Return-Path: Received: from mtain-mc06.r1000.mx.aol.com (mtain-mc06.r1000.mx.aol.com [172.29.96.78]) by air-dd08.mail.aol.com (v129.4) with ESMTP id MAILINDD083-865e4d09064521d; Wed, 15 Dec 2010 13:17:41 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mc06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 60ED638000102; Wed, 15 Dec 2010 13:17:39 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PSvuM-0005Jn-Hj for rs_out_1@blacksheep.org; Wed, 15 Dec 2010 18:16:58 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PSvuL-0005Je-SF for rsgb_lf_group@blacksheep.org; Wed, 15 Dec 2010 18:16:57 +0000 Received: from cavuit01.kulnet.kuleuven.be ([134.58.240.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PSvuJ-0006f0-0U for rsgb_lf_group@blacksheep.org; Wed, 15 Dec 2010 18:16:57 +0000 Received: from smtps02.kuleuven.be (smtpshost02.kulnet.kuleuven.be [134.58.240.75]) by cavuit01.kulnet.kuleuven.be (Postfix) with ESMTP id 3D2FE7B804D for ; Wed, 15 Dec 2010 19:16:40 +0100 (CET) Received: from ICTS-S-HUB-N3.luna.kuleuven.be (icts-s-hub-n3.luna.kuleuven.be [10.112.9.13]) by smtps02.kuleuven.be (Postfix) with ESMTP id 20E7DF3862 for ; Wed, 15 Dec 2010 19:16:40 +0100 (CET) Received: from ICTS-S-EXC2-CA.luna.kuleuven.be ([10.112.11.13]) by ICTS-S-HUB-N3.luna.kuleuven.be ([10.112.9.13]) with mapi; Wed, 15 Dec 2010 19:16:40 +0100 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" Date: Wed, 15 Dec 2010 19:16:38 +0100 Thread-Topic: LF: Re: Earth Antennnas - General question Thread-Index: AcucehN2o9P7nB8CS/K54TGsIEBG+wACQ70i Message-ID: References: <1292360809.3356.74.camel@gerhard-desktop> <003701cb9be9$46bb5b00$0401a8c0@xphd97xgq27nyf> <4D08D9C8.50607@o2.ie>,<002f01cb9c79$9aa23a50$0401a8c0@xphd97xgq27nyf> In-Reply-To: <002f01cb9c79$9aa23a50$0401a8c0@xphd97xgq27nyf> Accept-Language: nl-NL, nl-BE Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: nl-NL, nl-BE MIME-Version: 1.0 X-KULeuven-Information: Katholieke Universiteit Leuven X-KULeuven-Scanned: Found to be clean X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: RE: LF: Re: Earth Antennnas - General question Content-Type: multipart/alternative; boundary="_000_BF4A524700075746A6467658DFC7102C886FDD753EICTSSEXC2CAlu_" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.1 required=5.0 tests=HTML_FONTCOLOR_BLUE, HTML_MESSAGE,TO_ADDRESS_EQ_REAL autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G x-aol-sid: 3039ac1d604e4d090643699c X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --_000_BF4A524700075746A6467658DFC7102C886FDD753EICTSSEXC2CAlu_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable This is an interesting experiment and my first thought would be that it is= behaving like a Beverage antenna. At 23.4kHz a 25m long wire less than 0.2% of the wavelength. It would be the same as claiming that a 30cm (1 ft) long wire could act as= a beverage antenna on 160m ;-) 73, Rik ON7YD - OR7T ________________________________________ Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.or= g] namens mal hamilton [g3kevmal@talktalk.net] Verzonden: woensdag 15 december 2010 18:00 Aan: rsgb_lf_group@blacksheep.org Onderwerp: Re: LF: Re: Earth Antennnas - General question Hi Tony Nice to see you join in on the discussion. This is an interesting experiment and my first thought would be that it is behaving like a Beverage antenna. Direction might indicate something for instance rotate it 90 degs and check the signal strength One experiment I thought might be interesting is to resonate a low long wi= re height say 20 ft and 200 ft long earthed by a spike at the far end and fee= d the near end with a signal. The signal source sent via coax, the centre pi= n to the wire and the earth