Return-Path: Received: from rly-de06.mx.aol.com (rly-de06.mail.aol.com [172.19.170.142]) by air-de06.mail.aol.com (v125.7) with ESMTP id MAILINDE063-4df4b09e85f1cb; Sun, 22 Nov 2009 20:42:08 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-de06.mx.aol.com (v125.7) with ESMTP id MAILRELAYINDE062-4df4b09e85f1cb; Sun, 22 Nov 2009 20:41:53 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NCNv2-00079G-2U for rs_out_1@blacksheep.org; Mon, 23 Nov 2009 01:40:44 +0000 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NCNv1-000797-6g for rsgb_lf_group@blacksheep.org; Mon, 23 Nov 2009 01:40:43 +0000 Received: from blu0-omc1-s29.blu0.hotmail.com ([65.55.116.40]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NCNuz-0007G4-A8 for rsgb_lf_group@blacksheep.org; Mon, 23 Nov 2009 01:40:43 +0000 Received: from BLU146-W27 ([65.55.116.7]) by blu0-omc1-s29.blu0.hotmail.com with Microsoft SMTPSVC(6.0.3790.3959); Sun, 22 Nov 2009 17:40:33 -0800 Message-ID: X-Originating-IP: [138.32.254.21] From: Laurence BY3A-KL1X China To: Date: Sun, 22 Nov 2009 16:40:33 -0900 Importance: Normal In-Reply-To: <006101ca6bd9$9ab3cb70$0900a8c0@lark> References: <4B09D502.8030200@toya.net.pl>,<006101ca6bd9$9ab3cb70$0900a8c0@lark> MIME-Version: 1.0 X-OriginalArrivalTime: 23 Nov 2009 01:40:33.0231 (UTC) FILETIME=[F267BDF0:01CA6BDD] X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Content-Type: multipart/alternative; boundary="_7fbe74eb-3bca-40c4-8e34-0f40c66c5f3c_" Subject: RE: LF: Re: N-turn TX Loop X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=FORGED_HOTMAIL_RCVD, HTML_MESSAGE 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-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --_7fbe74eb-3bca-40c4-8e34-0f40c66c5f3c_ Content-Type: text/plain; charset="iso-8859-2" Content-Transfer-Encoding: quoted-printable Yep Ive just been discussed this with John TAG trying to recall what we ha= ve did- as ever my files are back in Alaska and Im here..=20 =20 I did "try" 2T (the loop was 4 large conductors in parallel separated betw= een metres on the vertical and top horizontal sections and about 5 Cms on= the lower horizontals) - the results did not give an improvement in far= field or local mobile field measurements, but, I did not fully investigat= e the other losses - my total loop current did decrease, and other losses= would indicate that this negated any "gain" perceived or otherwise... =20 Ive been racking my brains and as far as I can remember a single turn I re= alized around 49A loop current and 2T around 33A fully matched using the= "M0BMU scopematch" for around 1Kw into the loop. =20 Im sure there is more... =20 Laurence in BY3A =20 > From: alan.melia@btinternet.com > To: rsgb_lf_group@blacksheep.org > Date: Mon, 23 Nov 2009 01:09:24 +0000 > Subject: LF: Re: N-turn TX Loop >=20 > Hi Piotr I think Laurence KL1X had 2 turns in Oklahoma.(about 100m > periphery) > I think there are other loss problems as you increase the turns. Jim M0B= MU > is the expert on that. >=20 > Alan G3NYK >=20 > ----- Original Message ----- > From: "Piotr M=B3ynarski" > To: > Sent: Monday, November 23, 2009 12:19 AM > Subject: LF: N-turn TX Loop >=20 >=20 > > Dear LF group, > > I would like to put for your consideration the issue of > > multi-turn transmitting loops. Have you ever done such an experiment= on > > LF ? > > This sunday evening i decided to do some simple math and it turns out > > that such a N-turn TX loop should work ( at least on the paper) > > The radiation resistance is proportional to the square of so called > > "effective > > height" and this last term can be easily derived for a loop i.e. it is > > equal to > > 2*pi*A*N/lambda where A denotes area closed by a loop a N is the numbe= r > > of turns > > so the radiation resistance for a single turn loop reads as > > 320*pi^4*A^2/lambda^4 > > For the N-turns the radiation resistance obtained for a single turn is > > multiplied > > by N^2. Ok, the R (ac) is increased as we increase N but this is linea= r > > with respect to N > > and therefore we should have gain in the radiated power. > > (there is an implicit assumption made: the loop is "small" i.e. the > > current is constant) > > > > i did some calculations: assumed TX power ( and later, perfect match= to > > the loop) 200 Watt > > environmental loss: 1.5 Ohm, diameter of the wire d =3D 3 mm, rectangu= lar > > shape of the loop > > i.e 10 meters by 20 meters ( less optimal than square or circle ) > > so A =3D 200 sq.m For N =3D1 (classical tx loop) we get R(AC) =3D 0.62= Ohm > > ( Rac formula taken from ARRL Antenna Handbook, f =3D 137.7kHz) > > radiation resistance RRAD =3D 55.5 microOhm, total R loss =3D 2.12 Ohm= , > > efficiency is 0.0026% and radiated pwr 5.2 miliWatts, I =3D 9.7 Amp. > > Next, I took N =3D3 so the wire length is changed from 60 meters to 18= 0, > > everything else was kept the same and now one gets: R(ac)=3D 1.85 Ohm= so > > R loss =3D 3.35 Ohm > > RRAD =3D 499.5 microOhm, efficiency increased to 0.015% and radiated= pwr > > abt 30 miliWatt, I=3D7.7 Amp > > I am sorry bothering you but i simply would like to learn > > where is the 'catch' here - if there is one ... > > I guess the assumed loop i.e. 10 by 20 mters is 'reasonable' as TX ant= enna > > i took these values after reading the article about > > WD2XES first TX loop: 40 feet by 65 feet - well , almost the same > > dimensions.. :) > > From practical reasons the N values will likely be small , say, 2 or= 3 > > but as the above numbers show maybe it is worth doing it. > > > > 73 de Piotr, sq7mpj > > qth: Lodz /jo91rs/ > > >=20 >=20 =20 _________________________________________________________________ Windows 7: It works the way you want. Learn more. http://www.microsoft.com/Windows/windows-7/default.aspx?ocid=3DPID24727::T= :WLMTAGL:ON:WL:en-US:WWL_WIN_evergreen:112009v2=3D --_7fbe74eb-3bca-40c4-8e34-0f40c66c5f3c_ Content-Type: text/html; charset="iso-8859-2" Content-Transfer-Encoding: quoted-printable Yep Ive just been discussed this with John TAG trying to recall what= we have did- as ever my files are back in Alaska and Im here.. 
 
