Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-ma06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 3FA0B38000097; Tue, 3 Jan 2012 08:55:28 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Ri4ob-0008Es-BB for rs_out_1@blacksheep.org; Tue, 03 Jan 2012 13:54:09 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Ri4oa-0008Ej-FU for rsgb_lf_group@blacksheep.org; Tue, 03 Jan 2012 13:54:08 +0000 Received: from smtpout4.wanadoo.co.uk ([80.12.242.68] helo=smtpout.wanadoo.co.uk) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Ri4oY-0000o0-IU for rsgb_lf_group@blacksheep.org; Tue, 03 Jan 2012 13:54:08 +0000 Received: from AGB ([2.26.9.122]) by mwinf5d53 with ME id H1tz1i00h2dymtu031u0tJ; Tue, 03 Jan 2012 14:54:00 +0100 Message-ID: <08E9AE01E10041AE96C43988F382210E@AGB> From: "Graham" To: References: <008301ccc97c$51d9fcf0$0401a8c0@xphd97xgq27nyf>, ,<003501ccca06$6bdef490$0401a8c0@xphd97xgq27nyf> In-Reply-To: Date: Tue, 3 Jan 2012 13:53:59 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8117.416 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416 X-Antivirus: avast! (VPS 120103-0, 03/01/2012), Outbound message X-Antivirus-Status: Clean X-Spam-Score: 0.2 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RCVD_ILLEGAL_IP=0.234 Subject: Re: LF: Antennas Content-Type: multipart/alternative; boundary="----=_NextPart_000_00BB_01CCCA1F.24D1FC00" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_40_50,HTML_MESSAGE, MISSING_OUTLOOK_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-SCOLL-SCORE: 0:2:406796192:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d600e4f0308cf1630 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_00BB_01CCCA1F.24D1FC00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Yes , S/N ... that is the bottom line , and with low noise = amplification , it makes no sense to deploy a probe bigger than = required for the job in hand .... surely the more Ae before the = Amp the more random noise it will produced ... ? G..=20 From: Rik Strobbe=20 Sent: Tuesday, January 03, 2012 12:38 PM To: rsgb_lf_group@blacksheep.org=20 Subject: RE: LF: Antennas Depends on how "gain" is defined. Larges antennas pick up more signal, = but also more noise.=20 It is the signal to noise ratio that is important, and this is no better = than with smaller antennas. With a large antenna a signal will be S9 and noise at S7. With a small = antenna the same signal will be S3 with noise at S1. In both cases SNR = is the same.=20 73, Rik ON7YD - OR7T -------------------------------------------------------------------------= ------- Van: owner-rsgb_lf_group@blacksheep.org = [owner-rsgb_lf_group@blacksheep.org] namens mal hamilton = [g3kevmal@talktalk.net] Verzonden: dinsdag 3 januari 2012 11:57 Aan: rsgb_lf_group@blacksheep.org Onderwerp: Re: LF: Antennas Like you say with the larger antennas Attenuation is needed there is so = much more gain over the smaller variety. My antennas both on LF es MF have attenuation control to reduce the = gain, a good position to be in I suppose. g3kev ----- Original Message -----=20 From: Rik Strobbe=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Tuesday, January 03, 2012 10:48 AM Subject: RE: LF: Antennas Hello Doug, over the past decade I have tested small loop antennas, a miniwhip = (PA0RDT) and a "big" transmitting antenna for receiving purposes and = found that each of them has its own advantages, as well on 137kHz as on = 500kHz. Loop antenna Advantages: - very frequency selective, can be useful to attenuate broadcast - 8-shaped pattern can be useful to null out QRM sources - if large enough you don't need a pre-amp - you can move the loop around your property to find the best (now = noise) location Disadvantages: - not omnidirectional, so you might need to rotate the loop=20 - single band antenna Miniwhip: Advantages: - broadband, can be used from (V)LF to HF - omnidirectional - you can move the loop around your property to find the best (now = noise) location Disadvantages: - pre-amp (built in), so you need to feed it with a DC voltage. This = has to be done with some care as it can introduce QRM. - broadband so your RX needs to be able to handle the all signals. Can = be solved by a BPF in front of the RX. "Big" TX antenna (Marconi): Advantes: - readily available if you also TX on 137/500kHz - no TX/RX antenna switching if you also TX on 137/500kHz - no pre-amp needed (in contradiction, often you will need an = attenuator). - some frequency selectivity, but not as good as a loop Disadvantages: - big, often not worth the effort if you only want to RX - cannot be moved around to minimize QRM Conclusion: If you have a TX antenna and the local QRM is not too bad you can use = it as RX antenna, so no need for an additional RX antenna. If you use a = loop RX antenna it should be at sufficient distance from your TX = antenna, otherwise it will pick up all the QRM from the TX antenna. I = did not notice that effect with the miniwhip. If you want to RX only a loop or miniwhip seems the best (most = economical) option. I compared the miniwhip and my TX antenna on many occasions and could = not notice a significant difference (as RX antenna).=20 During the winter 2010-2011 Canadian and US beacons were copied = regulary with good (audible) signals on 500kHz. 73, Rik ON7YD - OR7T -------------------------------------------------------------------------= ----- Van: owner-rsgb_lf_group@blacksheep.org = [owner-rsgb_lf_group@blacksheep.org] namens Douglas D. Williams = [kb4oer@gmail.com] Verzonden: maandag 2 januari 2012 22:53 Aan: rsgb_lf_group@blacksheep.org Onderwerp: Re: LF: Antennas Mal, you lost me on this one. Are you suggesting I (or we.....here in = North America) erect large verticals, inv L systems, Rhombics, and V = beams in order to receive EU LF signals? I thought I was doing pretty well with my micro RX antenna! Doug KB4OEr =20 On Mon, Jan 2, 2012 at 6:28 PM, mal hamilton = wrote: LF es MF Reports from across the pond and other DX locations as far as = Tenneesee and Kansas using micro probe antennas are great for QRSS = speeds but not suitable for audio reception. Take 160 metres for example where it is normal to work world wide on = cw but antennas in use are large verticals, inv L systems, Rhombics and = V beams, therefore to have any chance of receiving signals at audio = level on LF or MF large antennas of the calibre used on 160 metres are = necessary. As well as TX at this QTH I also use large arrays for RX and often = hear signals from NA that would not be audible with small loops, micro = probes or ferrite sticks Recently on 500 I was able to copy a W stn 579 but a DL stn copied = only on screen, when I asked what strength the signal was I got no = reply!!!!!!!!!!!!! using a micro probe antenna. If a proper large antenna system is not used on LF es MF then there = is virtually NIL chance of an audio report from across the pond for EU = stns es vice versa Back some years ago I had audio reports from the Boston area but the = antennas were proper wire arrays as used on 160 metres Small hand held antennas are fine for High Power BC strength = signals but not for low power amateur signals to be heard No commercial LF/MF station would even consider an antenna of the = micro variety. When I was in the business some years ago on LF/MF Rhombics and = V-Beams were the norm de mal/g3kev ------=_NextPart_000_00BB_01CCCA1F.24D1FC00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Yes  , S/N ... that is the  bottom  line  , = and =20 with  low  noise  amplification  ,  it  = makes=20 no  sense  to  deploy a  probe   bigger = than =20 required for  the job  in hand .... surely  the  = more =20 Ae  before  the Amp the  more  random  = noise =20 it  will produced  ... ?
 