shield to a ground pin. then put an atu between the coax shield and the near ground pin and resonate it if possible ie a tuned ground as well as a tuned/resonated wire. This antenna would really be a Grounded quad loop, the 200 ft wire plus 20 ft height x 2=3D=3D 240 ft total and the earth/ground would be the other= half ie total length 2 x 240 =3D=3D 480 ft. The theory is that the ground would pr= ovide a mirror image of the wire above it. So for vertical quad loops, delta loo= ps you only need build one half above ground and the ground provides the oth= er hal There was an article years ago in QST magazine by Belrose that explained= the theory for an 80m grounded delta loop. Natural resonance should be 2 Mcs Resonate the wire at a frequency of choice This is all interesting but I prefer to use a more convential antenna syst= em that I know will work 73 es gl de mal/g3kev ----- Original Message ----- From: "Tony" To: Sent: Wednesday, December 15, 2010 3:07 PM Subject: Re: LF: Re: Earth Antennnas - General question > Hi Mal & LF > > Your comments prompted me to carry out some simple tests today. > I layed out a 25m length of Thompson RG 214/U double screened coax on > the lawn and connected the centre conductor at the far end to a > stainless steel rod abt 300mm long pressed into moist soil. > In the shack I measured the signal strength of DHO-38 at -51 dB with the > coax screen connected to the station earth. > I then disconnected the station earth and still measured -51 db and then > I strapped screen and conductor together and still measured -51dB > Then I added an extra 10m of coax and elevated it all to an average of > 2m above the ground and carried out all the above again with absolutely > no difference in signal strength. > Finally I pulled the earth rod out of the ground and the signal dropped > to -94 dB and then I disconnected the coax totally from the earth rod > and the signal dropped to -102 dB. > Make of that what you will. > > I also out of interest connected my MFJ antenna analyser and found that > the SWR was fairly flat across the whole spectrum (between 2:1 and 8:1) > from 1.8 MHz to 150 MHz, although I don't think I will hear much on 2m > > 73, Tony, EI8JK. > > . > On 14/12/2010 23:47, mal hamilton wrote: > > Gerhard > > Yes the antennas described by Stefan and Roger and others are of the LOSSY > > variety and similar to Beverages. > > I have made this observation before. I cannot see how these elevated > > antennas can be considered Earth Mode since they propagate a signal in= to the > > ether to be received at a distance by another elevated antenna several > > metres above ground. > > de mal/g3kev > > > > > > ----- Original Message ----- > > From: "Gerhard Hickl" > > To: > > Sent: Tuesday, December 14, 2010 9:06 PM > > Subject: LF: Earth Antennnas - General question > > > > > >> Hi all ! > >> > >> I was following the whole discussion about the so called "earth-mode" > >> and the used antennas with interest. > >> > >> Mal told us that he sees those antennas as "lossy dipoles" while othe= rs > >> stated they are "true" earth-antennas. > >> > >> I don't have the theoretical background to tell you why but out of my > >> feeling, all those antennas described remind me on the well-known > >> Beverage-Antenna system. > >> > >> Two wires of any layout, diameter, height and length terminated by a > >> "resistor"...the soil. > >> > >> Could that be a way we could look at this kind of antenna? > >> And if so, what would it explain? > >> > >> 73 > >> OE3GHB > >> Gerhard > >> > >> > >> > >> > >> > >> > >> > > > > > > --_000_BF4A524700075746A6467658DFC7102C886FDD753EICTSSEXC2CAlu_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