I did "try" 2T (the loop was 4 large conductors in parallel separated betw= een metres on the vertical and top horizontal sections and about 5 Cm= s on the lower horizontals) - the results did not give an improvement in= far field or local mobile field measurements, but, I did not fully= investigate the other losses - my total loop current did decrease, a= nd other losses would indicate that this negated any "gain" perceived= or otherwise...
 
Ive been racking my brains and as far as I can remember a single turn= I realized around 49A loop current and 2T around 33A fully matched using= the "M0BMU scopematch" for around 1Kw into the loop.
 
Im sure there is more...
 
Laurence in BY3A
 
> From: alan.melia@btinternet.com> To: rsgb_lf_group@blacksheep.org
> Date: Mon, 23 Nov 2009 01:0= 9:24 +0000
> Subject: LF: Re: N-turn TX Loop
>
> Hi Pio= tr I think Laurence KL1X had 2 turns in Oklahoma.(about 100m
> perip= hery)
> I think there are other loss problems as you increase the tu= rns. Jim M0BMU
> is the expert on that.
>
> Alan G3NYK<= BR>>
> ----- Original Message -----
> From: "Piotr M=B3yna= rski" <sq7mpj@toya.net.pl>
> To: <rsgb_lf_group@blacksheep.= org>
> Sent: Monday, November 23, 2009 12:19 AM
> Subject:= LF: N-turn TX Loop
>
>
> > Dear LF group,
>= > I would like to put for your consideration the issue of
> >= multi-turn transmitting loops. Have you ever done such an experiment on> > LF ?
> > This sunday evening i decided to do some sim= ple math and it turns out
> > that such a N-turn TX loop should= work ( at least on the paper)
> > The radiation resistance is pr= oportional to the square of so called
> > "effective
> >= height" and this last term can be easily derived for a loop i.e. it is> > equal to
> > 2*pi*A*N/lambda where A denotes area clos= ed by a loop a N is the number
> > of turns
> > so the= radiation resistance for a single turn loop reads as
> > 320*pi^= 4*A^2/lambda^4
> > For the N-turns the radiation resistance obtai= ned for a single turn is
> > multiplied
> > by N^2. Ok,= the R (ac) is increased as we increase N but this is linear
> >= with respect to N
> > and therefore we should have gain in the= radiated power.
> > (there is an implicit assumption made: the= loop is "small" i.e. the
> > current is constant)
> >> > i did some calculations: assumed TX power ( and later, perfect= match to
> > the loop) 200 Watt
> > environmental loss:= 1.5 Ohm, diameter of the wire d =3D 3 mm, rectangular
> > shape= of the loop
> > i.e 10 meters by 20 meters ( less optimal than= square or circle )
> > so A =3D 200 sq.m For N =3D1 (classical= tx loop) we get R(AC) =3D 0.62 Ohm
> > ( Rac formula taken from= ARRL Antenna Handbook, f =3D 137.7kHz)
> > radiation resistance= RRAD =3D 55.5 microOhm, total R loss =3D 2.12 Ohm,
> > efficienc= y is 0.0026% and radiated pwr 5.2 miliWatts, I =3D 9.7 Amp.
> >= Next, I took N =3D3 so the wire length is changed from 60 meters to 180,<= BR>> > everything else was kept the same and now one gets: R(ac)=3D= 1.85 Ohm so
> > R loss =3D 3.35 Ohm
> > RRAD =3D 499.5= microOhm, efficiency increased to 0.015% and radiated pwr
> > ab= t 30 miliWatt, I=3D7.7 Amp
> > I am sorry bothering you but i sim= ply would like to learn
> > where is the 'catch' here - if there= is one ...
> > I guess the assumed loop i.e. 10 by 20 mters is= 'reasonable' as TX antenna
> > i took these values after reading= the article about
> > WD2XES first TX loop: 40 feet by 65 feet= - well , almost the same
> > dimensions.. :)
> > From= practical reasons the N values will likely be small , say, 2 or 3
>= > but as the above numbers show maybe it is worth doing it.
> &g= t;
> > 73 de Piotr, sq7mpj
> > qth: Lodz /jo91rs/
>= ; >
>
>

Windows 7:= It works the way you want. Learn more. =3D --_7fbe74eb-3bca-40c4-8e34-0f40c66c5f3c_--