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#1
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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? |
#2
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"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? ***Project Shun Notice*** Gareth Alun Evans G4SDW has been placed under a global shunning order by Project Shun for his continual, deranged trolling. Please help us make Usenet better by not responding to his malicious and lunatic postings. With thanks, Team Project Shun. ***end*** -- STC // M0TEY // twitter.com/ukradioamateur |
#3
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On 11/28/2015 4:11 PM, 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? One could. |
#4
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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. -- Extend ****s law - make 'em wear a cheat sheet 24/7 |
#5
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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. Thinking about how drooping the radials on a ground plane brings the feed impedance from 35 up to 50 ohms, I presume that bending a dipole has the same type of effect of reducing down from 72 ohms? |
#6
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"gareth" wrote:
"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. Thinking about how drooping the radials on a ground plane brings the feed impedance from 35 up to 50 ohms, I presume that bending a dipole has the same type of effect of reducing down from 72 ohms? ***Project Shun Notice*** Gareth Alun Evans G4SDW has been placed under a global shunning order by Project Shun for his continual, deranged trolling. Please help us make Usenet better by not responding to his malicious and lunatic postings. With thanks, Team Project Shun. ***end*** -- STC // M0TEY // twitter.com/ukradioamateur |
#7
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On 29/11/2015 12:25, gareth wrote:
Thinking about how drooping the radials on a ground plane brings the feed impedance from 35 up to 50 ohms, I presume that bending a dipole has the same type of effect of reducing down from 72 ohms? A good point and something I hadn't considered! -- Extend ****s law - make 'em wear a cheat sheet 24/7 |
#8
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In message , gareth
writes "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. Thinking about how drooping the radials on a ground plane brings the feed impedance from 35 up to 50 ohms, I presume that bending a dipole has the same type of effect of reducing down from 72 ohms? To get near 72 ohms, you would need to have the radials vertically downwards - so essentially you would have the makings of a centre-fed sleeve dipole. However, a side-effect would be that the coax would be fairly lively at RF, and if you didn't want to live with it, additional decoupling would be needed to kill it off. -- Ian |
#9
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On 29/11/2015 12:18, Fred Roberts wrote:
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. Gareth is missing the point of the multitude of radials, which are there essentially to get the ground in the radial arc looking like a sheet of metal (and thus lowering the angle of the main lobe). Ideally they should run out to 2.5 lambda, but I didn't have enough wire :-( The bent arm of the dipole can't do that, and is essentially a convenient place to attach the coax outer. -- Spike "Crime butchers innocence to secure a throne, and innocence struggles with all its might against the attempts of crime" - Maximilien Robespierre |
#10
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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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