less what the SWR between ladder line and the antenna is as long as the tuner can handle it. Can you tell I like ladder line and tuners?
Ladder line has to be handled differently than coax. Can't lay it on the ground, make sharp bends with it, coil it up, etc. It ought'a be kept something like 3 or 4 times it's width away from stuff if possible. Twisting it into a 'spiral' helps keep it from flopping around in wind a lot, and when it rains/snows, the moisture on it changes it's 'tune' some. Really long runs of it don't have lots of losses, -much- less than any coaxial cable. But it doesn't play well with mobiles. Ladder line can also handle dang near any power level you can think of, and easily. Most ladder lines use 18 gauge 'Copperweld' wire for conductors. That means that you'd better know how to make good wire splices. It can scratch the 'fire' out of you, so pliers help. There are versions that use larger wire but I've found no particular need for it. It doesn't hurt, but it's just not necessary most cases. AND ... it's cheap!
- 'Doc
A doublet and a dipole are basically the same thing. A distinction is made when calling it a dipole because a dipole is considered a 1/2 wave length long. So saying an antenna is a 40 meter dipole means you're talking about a 1/2 wave antenna. Calling it 40 meter doublet just means that there are equal length 'legs', one on each side. Each leg can be of almost any 'typical' length, 1/4 w, 1/2 w, 5/8 w, etc, so two of them mean the length is double each leg's length. I think I'm confusing my self, hope that makes sense.
What's the deal with ladder line? Very basically, it isn't affected by SWR like coaxial cable can be. Higher SWR with coax means that the coax cable is being operated above it's voltage/current ratings, so is typically destroyed/ruined. Ladder line just doesn't care until the SWR get's astronomically high (50:1 maybe?). Quite frankly, I couldn't care less what the SWR between ladder line and the antenna is as long as the tuner can handle it. Can you tell I like ladder line and tuners?
Ladder line has to be handled differently than coax. Can't lay it on the ground, make sharp bends with it, coil it up, etc. It ought'a be kept something like 3 or 4 times it's width away from stuff if possible. Twisting it into a 'spiral' helps keep it from flopping around in wind a lot, and when it rains/snows, the moisture on it changes it's 'tune' some. Really long runs of it don't have lots of losses, -much- less than any coaxial cable. But it doesn't play well with mobiles. Ladder line can also handle dang near any power level you can think of, and easily. Most ladder lines use 18 gauge 'Copperweld' wire for conductors. That means that you'd better know how to make good wire splices. It can scratch the 'fire' out of you, so pliers help. There are versions that use larger wire but I've found no particular need for it. It doesn't hurt, but it's just not necessary most cases. AND ... it's cheap!
- 'Doc
