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 60BC338000081; Tue, 3 Jan 2012 09:05:10 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Ri4yU-0008Uu-BJ for rs_out_1@blacksheep.org; Tue, 03 Jan 2012 14:04:22 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Ri4yT-0008Ul-G5 for rsgb_lf_group@blacksheep.org; Tue, 03 Jan 2012 14:04:21 +0000 Received: from out1.ip03ir2.opaltelecom.net ([62.24.128.239]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Ri4yR-0000vI-Kp for rsgb_lf_group@blacksheep.org; Tue, 03 Jan 2012 14:04:21 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AmUQALAKA09cF/hn/2dsb2JhbABDggVJqhGBBoFtBQEBBQgBAQNJAg4GCg4BAQMFAgEDEQQBAQoXDhQBBAgSBhYIBhMKAQICAQGHa7UWjA8EglqFKoUsAZJAh0U X-IronPort-AV: E=Sophos;i="4.71,450,1320624000"; d="scan'208,217";a="371034628" Received: from host-92-23-248-103.as13285.net (HELO xphd97xgq27nyf) ([92.23.248.103]) by out1.ip03ir2.opaltelecom.net with SMTP; 03 Jan 2012 14:04:04 +0000 Message-ID: <004601ccca20$8aa7d1c0$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: <008301ccc97c$51d9fcf0$0401a8c0@xphd97xgq27nyf>, ,<003501ccca06$6bdef490$0401a8c0@xphd97xgq27nyf> <4F02F9EA.1090101@iup.uni-heidelberg.de> Date: Tue, 3 Jan 2012 14:03:57 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: Antennas Content-Type: multipart/alternative; boundary="----=_NextPart_000_0041_01CCCA20.890433E0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_30_40,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-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:458992544:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d600e4f030b161c7d 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_0041_01CCCA20.890433E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable This is NOT the case at my QTH. The signal over noise is excellent = because I live in a QUIET location S9 signal with virtually no NOISE from the large antenna.=20 Why do commercial receiving stations use large antenna farms out in the = countryside ?? They do not use ferrite sticks or micro probes If you have always lived in an Urban environment with lots of noise then = you do not understand what I am talking about. Go out into the countryside, put up a large antenna array and compare it = against pocket size antennas, then you will be in a position to comment. = If International commercial and coastal receiving radio stations could = use Ferrite sticks, micro probes they would not go to the vast expense = of installing large wire arrays. Out in Rural areas large antennas equals big gain and very little noise = whereas in Urban areas what ever sort of antenna you use there is likely = to be a noise problem. One other point at my QTH there are no overhead wires in the immediate = vicinity nor as far as I can see looking for miles across the = countryside to cause noise pollution. A large antenna at your qth might capture more noise than signal, hardly = the place to live for a LF experimenter!! g3kev =20 ----- Original Message -----=20 From: Stefan Sch=E4fer=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Tuesday, January 03, 2012 12:51 PM Subject: Re: LF: Antennas Hi Rik, Am 03.01.2012 13:38, schrieb Rik Strobbe:=20 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. This is exactly the thing that he never will understand. Often = discussed and somehow logical, anyway. This is why he says that a small = antenna is worse, since he runs a RX that needs a high signal input = level. Thus a small antenna, e.g. a ferrite antenna without a suitable = preamp, gives poor results.... 73, Stefan 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_0041_01CCCA20.890433E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
This is NOT the case at my QTH. The signal over = noise is=20 excellent because I live in a QUIET location  S9 signal with = virtually no=20 NOISE
from the large antenna.
Why do commercial receiving stations use large = antenna=20 farms out in the countryside ?? They do not use ferrite sticks or micro=20 probes
If you have always lived in an = Urban environment with=20 lots of noise then you do not understand what I am talking = about.
Go out into the countryside, put up a large = antenna array=20 and compare it against pocket size antennas, then you will be in a = position to=20 comment.
If International commercial and coastal = receiving=20 radio stations could use Ferrite sticks, micro probes they would not go = to=20 the vast expense of installing large wire arrays.
Out in Rural areas large antennas equals = big gain and=20 very little noise whereas in Urban areas what ever sort of antenna you = use there=20 is likely to be a noise problem.
One other point at my QTH there are no overhead=20 wires in the immediate vicinity nor as far as I can see looking for = miles=20 across the countryside to cause noise pollution.
A large antenna at your qth might capture more = noise than=20 signal, hardly the place to live for a LF experimenter!!
g3kev
 
