[Lowfer] Another Antenna question
Bill Ashlock
ashlockw at hotmail.com
Thu May 29 14:35:05 EDT 2008
Andy,
You have raised some good points and Jay's suggestion that you check out the URL he gave you is a good one. One item you didn't mention is ground losses, and at 1750M it is probably the most significant portion of vertical antenna design to be considered..... And be careful not to fall into believing that your ground conductivity is the same as any author's ground conductivity - especially when comparing the typically good mid-western US ground conductivity with the poor eastern US ground conductivity (not to mention 'mountainous' ground conductivity where there is almost no conductivity at all!). You will find the ways to reduce this loss will vary according to the ground composition, whether it will be by using ground stakes, buried radials, surface radials, well casings, or my favorite for very poorly conducting soil, the elevated set of radials, AKA the counterpoise.
Good luck on this. You should find LF antenna design to be both fascinating and rewarding.
Bill
> From: jrusgrove at comcast.net
> To: lowfer at mailman.qth.net
> Subject: Re: [Lowfer] Another Antenna question
> Date: Thu, 29 May 2008 11:45:45 -0400
>
> Andy
>
> A good source of study material to provide answer to your questions can be
> found here:
>
> http://www.strobbe.eu/on7yd/136ant/
>
> Jay W1VD WD2XNS WE2XGR/2
>
>
> ----- Original Message -----
> From: "KU4XR"
> To:
> Sent: Thursday, May 29, 2008 11:14 AM
> Subject: [Lowfer] Another Antenna question
>
>
>> Hello Fellow LOWfers:
>>
>> I would appreciate any experienced input on some vertical antenna issues
>> for 1750 meters. " Using a vertical wire with top hat "; which would
>> radiate
>> better; a shorter vertical with longer top hat, or longer vertical with
>> shorter top hat ?? I would assume that the more wires you can include in
>> the top hat, the better the RF will reach the top and radiate. Is this
>> assumption correct or not ?? Has anyone tried hellically winding a
>> section,
>> say 20 feet ( bottom , middle , top section ) so the overall heigth would
>> be
>> a more one man manageable 30 feet ??. A realistic and do-able antenna for
>> me
>> would be a 20 foot vertical with a 30 foot top hat which can include many
>> wires
>> in different directions ( a capacitance issue only I'm sure ).
>> Would ground losses be more evident with a top hat version, or the
>> straight vertical ?
>> Any input will be valued and appreciated:
>>
>> 73, from Andy Bell - KU4XR - EM75xr
>>
>>
>>
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