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"Fred Roberts" wrote in message
... On 28/11/2015 22:11, gareth wrote: Spike recently commented upon his success with DX by implementing at the base of his vertical antenna a fan of 300 ground wires pointing in the direction that he wished to work. I've not seen my suggestion before, but why could one not just have a 1/4 wave vertical, with the other 1/4 wave making up the dipole being rotatable for the desired direction of working? This was covered in, IIRC, Pat Hawkers Technical Topics many years ago. The Americans had done some research on this very topic during the Vietnam war, if one bends a vertical dipole so that the two elements are at right angles to each other it is possible it would seem to get some directivity in the direction of the horizontal element. As I'm sure we both know, if a horizontal half wave dipole is turned so the element runs east to west, the maximum radiation will be north and south, with nulls to the east and west. If the dipole is now turned vertically, the nulls would be upwards and downwards and the horizontal radiation would be omni-directional. I've not tried this, but my gut feeling is that if the elements were at right angles you would get a combination of the two radiation patterns, hence some degree of directivity in the form of a null in the direction the horizontal element was pointing. -- ;-) .. 73 de Frank Turner-Smith G3VKI - mine's a pint. .. http://turner-smith.uk |
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