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Dave H
Guest
I thought that this might interest any CREG members or radio hams out there.
Now I've looked at the U.S. Navy's report and it says that they didn't test any antenna designed for less than 7MHz. But that the ones they did test worked comparibly with normal 1/4 wave designs.
If you can remember a few years ago, there was an aftermarket car aerial kit that had a helix at the bottom before reverting to a more conventional stick design. I understand that these new designs are similar except that the bottom of the stick part has been folded into the helix part.
The CREG group have been using ribbon cable over a wooden frame held vertically in a number of their experiments (it's especially good for locating null points above an underground transmitter, for instance). If one of these was extended (like pulling open a spring) and connected to a normal dipole aerial running through it's centre, then this may approximate to the test antenna.
I'm sure if R alph J obson or D ave G ibson are on this forum then they will tell me of the flaw in the idea - but I can't think that it wouldn't be worth trying it one day.
A research engineer at the University of Rhode Island has invented an
antenna 70 percent smaller than conventional designs, but which has
comparable sensitivity and increased bandwidth. The antenna, called a
distributed-load monopole (DLM), uses a helix and a load coil to shrink the
size of a normal quarter-wave monopole. In testing research engineer Rob
Vincent's antenna design, which cancels out the normal inductive loading,
the U.S. Navy found that the antenna achieved equivalent performance with
antennas 30 to 70 percent shorter than an ideal quarter-wave design. Read
more:
http://www.wirelessnetdesignline.com/showArticle.jhtml?articleID=163103803
Now I've looked at the U.S. Navy's report and it says that they didn't test any antenna designed for less than 7MHz. But that the ones they did test worked comparibly with normal 1/4 wave designs.
If you can remember a few years ago, there was an aftermarket car aerial kit that had a helix at the bottom before reverting to a more conventional stick design. I understand that these new designs are similar except that the bottom of the stick part has been folded into the helix part.
The CREG group have been using ribbon cable over a wooden frame held vertically in a number of their experiments (it's especially good for locating null points above an underground transmitter, for instance). If one of these was extended (like pulling open a spring) and connected to a normal dipole aerial running through it's centre, then this may approximate to the test antenna.
I'm sure if R alph J obson or D ave G ibson are on this forum then they will tell me of the flaw in the idea - but I can't think that it wouldn't be worth trying it one day.