Is the 1/2 silver rod the best antenna in the world ?

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ghost123uk
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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by ghost123uk »

Flat_Battery wrote:
07 Apr 2020, 16:28
I found this http://www.dx-antennas.com/Half%20wave%20vertical.htm, I guess it depends to on location and what you are after. what's your experience at 1/2 wave :D Thanks
Good info in there Image

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John, on the S. Cheshire / N. Shropshire border. 26TM953 / muppet handle "Grey ghost"
Don't just monitor, key up and talk, otherwise everyone thinks no one else is out there !!!

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InTheClouds
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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by InTheClouds »

According to those diagrams I guess it is pure luck as to where your DX copy's QTH is. If you are going for F2 layer long DX then the higher the better for the low angle lobe. For shorter Sporadic E it won't seem to make much difference and A or B would seem fine. For local contacts the higher the better.
Am I gettin aaat ? My CB gear = any old long antenna, any 11m radio, low SWR, good coax, get it up high, and most important of all a respect all radio colleagues attitude.

108EH002
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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by 108EH002 »

Its pure luck where YOUR location is aswell In the clouds with dx-ing imo.

Computer models are ok,but don't show the obstacles we all have around us in the real world.

And especially if ourselves or the other stations can't hear each other,because of high static/white noise at either end.
Plenty are talking worldwide on 27.555 usb,
Some are too far up their own @rse to admit it,
Many happen to know otherwise dx-ing test free,
Showing a complete lack of respect for the law.

27.555 Usb

Cornelius
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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by Cornelius »

An amateur here in Norway has written an article regarding how an antenna behaves in free space and above ground... Written in Norwegian though, so use Google translate... :)

wa10
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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by wa10 »

The amateur in Norway is modeling a best case scenario, no conductive mast & feed-line, its difficult to achieve that in the real world

in the real world you must use a feed-line & possibly a conductive mast too which must be included in the model to see how they perform how we use them,

best case been mast & coax lengths that have a high common mode impedance causing low current & very little radiation spoiling your low angle gain,

worst case been mast or coax length that has a low common mode impedance causing higher unwanted current & radiation spoiling your low angle pattern.
W8JI
"An antenna with a poor ground using few radials cannot have a support mast grounded to the radial common point (at least it shouldn't if designed properly) There is no exception to this!

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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by Cornelius »

wa10 wrote:
12 Apr 2020, 00:07
The amateur in Norway is modeling a best case scenario, no conductive mast & feed-line, its difficult to achieve that in the real world
This is true, but it gives you a better understanding, and a good starting point to what one want to achieve... ;)

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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by wa10 »

The article shows dipoles or other antennas don't radiate perfectly horizontal towards the horizon when you mount them over earth :thumbup: ,
its easy to make antennas look good on paper if you eliminate from the model real world things ( mast feed-line earth ) that skew your pattern ;)
W8JI
"An antenna with a poor ground using few radials cannot have a support mast grounded to the radial common point (at least it shouldn't if designed properly) There is no exception to this!

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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by The Collector »

Picking people's brains for a minute on this subject...

Would my aerial (25ft Imax - has 9ft tank-whip top section) be best fitted 18ft up or 25ft up on masts (1/2 vs it's own height, distances from ground level)? I appreciate the extra 7ft would mean more clearance above the roof, but would it make a difference radiation-wise?

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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by InTheClouds »

Put it up higher, that is unlikely to be a regret in this game. It will likely be 7ft away from sources of noise as well and your "I-Max" will be 7ft higher as well, a win win. The only other issue of concern is of it falling in wind and if anyone might complain.
Am I gettin aaat ? My CB gear = any old long antenna, any 11m radio, low SWR, good coax, get it up high, and most important of all a respect all radio colleagues attitude.

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The Collector
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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by The Collector »

InTheClouds wrote:
24 Apr 2020, 07:16
Put it up higher, that is unlikely to be a regret in this game. It will likely be 7ft away from sources of noise as well and your "I-Max" will be 7ft higher as well, a win win. The only other issue of concern is of it falling in wind and if anyone might complain.
I thought that might be the case, so I've been welding todsy and the sliding bracket for my mast is now ready for an extra 3m alloy pole ;) That means the base on my Imax will be about 12ft from the ground when lowered down - about where it was in the tree until today (took it down) - then about 30ft to the base when it's cranked up. It won't be up very often... oooeer missus.

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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by barefootindian »

What is the screw for near the bottom but just above the rectangular fixing plate on the half wave silver rod? Is it for grounding purposes or is it for drainage purposes?If wires were to be used as a ground plane, should they be fitted to the rectangular plate or onto the screws on the SO-239 feed plate? for better performance. I got one delivered today from Knights as I just wanted to try one out.I was going to use speaker wire for the ground planes and some bailing twine attached to them. Thanks for any help answering my questions.

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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by The Collector »

On the old rods, if you undid the screw (self-tapper), you could carefully slide the alloy pole up and access the little circuit board or coil inside. I'm not sure if there's a different screw on newer ones that you're referring to though sorry. I'm going back 40 years :)

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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by barefootindian »

I shone a torch down the inside of the bottom shaft and it doesn't look like there's a coil down there. It looked like the inside of a torch at the front. It looks to be flat metal in the center and a black ring of perhaps insulation all around that. I don't want to undo the end section in case I mess it up, like break a seal or something of that sort.
The screw appears to be very very short as it didn't intrude through the shaft wall.
There's no explanation leaflet with the antenna at all which to me is quite strange.
Anyway Thanks Collector for your answer.

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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by wa10 »

barefootindian

Silver rods usually have 3 or 4 screws through the bracket around the so239 to hold the coil housing & a small bolt that connects the radiator to the short aluminium rod that is embedded in the coil housing, that's the silver circle with black insulation round it you can see looking down the bottom section,

radials want to be connected to the bottom of the bracket near the coax connector on a 1/2wave,

to help the radials work as you want them to with a wide range of mast heights & coax lengths you can use something like a fork/spade handle in the top of your mast to isolate the antenna from the mast,

winding a 5 turn choke on a 4.25" former in your coax close to the antenna works a treat with most coax lengths to isolate the antenna from the coax outer braid, hopefully leaving the radials as the only easy path for return currents,

you can never eliminate the currents with any choke or any isolator, but you can encourage them to flow mostly where they won't screw with your radiation pattern.

Good luck
W8JI
"An antenna with a poor ground using few radials cannot have a support mast grounded to the radial common point (at least it shouldn't if designed properly) There is no exception to this!

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InTheClouds
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Re: Is the 1/2 silver rod the best antenna in the world ?

Post by InTheClouds »

As mentioned the screw just holds the coil in place. It is just a bit of wire wrapped round a bit of insulator, unless for curiosity alone
probably best to leave that bottom section untouched, tuning is just by length alone. Simplicity is part of the beauty of the old silver rod.
If I recall I think the screw going through actually makes the connection from the coil to the radiating element via a brass screw thread.
Go easy pushing your 259 in and out as the SO239's are pretty low quality riveted jobbys on the Venoms and they can end up inside the socket if you are connecting and reconnecting a lot.
Am I gettin aaat ? My CB gear = any old long antenna, any 11m radio, low SWR, good coax, get it up high, and most important of all a respect all radio colleagues attitude.

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