Return-Path: Received: from mtain-ma11.r1000.mx.aol.com (mtain-ma11.r1000.mx.aol.com [172.29.96.19]) by air-df05.mail.aol.com (v126.13) with ESMTP id MAILINDF053-5ef44b62d812d1; Fri, 29 Jan 2010 07:44:02 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-ma11.r1000.mx.aol.com (Internet Inbound) with ESMTP id B682D38000232; Fri, 29 Jan 2010 07:44:00 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NaqBW-00071s-8H for rs_out_1@blacksheep.org; Fri, 29 Jan 2010 12:42:50 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NaqBV-00071j-MI for rsgb_lf_group@blacksheep.org; Fri, 29 Jan 2010 12:42:49 +0000 Received: from thsmsgxrt13p.thalesgroup.com ([192.54.144.136]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NaqBS-0000CN-SF for rsgb_lf_group@blacksheep.org; Fri, 29 Jan 2010 12:42:49 +0000 Received: from thsmsgirt24p.corp.thales (unknown [10.33.231.8]) by thsmsgxrt13p.thalesgroup.com (Postfix) with ESMTP id BB7D1360C60 for ; Fri, 29 Jan 2010 13:42:39 +0100 (CET) Received: from thsmsgiav13p.corp.thales (10.33.231.33) by thsmsgirt24p.corp.thales (8.5.103) id 4B0E9CC1007BB22F for rsgb_lf_group@blacksheep.org; Fri, 29 Jan 2010 13:42:39 +0100 Received: from (unknown [10.33.231.1]) by thsmsgiav13p.corp.thales with smtp id 50b7_1acc_c90b531c_0cd3_11df_bff3_0013725f4d82; Fri, 29 Jan 2010 13:42:39 +0100 Received: from NODALNET.clb.tcfr.thales (unknown [10.33.8.19]) by thsmsgirt11p.corp.thales (Postfix) with ESMTP id 714B9598049 for ; Fri, 29 Jan 2010 13:42:39 +0100 (CET) Received: by nodalnet.clb.tcfr.thales with Internet Mail Service (5.5.2653.19) id ; Fri, 29 Jan 2010 13:42:39 +0100 Message-ID: From: Jean-Louis.RAULT@fr.thalesgroup.com To: rsgb_lf_group@blacksheep.org Date: Fri, 29 Jan 2010 13:42:50 +0100 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) X-Spam-Score: 0.6 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,NO_REAL_NAME=0.55 Subject: RE: LF: Question to the groundwave Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01CAA0E0.91333572" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_FONTCOLOR_BLUE, HTML_FONTCOLOR_UNSAFE,HTML_MESSAGE,NO_REAL_NAME 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: 3039ac1d60134b62d8101560 X-AOL-IP: 193.82.116.20 ------_=_NextPart_001_01CAA0E0.91333572 Content-Type: text/plain Most of the G4FGQ softwares (Original, high-quality, radio engineering/modelling programs.Not freeware -- just free gifts -- ) are on http://www.zerobeat.net/G4FGQ/index.html#S102 73 de Jean-Louis F6AGR _____ From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Rik Strobbe Sent: Friday, January 29, 2010 10:22 AM To: rsgb_lf_group@blacksheep.org Subject: Re: LF: Question to the groundwave Hello Stefan, ground waves (surfaces waves) are a tricky thing. The assumption you made (+6dB TX power = double distance) takes only the 2D spreading loss into account. This would be correct if the ground would be a perfect conductor and if the earth would be flat. In reality you have 2 additional losses: diffraction loss (due to the earth curve) and ground loss. The bad message is that these losses both have a more or less 1D behavior, and thus their attenuation is more or less linear to the distance. The late G4FGQ wrote a very good DOS application (named GRNDWAVE3) where you can put in a lot of parameters (distance, antenna efficiency, frequency, ground type, TX power) and it gives you the path attenuation, field strength at RX end and RX antenna voltage. It must be on the web on several places (google it), but in case you cannot find it I can send it to you. Just as an example the path loss this programme gives for 137kHz and an average ground: 250km = 55.1dB 500km = 65.3dB 750km = 74.7dB 1000km = 83.5dB 2000km = 115.4dB 3000km = 144.5dB 4000km = 172.2dB 5000km = 199.0dB As you can see doubling the distance "costs" far more that 6dB (by surface wave, sky wave is a different story). I haven't kept any records by I think that the surface wave limit for most amateur stations is 1000-1200km (on 137kHz), maybe a bit more in QRSS. Beyond that you are far better of with sky waves. 73, Rik ON7YD - OR7T At 02:51 29/01/2010, you wrote: Hi Alan and LF, I know there are some of you who can easily answer my question that follows :-) The maximum distance of the groundwave at a specific fieldstrength E is (about) linear increasing with the antenna current of the TX antenna, right? So, if i have an antenna current of 0,5A and get a maximum distance of 1000km, i would reach 2000km with 1A (same RX, same surrounding noise level, same average ground properties, same OP ;-) )?. I expect, that the groundwave does not immediately stop beyond this 2000km border but rather decreases with 1/r, just as before. So, if we assume one is increasing the antenna current in the above example to 7A, is then a distance of 14000km possible? Sure, thats a very theoretical question since there will not be the same ground conductivity on the whole distance but anyway. And it is said that the groundwave is (nearly) not affected by the daytime, by the season and so on. There must be interferences with the sky wave, so QSB, but this does not affect the groundwave at an other RX QTH, where no sky wave is present!? If there is so much sea water between a transatlantic distance, why is it so difficult to do it with the groundwave? On HF or MF it is clear but on LF? Tnx for enlightning answers... Stefan/DK7FC _____ Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von ALAN MELIA Gesendet: Fr 29.01.2010 01:51 An: rsgb_lf_group@blacksheep.org Betreff: Re: LF: Ok its a sea path .. but this is getting silly Ah this 500k stuff is too easy Graham :-)) oh for 73kHz again ! Alan G3NYK ------_=_NextPart_001_01CAA0E0.91333572 Content-Type: text/html Content-Transfer-Encoding: quoted-printable

