Return-Path: X-Spam-DCC: paranoid 1102; Body=1 Fuz1=3 Fuz2=3 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_30_40,HTML_MESSAGE autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id t4T9L4hw027068 for ; Fri, 29 May 2015 11:21:04 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1YyGMl-0004QW-3f for rs_out_1@blacksheep.org; Fri, 29 May 2015 10:14:11 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1YyGMk-0004QN-Ep for rsgb_lf_group@blacksheep.org; Fri, 29 May 2015 10:14:10 +0100 Received: from smtp2-g21.free.fr ([212.27.42.2]) by relay1.thorcom.net with esmtps (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.85) (envelope-from ) id 1YyGMe-0004tb-9u for rsgb_lf_group@blacksheep.org; Fri, 29 May 2015 10:14:09 +0100 Received: from F6CNIToshiba (unknown [83.153.241.20]) by smtp2-g21.free.fr (Postfix) with SMTP id 00DAB4B028B; Fri, 29 May 2015 11:12:18 +0200 (CEST) Message-ID: From: =?iso-8859-1?B?R3V56SBBbmRy6Q==?= To: References: <394FEA4DA5AA4542828CB5F63AEE2C88@F6CNIToshiba> <474231660.434744.1432735092592.JavaMail.yahoo@mail.yahoo.com> <556640CA.1080101@posteo.de> <633B30A9-8836-44B6-850C-4DA304E51048@gmail.com> In-Reply-To: <633B30A9-8836-44B6-850C-4DA304E51048@gmail.com> Date: Fri, 29 May 2015 11:14:02 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 16.4.3528.331 X-MimeOLE: Produced By Microsoft MimeOLE V16.4.3528.331 X-Antivirus: avast! (VPS 150528-1, 28/05/2015), Outbound message X-Antivirus-Status: Clean X-Scan-Signature: eb65b97b00a71049be1fa526941c7b31 Subject: LF: MF mobile antenna and modeling it. Content-Type: multipart/alternative; boundary="----=_NextPart_000_000E_01D09A00.91766F80" 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 3339 Ce message est composi et au format MIME. ------=_NextPart_000_000E_01D09A00.91766F80 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi to all The best way modeling a short antenna is to use a good software as EZNEC (o= n the way, the new 6.0 version is on the W7EL site). But also you can have a look at one of all time best paper speaking about t= he short antennas on low bands : the Rick ON7YD here : http://www.strobbe.= eu/on7yd/136ant/ You can easily found that a 2 meters long 2 cm OD vertical= whip has 23 pF Best 73 - Andy F6CNI. P.S. Again sorry about my poor english... -----Message d'origine----- From: John Rabson Sent: Thursday, May 28, 2015 4:24 PM To: rsgb_lf_group@blacksheep.org Subject: Re: LF: MF mobile ? > I recall a few years one of the British Telecommunications journals (POEE= J/BTTJ/IBTE/TCNJ - I forget which name it was using at the time) had an ite= m about a low-loader mounted LF/VLF station which had a radiator supported = by a helium balloon. Or was it the Navy's definition of mobile: anything y= ou can move around with a battleship? John F5VLF > On 28 May 2015, at 00:10, DK7FC wrote: > > Hmm, i find someone should do a real mobile (mobile-mobile, with a veloci= ty > 0) experiment. A 1.5 m long CB antenna with a special preparated feed = point should work. And i think that the wire works better with a fixed C in= parallel, even if this reduces the efficiency. But it stabilises the SWR o= r better said, the voltage on the wire. Corona? Where is the problem with c= orona? :-) > Markus, could you calculate the ERP when 10 kV rms is applied to a 1.5m h= igh antenna on a car roof? I bet you have all the formulas in your mind :-)= > > Maybe the antenna has 10 pF. I remember i have a 470pF/16kV capacitor at = home. So if C =3D 470 pF and f =3D 475 kHz, L =3D 239 uH With 470 pF parall= el to the antenna, a moving wire (=3D changing C) does not make a significa= nt effect i think. > 10 kV at 239 uH at 10 kV is 14A. If P =3D 200 W, the losses must be 1 Ohm= ! > With a good RF litz wire, this is possible :-) > > What would be the ERP and possible distance? > > It would be interesting to try that in WSPR / QRSS-60 :-) I would also dr= ive to someone for making a CW QSO but most likely there is a LOT of QRM wh= en driving... > > More ideas? > > 73, Stefan john.rabson07@gmail.com Researching history of RABSON, BLACKSHAW, GAUNTLETT, VERLANDER and ROBSONNE= --- L'absence de virus dans ce courrier =E9lectronique a =E9t=E9 v=E9rifi=E9e p= ar le logiciel antivirus Avast. http://www.avast.com ------=_NextPart_000_000E_01D09A00.91766F80 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi to all
 
The best way modeling a short antenna is to use a good= software as EZNEC (on the way, the new 6.0 version is on the W7EL site).
 
But also you can have a look at one of all time best p= aper speaking about the short antennas on low bands : the Rick ON7YD here : = ; http://www.strobbe.eu/on7yd/13= 6ant/ You can easily found that a 2 meters long 2 cm OD vertical whip has 23 pF
 
Best 73 - Andy F6CNI.
 
P.S. Again sorry about my poor english...
 
-----Message d'origine-----
From: John Rabson
Sent: Thursday, May 28, 2015 4:24 PM
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: MF mobile ?
 
> I recall a few years one of the British Telecommunications journa= ls (POEEJ/BTTJ/IBTE/TCNJ - I forget which name it was using at the time) had a= n item about a low-loader mounted LF/VLF station which had a radiator support= ed by a helium balloon.  Or was it the Navy's definition of mobile: anything= you can move around with a battleship?
 
John F5VLF
 
> On 28 May 2015, at 00:10, DK7FC <selberdenken@posteo.de> wrote:
>
> Hmm, i find someone should do a real mobile (mobile-mobile, with = a velocity > 0) experiment. A 1.5 m long CB antenna with a special prepara= ted feed point should work. And i think that the wire works better with a fixed= C in parallel, even if this reduces the efficiency. But it stabilises the SWR or= better said, the voltage on the wire. Corona? Where is the problem with cor= ona? :-)
> Markus, could you calculate the ERP when 10 kV rms is applied to = a 1.5m high antenna on a car roof? I bet you have all the formulas in your mi= nd :-)
>
> Maybe the antenna has 10 pF. I remem= ber i have a 470pF/16kV capacitor at home. So if C =3D 470 pF and f =3D 475 kHz, = L =3D 239 uH With 470 pF parallel to the antenna, a moving wire (=3D changing C) does= not make a significant effect i think.
> 10 kV at 239 uH at 10 kV is 14A. If P =3D 200 W, the losses must = be 1 Ohm !
> With a good RF litz wire, this is possible :-)
>
> What would be the ERP and possible distance?
>
> It would be interesting to try that in WSPR / QRSS-60 :-) I would= also drive to someone for making a CW QSO but most likely there is a LOT of QRM = when driving...
>
> More ideas?
>
> 73, Stefan
 
john.rabson07@gmail.com
 
Researching history of RABSON, BLACKSHAW, GAUNTLETT, VERLANDER and ROBSONNE
 
 
 
 


3D"Avast

L'absence de virus dans ce courrier =E9lectronique a =E9t=E9 v=E9rifi= =E9e par le logiciel antivirus Avast.
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