G..

From: Rik Strobbe
Sent: Tuesday, January 03, 2012 12:38 PM
To: rsgb_lf_group@blacksheep.org= =20
Subject: RE: LF: Antennas

Depends on how "gain" is=20 defined. Larges antennas pick = up more=20 signal, but also more noise. =
It is the signal to noise=20 ratio that is important, and this=20 is no better than with = smaller=20 antennas.
With a large antenna=20 a signal will be S9=20 and noise at S7. With a small = antenna=20 the same signal will be&n= bsp;S3 with noise=20 at S1. In both cases SNR is the=20 same. 
 
73, Rik  ON7YD -=20 OR7T
 
Van: owner-rsgb_lf_group@bl= acksheep.org=20 [owner-rsgb_lf_group@blacksheep.org] namens mal hamilton=20 [g3kevmal@talktalk.net]
Verzonden: dinsdag 3 januari 2012=20 11:57
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: = Re: LF:=20 Antennas

Like you say with the larger antennas = Attenuation is=20 needed there is so much more gain over the smaller variety.
My antennas both on LF es MF = have attenuation=20 control  to reduce the gain, a good position to be in I=20 suppose.
g3kev
 
----- Original Message -----
From: Rik Strobbe
Sent: Tuesday, January 03, 2012 = 10:48=20 AM
Subject: RE: LF: Antennas

Hello Doug,
 
over the past decade I have tested small = loop=20 antennas, a miniwhip (PA0RDT) and a=20 "big" transmitting=20 antenna for receiving purposes=20 and found that each = of them=20 has its own=20 = advantages, as well on 137kHz= =20 as on 500kHz.
 
