I should have mentioned that the shield on the RG59 is shorted with the center
conductor at both ends. My results with the dipole element cut for 80 meters
is that the dipole is un-tunable with an antenna analyzer. In fact, the
antenna does not tune to anything from 1.8mhz to 14.5mhz. At the cut
frequency, the impedance is 50 ohms, but the SWR is greater than 10:1. I have
used RG58 with good results. I used RG59 because it's diameter is larger than
RG58 and should produce a larger bandwidth.
What am I doing wrong?
--jeff WB7AHT
-----Original Message-----
From: Grant Saviers <grants2@pacbell.net>
Sent: Friday, August 10, 2018 9:35 AM
To: felix1063@comcast.net; towertalk@contesting.com
Subject: Re: [TowerTalk] RG-59
Yes, assuming you mean using the shield as the conductor. The larger the
diameter, the greater the bandwidth, thus RG59 shield helps a bit.
The formulas for diameter vs bw are in most handbooks. The RG59 insulation
reduces the velocity factor and thus the antenna will be electrically longer by
a few percent than the usual dipole formulas calculate. NEC based modeling
software can model the effects of thin insulation like on RG59.
Otherwise, it is a dipole and a choke is a good idea.
Grant KZ1W
On 8/9/2018 16:14 PM, felix1063@comcast.net wrote:
> Has anybody ever used RG-59 as the radiating elements in a dipole? If
> so, what were the results? Was it easy to tune? Did the bandwidth of
> the dipole change appreciably from using a piece of stranded wire? Was a
> balun used?
>
>
>
> Thanks,
>
>
>
> --jeff
>
> Wb7aht
>
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