[TowerTalk] More Radials = Higher SWR???

Sun Feb 5 19:03:12 EST 2023

A full size vertical has a feed point impedance of 35 ohms give or take 
a couple.  A compromise vertical like yours would be even less ... 
probably 25 ohms or less.  When you don't use the radials your ground 
return resistance is high and it is in series with the antenna.  That 
might give you better SWR but the power lost in the ground resistance is 
wasted.

Your 2.2 SWR with 8 radials means that your antenna has no better than a 
feedpoint impedance of 23 ohms.  A 1.2 SWR is 47 ohms, so without any 
radials you have at least 25 ohms ground return resistance and you're 
losing at least half your power.

73,
Dave  AB7E

On 2/5/2023 4:34 PM, Test wrote:
> I recently erected  my first Vertical (Hy-Gain AV-18HT) antenna and the more
> I try improving it, the more confused I become.
> I added the Hy-Gain MK-160A kit that converts the Vertical to an "L" antenna
> on 160M. For the first time in 50 years of Ham Radio, I was able to work EU
> stations on 160M. WOW!!!!
> I decided to start "Improving" and added my first 4 radials. There's a
> rumor: "You gain and extra 6db of signal if you install antennas in the
> middle of winter in a blizzard." NOT TRUE!!!! The SWR went up a little
> higher, but still workable so I added 4 more.  Now the SWR is over 2:1 on
> all of 160M and is not usable for transmitting.  I disconnected the last 4
> radials from the ground plate but left them in place and now the SWR is back
> to 1.6.
> Grounding Issues? Maybe?
> The ground here is very poor with MANY rocks and solid basalt 18 inch down.
> 8ft ground rods are not practical.  Instead I have installed three 20ft
> galvanized 1 1/2 inch pipe buried as deep as possible in 3 directions from
> the base of the Vertical.  Also I have 500 ft #2 solid tinned ground wire
> bonding all antennas, towers, Vertical, Power entrance point and all devices
> in shack.  I'm located on an 800 ft cliff above Lake Coeur d' Alene in North
> Idaho and we get lots of lightning strikes but that's another story...
> All radials are evenly spaced and 65ft long.
> I'm not sure if I can included attachments of the comparison SWR Graphs so
> I'll also describe the comparisons:
> The colors refer to the attachment if present. The shift in resonates is
> explainable: The antenna wire was slightly lengthened.
> Below are the minimum SWR on 160M taken at the base of the Vertical..  All
> other bands were just slightly affected .
> No Radials= 1.2 SWR (Fuchsia)
> 4 Radials = 1.6 SWR (Red)
> 8 radials =  2.2 SWR Green)
> Any comments would be greatly appreciated!
> 73 es gud DX
> Dennis - K7OGW
>
>      
>
> -----Original Message-----
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> towertalk-request at contesting.com
> Sent: Sunday, February 5, 2023 9:00 AM
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> Subject: TowerTalk Digest, Vol 242, Issue 4
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> Today's Topics:
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>     1. Re: Tower mounted capture device (bill steffey ny9h)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 4 Feb 2023 20:40:55 -0500
> From: bill steffey ny9h <ny9h at comcast.net>
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Tower mounted capture device
> Message-ID: <6a703ed4-f398-e76b-9f14-2f91731e2b11 at comcast.net>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> the Tempest installed here will eventually trip the "lower the tower"
> circuit for both lightning and windspeed.
>
> Mine is mounted at the second topmost section... ?? 40-50 feet up . ? ?
> An old anemometer is mounted at the top and works with a Heliotrack
> programmable wind alarm switch. ?? The Tempest lightning sensor is very
> widely adjustable.
>
> Tempest will talk to any smart device.... which will throw your switches.
>
> bill
>
> On 1/31/2023 3:28 PM, Jim Miller wrote:
>> Google weather flow tempest.
>>
>> Wireless. Solar powered. No moving parts.
>>
>> Jim ab3cv
>>
>> On Tue, Jan 31, 2023 at 3:04 PM Richard Karlquist
>> <richard at karlquist.com>
>> wrote:
>>
>>> The only sensor you need up on the tower is an anemometer. since wind
>>> speed varies with HAAT.  Get a wired (not wireless) one to avoid
>>> having batteries at the unit.  Leave the WX station on the ground for the
> other
>>> readings, including ground wind speed.   You would want that in addition
>>> to wind speed at the top of the tower.
>>>
>>> Hazers are very fussy things that you should avoid if at all possible.
>>>
>>> --
>>>
>>> Rick Karlquist
>>> N6RK
>>>
>>> On 2023-01-31 08:21, Rick Harrington N0VT wrote:
>>>
>>>> I would like to have the sensing unit of my home weather station
>>>> near
>>> the top of my tower (80').  But instead of a fixed installation, I'd
>>> like to be able to raise/lower it via rope & pulley for battery
>>> changes, cleaning etc.  There would have to be a way at the top of
>>> the tower to dock it into the same north/south orientation each time.
>>> (I'm thinking of some sort of small hazer-like contraption.)
>>>> Has anyone ever done this, or seen info on doing it?
>>>>
>>>> 73,
>>>>
>>>> Rick N0VT
>>> _______________________________________________
>>>
>>>
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