Radials or counterpoise for a mobile antenna
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| Nov 23rd 2015, 16:09 | |
K2FITotal Topics: 0 Total Posts: 0 |
Greetings, I'm starting to get back into ham radio after about 20 years away. (I've been relicensed for a year and a half, but I'm only now starting to really operate). I'm using an FT-817nd as my rig and for quick portable operations I've hacked a folding music stand into a mount for an MFJ-1899T (not as a main antenna, but this is something I can have set up in under a minute). Over on FB, someone suggested adding tuned radials to it but I haven't really been able to find out much info about what size that means for each band. Would I do better with a counterpoise (a metal tape measure works well enough for that)? Any thoughts would be greatly appreciated. If the link works, this is what the antenna setup looks like (not extended, obviously) https://www.flickr.com/photos/filkerdave/22926921620/in/album-72157660827162339/ |
| Nov 24th 2015, 05:05 | |
WA0CBWTotal Topics: 0 Total Posts: 0 |
As suggested this antenna needs a ground plane to provide the other "half" of the antenna. This can be provided by adding (one or more) 1/4 wavelength radials for each frequency in use. Of course the more radials the better however for a portable antenna use as many as you can deploy. These radials can be wire or as you mentioned a metal tape measure(s). The radials can lay on the ground and should radiate outward from the base of the antenna with the base of the antenna only a few inches above the ground. The radials can also be elevated if the antenna is mounted above the ground as shown in your pictures. The elevated radials can be somewhat of a hazard (since a 1/4 wavelength at 80 meters is about 60 feet). Since this is a portable temporary antenna as many radials of any length are better than none. BB |
| Nov 24th 2015, 05:06 | |
WA0CBWTotal Topics: 0 Total Posts: 0 |
As suggested this antenna needs a ground plane to provide the other "half" of the antenna. This can be provided by adding (one or more) 1/4 wavelength radials for each frequency in use. Of course the more radials the better however for a portable antenna use as many as you can deploy. These radials can be wire or as you mentioned a metal tape measure(s). The radials can lay on the ground and should radiate outward from the base of the antenna with the base of the antenna only a few inches above the ground. The radials can also be elevated if the antenna is mounted above the ground as shown in your pictures. The elevated radials can be somewhat of a hazard (since a 1/4 wavelength at 80 meters is about 60 feet). Since this is a portable temporary antenna as many radials of any length are better than none. BB |
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