[TowerTalk] Fwd: Topband: Ground screen ????

[Hans Hammarquist]

 The problem using a metal roof as a ground plane is the possibility of rectification between the seams. The current will not be even across the seams and if (possibly more:" When ,,,") there is a bad connection at that point you might risk a rectification that will generate harmonics with possible RFI problems.

I would test it but would be very alert regarding harmonics.

Good luck with your installation and best 73 de,

Hans - N2JFS

 

 

-----Original Message-----
From: Brad Rehm <bradrehm at gmail.com>
To: Douglas Ruz (CO8DM) <co8dm at frcuba.co.cu>
Cc: towertalk <towertalk at contesting.com>; topband <topband at contesting.com>
Sent: Wed, Mar 2, 2016 9:12 am
Subject: Re: [TowerTalk] Topband: Ground screen ????

Douglas,You certainly can use the galvanized roof as a ground screen.  It might bea good idea to measure resistance between sheets to get an idea of how wellthey're all tied together electrically.  If they're not, you might see someodd shifts in VSWR when you send RF through it.  Another potential problemis that RF may be coupled into the building wiring when you transmit.  Thisis why you'll want to bring grounds up to the roof in as many places as youcan.But heck, try it!  Hams have made stranger things work as antennas.73,Brad  KV5VOn Tue, Mar 1, 2016 at 9:09 PM, Douglas Ruz (CO8DM) <co8dm at frcuba.co.cu>wrote:> Hi,>> Need some ideas from your side...>> I am trying to find a good solution for my 160/80m antenna.>> I am thinking about some kind of Inv L with an 80m trap as a radiator for> both bands.>> But, what about the counterpoise...Unfortunately in my small city lot I> can´t install radials and I can´t get parts for the FCP yet...what about a> Ground screen ???...I have a galvanized roof...it is about 50 ft long and> 16 ft wide...galvanized sheets are 3 by 8 ft long and all are bolted> together. The roof is about 15 ft high.>> Can I use this roof as a ground screen for the 160/80m antenna ???>> Thoughts ?,>> 73....Douglas, CO8DM> P.S:1- I finish my 50 ft tower installation.>        2- Thanks for all QSO´s on 160m before ARRL CW contest with me and> with our contest               station T48K.>> _________________> Topband Reflector Archives - http://www.contesting.com/_topband>______________________________________________________________________________________________TowerTalk mailing listTowerTalk at contesting.comhttp://lists.contesting.com/mailman/listinfo/towertalk