Most of the G4FGQ softwares= (Original, high-quality,=20 radio engineering/modelling programs.Not freeware --= just=20 free gifts -- ) are on http://www.zerobeat.net/G4FGQ/index.html#S102

73 de Jean-Louis F6AGR

From: owner-rsgb_lf_group@blacksheep= .org=20 [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Rik=20 Strobbe
Sent: Friday, January 29, 2010 10:22 AM
To:= =20 rsgb_lf_group@blacksheep.org
Subject: Re: LF: Question to the= =20 groundwave

Hello Stefan,

ground waves (surfaces waves) are a tric= ky=20 thing.
The assumption you made (+6dB TX power =3D double distance) ta= kes only=20 the 2D spreading loss into account. This would be correct if the ground= would=20 be a perfect conductor and if the earth would be flat.
In reality you= have=20 2 additional losses: diffraction loss (due to the earth curve) and groun= d=20 loss.
The bad message is that these losses both have a more or less= 1D=20 behavior, and thus their attenuation is more or less linear to the=20 distance.
The late G4FGQ wrote a very good DOS application (named=20 GRNDWAVE3) where you can put in a lot of parameters (distance, antenna= =20 efficiency, frequency, ground type, TX power) and it gives you the path= =20 attenuation, field strength at RX end and RX antenna voltage.
It mus= t be=20 on the web on several places (google it), but in case you cannot find it= I can=20 send it to you.
Just as an example the path loss this programme = gives=20 for 137kHz and an average ground:
250km =3D 55.1dB
500km =3D 65.3d= B
750km=20 =3D 74.7dB
1000km =3D 83.5dB
2000km =3D 115.4dB
3000km =3D 144.= 5dB
4000km=20 =3D 172.2dB
5000km =3D 199.0dB
As you can see doubling the distanc= e "costs"=20 far more that 6dB (by surface wave, sky wave is a different story).
I= =20 haven't kept any records by I think that the surface wave limit for most= =20 amateur stations is 1000-1200km (on 137kHz), maybe a bit more in QRSS.= Beyond=20 that you are far better of with sky waves.

73, Rik ON7YD -= =20 OR7T

At 02:51 29/01/2010, you wrote:

Hi Alan= and LF,=20

I know there are some of you who= can=20 easily answer my question that follows :-)

The maximum distance of the groundwave at a specific fields= trength E=20 is (about) linear increasing with the antenna current of the TX antenn= a,=20 right?
So, if i have an antenna current of 0,5A and get a maximum= =20 distance of 1000km, i would reach 2000km with 1A (same RX, same surrou= nding=20 noise level, same average ground properties, same OP ;-)=20 )?.

I expect, that the groundwave= does not=20 immediately stop beyond this 2000km border but rather decreases with= 1/r,=20 just as before.

So, if we assume one is increasing= the=20 antenna current in the above example to 7A, is then a distance of 1400= 0km=20 possible? Sure, thats a very theoretical question since there will not= be=20 the same ground conductivity on the whole distance but=20 anyway.

And it is said that the groundwave is (nearly) no= t=20 affected by the daytime, by the season and so on. There must be=20 interferences with the sky wave, so QSB, but this does not affect the= =20 groundwave at an other RX QTH, where no sky wave is=20 present!?

If there is so much sea water between a transat= lantic=20 distance, why is it so difficult to do it with the groundwave? On HF= or MF=20 it is clear but on LF?

Tnx for enlightning=20 answers...

Stefan/DK7FC

Von: owner-rsgb_lf_group@blackshee= p.org im=20 Auftrag von ALAN MELIA
Gesendet: Fr 29.01.2010 01:51
A= n:=20 rsgb_lf_group@blacksheep.org
Betreff: Re: LF: Ok its a sea= path ..=20 but this is getting silly

Ah this 500k st= uff is=20 too easy Graham :-)) oh for 73kHz again !

Alan=20 G3NYK

------_=_NextPart_001_01CAA0E0.91333572--