Loop antenna
Advantages:
- very frequency=20 selective, can be useful=20 to attenuate broadcast
=
- 8-shaped pattern can be useful=20 to null out QRM sources
=
- if large enough you don't need=20 a pre-amp
- you can move the=20 loop around your property=20 to find the best (now noise) = location
Disadvantages:
- not=20 = omnidirectional, so you might&= nbsp;need=20 to rotate the loop
- single band antenna
 
Miniwhip:
Advantages:
-=20 = broadband, can be used fr= om=20 (V)LF to HF
- omnidirectional
- you can move the=20 loop around your property=20 to find the best (now noise) = location
Disadvantages:
- pre-amp (built=20 in), so you need=20 to feed it with a DC=20 voltage. This has=20 to be done with some = care=20 as it can introduce = QRM.
=
- broadband so your RX needs=20 to be able to handle the all=20 = signals. Can be solved by= =20 a BPF in front of the RX.
 
"Big" TX antenna (Marconi):
Advantes:
=
- readily available if you<= A> also TX on=20 137/500kHz
- no TX/RX=20 = antenna switching if you also=  TX on=20 137/500kHz
- no pre-amp needed (in=20 = contradiction, often you will&= nbsp;need an=20 attenuator).
- some frequency=20 selectivity, but not = as good as a=20 loop
Disadvantages:
- big, often not worth=20 the effort if you only = want to=20 RX
=
- cannot be moved around= =20 to minimize QRM
 
Conclusion:
If you have a TX antenna and=20 the local QRM = is not too=20 bad you can use it=20 as RX=20 = antenna, so no need for&n= bsp;an additional RX=20 antenna. If you use a = loop RX=20 antenna it should be=20 = at sufficient distance from your=  TX=20 = antenna, otherwise it will pick<= A>=20 up all the QRM from the TX = antenna.=20 I did not notice that=20 effect with the miniwhip.
If you want=20 to RX only a=20 loop or miniwhip seems the = best (most=20 economical) option.
I compared = the miniwhip=20 and my TX = antenna on many=20 occasions and could not notice a=20 significant difference (as RX antenna). =
During the winter=20 2010-2011 Canadian and=20 = US beacons were copied regulary<= A> with good=20 (audible) signals on=20 500kHz.
 
73, = Rik  ON7YD -=20 OR7T
Van:=20 owner-rsgb_lf_group@blacksheep.org = [owner-rsgb_lf_group@blacksheep.org]=20 namens Douglas D. Williams = [kb4oer@gmail.com]
Verzonden:=20 maandag 2 januari 2012 22:53
Aan:=20 rsgb_lf_group@blacksheep.org
Onderwerp: Re: = LF:=20 Antennas

Mal, you lost me on this = one.=20 Are you suggesting I (or = we.....here=20 in North = America) erect large=20 verticals, inv L systems, Rhombics, = and=20 V beams in order to receive EU LF=20 signals?
 
 
I thought I=20 = was doing pretty well with my=20 micro RX antenna!
 
 
Doug KB4OEr
 


 
On Mon, Jan 2, 2012 at = 6:28 PM,=20 mal hamilton <g3kevmal@talktalk.net>=20 wrote:
LF es=20 MF
Reports from across = the pond=20 and other DX locations=20 as far as Tenneesee and = Kansas using=20 micro probe antennas=20 = are great for QRSS speeds=  but not suitable for=20 audio reception.
Take 160 metres for = ;example where it=20 is normal=20 = to work world wide on&nbs= p;cw but antennas=20 in use are large = verticals, inv L=20 systems, Rhombics and V=20 beams, therefore to=20 have any chance=20 of receiving signals at audio=20 = level on LF or MF la= rge antennas=20 of the calibre used on=20 160 metres are necessary.
As well as TX=20 at this QTH=20 = I also use large arrays&n= bsp;for RX=20 = and often hear signals from=20 = NA that would not be = ;audible with small=20 loops, micro probes or ferrite = sticks
Recently on=20 500 I was able to copy a W stn=20 579 but a=20 = DL stn copied only on=20 screen, when=20 I asked what strength=20 the signal was I got no=20 reply!!!!!!!!!!!!! using a = micro probe=20 antenna.
If a=20 proper large antenna system=20 is not used on LF=20 es MF then there=20 is virtually NIL chance=20 of an audio report from across = the=20 pond for EU stns es vice=20 versa
Back some years ago = I had=20 audio reports from the = Boston area but=20 the antennas were=20 proper wire arrays=20 as used on 160 metres
Small hand=20 held antennas are fine for High=20 = Power  BC strength signals = but not for=20 low power amateur signals to be=20 heard
No commercial LF/MF = station would=20 even consider an antenna of the micro=20 variety.
When I = was in the=20 = business some years ago on=20 LF/MF Rhombics = and V-Beams were=20 the norm
de mal/g3kev
 
 
 
 

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