 
 
----- Original Message -----
From:=20 Stefan = Sch=E4fer
Sent: Tuesday, January 03, 2012 = 12:51=20 PM
Subject: Re: LF: Antennas

Hi Rik,

Am 03.01.2012 13:38, schrieb Rik = Strobbe:=20
Depends on how "gain" is=20 defined. Larges antennas pick up more=20 signal, but also more noise.
It is the signal to noise ratio that is = important,=20 and this is no better than with smaller=20 antennas.
With a large antenna = a signal will be S9=20 and noise at S7. With a small antenna=20 = the same signal will be S3 with noise = at=20 S1. In both cases SNR is the = same.

This=20 is exactly the thing that he never will understand. Often discussed = and=20 somehow logical, anyway. This is why he says that a small antenna is = worse,=20 since he runs a RX that needs a high signal input level. Thus a small = antenna,=20 e.g. a ferrite antenna without a suitable preamp, gives poor=20 results....

73, Stefan



 
 
73, Rik  ON7YD - = OR7T
 
Van: owner-rsgb_lf_group@bl= acksheep.org=20 [owner-rsgb_lf_group@bl= acksheep.org]=20 namens mal hamilton [g3kevmal@talktalk.net]
Ve= rzonden:=20 dinsdag 3 januari 2012 11:57
Aan: rsgb_lf_group@blacksheep.org=
Onderwerp:=20 Re: LF: 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=20 have attenuation control  to reduce the gain, a good = position to=20 be in I suppose.
g3kev
 
-----=20 Original Message -----
From:=20 Rik=20 Strobbe To:=20 rsgb_lf_group@blacksheep.org Sent:=20 Tuesday, January 03, 2012 10:48 AM Subject:=20 RE: LF: Antennas

Hello Doug,
 
over the past decade I have tested small loop = antennas,=20 a miniwhip (PA0RDT) and a "big" transmitting=20 antenna for receiving purposes=20 and found that each of them = has its own=20 advantages, as well on 137kHz as on = 500kHz.
 
Loop antenna
Advantages:
- very frequency = 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 a=20 pre-amp
- you can move the = loop around your property=20 to find the best (now noise) location
Disadvantages:
- not = omnidirectional, so you might need=20 to rotate the loop
- single band antenna
 
Miniwhip:
Advantages:
- broadband, can be used from (V)LF to = HF
- omnidirectional
- you can move the = loop around your property=20 to find the best (now noise) location
Disadvantages:
- pre-amp (built in), so you need=20 to feed it with a DC 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 a BPF in front = of the=20 RX.
 
"Big" TX antenna (Marconi):
Advantes:
=
- readily available if you also TX&nbs= p;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 need an=20 attenuator).
- some frequency selectivity, but not=20 as good as a loop
Disadvantages:
- big, often not worth=20 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=20 is not too bad you can use it = as RX=20 = antenna, so no need for 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 up all=20 the QRM from the TX antenna.=20 I did not notice that effect with the=20 miniwhip.
If you want = to RX only a=20 loop or miniwhip seems the best (most = economical)=20 option.
I compared the miniwhip=20 and my TX antenna on many occasions=20 and could not notice a significant difference=20 (as RX antenna).
During the winter=20 2010-2011 Canadian and=20 = US beacons were copied regulary with good=20 (audible) signals on 500kHz.
 
73, = Rik  ON7YD -=20 OR7T
Van: owner-rsgb_lf_group@bl= acksheep.org=20 [owner-rsgb_lf_group@bl= acksheep.org]=20 namens Douglas D. Williams [kb4oer@gmail.com]
Verzonden:=20 maandag 2 januari 2012 22:53
Aan: rsgb_lf_group@blacksheep.org=
Onderwerp:=20 Re: LF: Antennas

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


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

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