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Build Your Own Antenna - Discuss topics for building your own antenna.

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Old 11-29-2017, 9:00 PM
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Default Diy monopole

I'm planning a Diy multiband monopole for my bcd996p2
It is three 1/8th inch copper rods cut to length connected to a copper block
What I don't know is how to connect the coax
I was thinking about using a twist on coax connector and a piece of scrap copper
But wasn't sure
Do I need a balem if I'm only receiving
Also curious what adapters have the lowest loss, bnc, f, n, tnc
I currently have one cable with bnc and tnc connectors
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Old 12-09-2017, 6:22 PM
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Adapter loss is so tiny you can't even measure it
All that you need to do is solder a rod into the center pin then solder
the other two to the same place
This will be fine for 50 ohm or 75 ohm feedline
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Old 12-09-2017, 7:09 PM
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A monopole is usually 1/4 wavelength and would need a ground plane. The braid of the coax would connect to the ground plane, which can be tuned radials or a sheet of metal or chicken wire at least 1/2 wavelength across on the lowest band. What bands are you making it for and how long are the rods?
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Quote:
Originally Posted by sonm10 View Post
I'm planning a Diy multiband monopole for my bcd996p2
It is three 1/8th inch copper rods cut to length connected to a copper block
What I don't know is how to connect the coax
I was thinking about using a twist on coax connector and a piece of scrap copper
But wasn't sure
Do I need a balem if I'm only receiving
Also curious what adapters have the lowest loss, bnc, f, n, tnc
I currently have one cable with bnc and tnc connectors
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Old 12-09-2017, 9:27 PM
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I wonder if he is thinking of this thing........ which is no more a J-Pole than a long wire!
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Old 12-10-2017, 3:23 AM
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I think he is trying to make something like this:

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Old 12-10-2017, 11:56 AM
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Quote:
Originally Posted by majoco View Post
I wonder if he is thinking of this thing........ which is no more a J-Pole than a long wire!
Yep, three 1/8th in copper rods cut for 855, 445, and 128
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Old 12-10-2017, 12:40 PM
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The picture in post 4 is not just a couple of 1/4 wave elements tied together, the short UHF element is the only driven one and it excites the larger VHF one via close proximity "sympathetic" resonance and the shortest element is for matching. In the end its a terrible antenna and not a J pole.

If you have three rods each a 1/4 wave long for each band you will need a ground plane, otherwise its just coat hangers hanging in the air.
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Yep, three 1/8th in copper rods cut for 855, 445, and 128
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