This is an interesting experiment and my fi= rst thought would be that it is behaving like a Beverage antenna.

At  23.4kHz  a 25m long wire less than 0.2% of the wav= elength.

It would be the same as claiming th= at a 30cm (1 ft) long wire could act as a beverage antenna on 160m ;-= )

73, Rik  ON7YD - OR7T

 

________________________________________
Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.or= g] namens mal hamilton [g3kevmal@talktalk.net]
Verzonden: woensdag 15 december 2010 18:00
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: Re: Earth Antennnas - General question

Hi Tony
Nice to see you join in on the discussion.
This is an interesting experiment and my first thought would be that it is=
behaving like a Beverage antenna. Direction might indicate something for instance rotate it 90 degs and check the signal strength
One experiment I thought might be interesting is to resonate a low long wi= re
height say 20 ft and 200 ft long earthed by a spike at the far end and fee= d
the near end with a signal. The signal source sent via coax, the centre pi= n
to the wire and the earth shield to a ground pin.
then
put an atu between the coax shield and the near ground pin and resonate it=
if possible ie a tuned ground as well as a tuned/resonated wire.

This antenna would really be a Grounded quad loop, the 200 ft wire plus 20=
ft height x 2=3D=3D 240 ft total and the earth/ground would be the other= half ie
total length 2 x 240 =3D=3D 480 ft. The theory is that the ground would pr= ovide
a mirror image of the wire above it. So for vertical quad loops, delta loo= ps
you only  need build one half above ground and the ground provides th= e other
hal
There was an article years ago in QST magazine by Belrose that explained= the
theory for an 80m grounded delta loop.

Natural resonance should be 2 Mcs

Resonate the wire at a frequency of choice

This is all interesting but I prefer to use a more convential antenna syst= em
that I know will work

73 es gl de mal/g3kev


----- Original Message -----
From: "Tony" <ei8jk@o2.ie>
To: <rsgb_lf_group@blacksheep.org>
Sent: Wednesday, December 15, 2010 3:07 PM
Subject: Re: LF: Re: Earth Antennnas - General question


> Hi Mal & LF
>
> Your comments prompted me to carry out some simple tests today.
> I layed out a 25m length of Thompson RG 214/U double screened coax on=
> the lawn and connected the centre conductor at the far end to a
> stainless steel rod abt 300mm long pressed into moist soil.
> In the shack I measured the signal strength of DHO-38 at -51 dB with= the
> coax screen connected to the station earth.
> I then disconnected the station earth and still measured -51 db and= then
> I strapped screen and conductor together and still measured -51dB
> Then I added an extra 10m of coax and elevated it all to an average= of
> 2m above the ground and carried out all the above again with absolute= ly
> no difference in signal strength.
> Finally I pulled the earth rod out of the ground and the signal dropp= ed
> to -94 dB and then I disconnected the coax totally from the earth rod=
> and the signal dropped to -102 dB.
> Make of that what you will.
>
> I also out of interest connected my MFJ antenna analyser and found th= at
> the SWR was fairly flat across the whole spectrum (between 2:1 and 8:= 1)
> from 1.8 MHz to 150 MHz, although I don't think I will hear much on= 2m
>
> 73, Tony, EI8JK.
>
> .
> On 14/12/2010 23:47, mal hamilton wrote:
> > Gerhard
> > Yes the antennas described by Stefan and Roger and others are of= the
LOSSY
> > variety and similar to Beverages.
> > I have made this observation before. I cannot see how these elev= ated
> > antennas can be considered Earth Mode since they propagate a sig= nal into
the
> > ether to be received at a distance by another elevated antenna= several
> > metres above ground.
> > de mal/g3kev
> >
> >
> > ----- Original Message -----
> > From: "Gerhard Hickl"<gerhard.hickl@aon.at>
> > To:<rsgb_lf_group@blacksheep.org>
> > Sent: Tuesday, December 14, 2010 9:06 PM
> > Subject: LF: Earth Antennnas - General question
> >
> >
> >> Hi all !
> >>
> >> I was following the whole discussion about the so called &qu= ot;earth-mode"
> >> and the used antennas with interest.
> >>
> >> Mal told us that he sees those antennas as "lossy dipol= es" while others
> >> stated they are "true" earth-antennas.
> >>
> >> I don't have the theoretical background to tell you why but= out of my
> >> feeling, all those antennas described remind me on the well-= known
> >> Beverage-Antenna system.
> >>
> >> Two wires of any layout, diameter, height and length termina= ted by a
> >> "resistor"...the soil.
> >>
> >> Could that be a way we could look at this kind of antenna? > >> And if so, what would it explain?
> >>
> >> 73
> >> OE3GHB
> >> Gerhard
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >
> >
>
>

--_000_BF4A524700075746A6467658DFC7102C886FDD753EICTSSEXC2CAlu_--