Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dh01.r1000.mx.aol.com (Internet Inbound) with ESMTP id C8DE73800009A; Tue, 3 Jan 2012 10:10:11 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Ri5zK-0000uI-F3 for rs_out_1@blacksheep.org; Tue, 03 Jan 2012 15:09:18 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Ri5zJ-0000u9-K0 for rsgb_lf_group@blacksheep.org; Tue, 03 Jan 2012 15:09:17 +0000 Received: from rhcavuit01.kulnet.kuleuven.be ([134.58.240.129] helo=cavuit01.kulnet.kuleuven.be) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Ri5zH-0001fM-Pt for rsgb_lf_group@blacksheep.org; Tue, 03 Jan 2012 15:09:17 +0000 X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-KULeuven-Scanned: Found to be clean X-KULeuven-ID: C4E87138073.A58BB X-KULeuven-Information: Katholieke Universiteit Leuven Received: from smtps02.kuleuven.be (smtpshost02.kulnet.kuleuven.be [134.58.240.75]) by cavuit01.kulnet.kuleuven.be (Postfix) with ESMTP id C4E87138073 for ; Tue, 3 Jan 2012 16:09:03 +0100 (CET) Received: from ICTS-S-HUB-N1.luna.kuleuven.be (icts-s-hub-n1.luna.kuleuven.be [10.112.9.11]) by smtps02.kuleuven.be (Postfix) with ESMTP id 8D506F3862 for ; Tue, 3 Jan 2012 16:09:03 +0100 (CET) Received: from ICTS-S-EXC2-CA.luna.kuleuven.be ([10.112.11.13]) by ICTS-S-HUB-N1.luna.kuleuven.be ([10.112.9.11]) with mapi; Tue, 3 Jan 2012 16:09:03 +0100 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" Date: Tue, 3 Jan 2012 16:09:03 +0100 Thread-Topic: LF: Antennas Thread-Index: AczKFszHP4dsbVduTWGkJxVhOzNssQAERLUq Message-ID: References: <008301ccc97c$51d9fcf0$0401a8c0@xphd97xgq27nyf>, ,<003501ccca06$6bdef490$0401a8c0@xphd97xgq27nyf> ,<4F02F9EA.1090101@iup.uni-heidelberg.de> In-Reply-To: <4F02F9EA.1090101@iup.uni-heidelberg.de> Accept-Language: nl-NL, nl-BE Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: nl-NL, nl-BE MIME-Version: 1.0 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: RE: LF: Antennas Content-Type: multipart/alternative; boundary="_000_BF4A524700075746A6467658DFC7102CB0B489A6C8ICTSSEXC2CAlu_" 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, TO_ADDRESS_EQ_REAL 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: 0:2:438423392:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d41154f031a53076d X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --_000_BF4A524700075746A6467658DFC7102CB0B489A6C8ICTSSEXC2CAlu_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Stefan, at certain moments the ongoing discussion reminds me of a (true ?) story: Some citizens were worried about a new high voltage overland power line clo= se to their homes. They complained with the minister of energy. The minister aranged a meeting with the CEO of the power company and asked = if they could use much lower voltages on their overland lines. The CEO resp= onded that this was not possible as a lower voltage would dramaticaly incre= ase the losses. Next the minister asked why that would happen, and the answer was "due to O= hm's law". With a big smile on his face the minister said that it would be easy to sol= ve this problem as he would take the necessary steps in parliament to ammen= d Ohm's law so it would no longer be applicable to overland power lines ... 73, Rik ON7YD - OR7T ________________________________ Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org= ] namens Stefan Sch=E4fer [Stefan.Schaefer@iup.uni-heidelberg.de] Verzonden: dinsdag 3 januari 2012 13:51 Aan: rsgb_lf_group@blacksheep.org Onderwerp: Re: LF: Antennas Hi Rik, Am 03.01.2012 13:38, schrieb Rik Strobbe: Depends on how "gain" is defined. Larges antennas pick up more signal, but = also more noise. It is the signal to noise ratio that is important, and this is no better th= an with smaller antennas. With a large antenna a signal will be S9 and noise at S7. With a small ante= nna the same signal will be S3 with noise at S1. In both cases SNR is the s= ame. This is exactly the thing that he never will understand. Often discussed an= d somehow logical, anyway. This is why he says that a small antenna is wors= e, since he runs a RX that needs a high signal input level. Thus a small an= tenna, 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 muc= h 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 ----- From: Rik Strobbe To: rsgb_lf_group@blacksheep.org 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 eac= h 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) l= ocation Disadvantages: - not omnidirectional, so you might need 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 to find the best (now noise) l= ocation 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 s= olved 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 eff= ect 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 n= otice a significant difference (as RX antenna). During the winter 2010-2011 Canadian and US beacons were copied regulary wi= th 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 or= der to receive EU LF signals? I thought I was doing pretty well with my micro RX antenna! Doug KB4OEr On Mon, Jan 2, 2012 at 6:28 PM, mal hamilton @talktalk.net> 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 suitab= le 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 M= F 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 sig= nals from NA that would not be audible with small loops, micro probes or fe= rrite 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 virt= ually NIL chance of an audio report from across the pond for EU stns es vic= e versa Back some years ago I had audio reports from the Boston area but the antenn= as were proper wire arrays as used on 160 metres Small hand held antennas are fine for High Power BC strength signals but n= ot for low power amateur signals to be heard No commercial LF/MF station would even consider an antenna of the micro var= iety. When I was in the business some years ago on LF/MF Rhombics and V-Beams wer= e the norm de mal/g3kev --_000_BF4A524700075746A6467658DFC7102CB0B489A6C8ICTSSEXC2CAlu_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Stefan,
 
at certain moments the ongoing&nbs= p;discussion reminds me of a (true ?) story:
Some citizens were worried&= nbsp;about a new high voltage overland power=  line close to their homes. They c= omplained with the minister of energy.
The minister aranged a meeting with the C= EO of the power company and asked if=  they could use much&nb= sp;lower voltages on their overland<= /a> lines. The CEO responded that this was not possible as a lower voltage&nb= sp;would dramaticaly increase the losses<= /a>.
Next the minister asked why t= hat would happen, and the answer was &q= uot;due to Ohm's law".
With a big smile on his face the minister said that it w= ould be easy to solve this = problem as he would take the&nbs= p;necessary steps in parliament to ammend Ohm's law so&nbs= p;it would no longer be<= /a> applicable to overland power lines = ...
 
73, Rik=   ON7YD - OR7T
 
Van: owner-rsgb_l= f_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Stefan S= ch=E4fer [Stefan.Schaefer@iup.uni-heidelberg.de]
Verzonden: dinsdag 3 januari 2012 13:51
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: Antennas

Hi Rik,

Am 03.01.2012 13:38, schrieb Rik Strobbe:
Depends on how "gain" is defined. Larges = ;antennas pick up more signal, but also more noise.
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 si= gnal will be S3 with noise at S1. In both cas= es SNR is the same.

This is exactly the thing that he never will understand. Often discussed an= d somehow logical, anyway. This is why he says that a small antenna is wors= e, since he runs a RX that needs a high signal input level. Thus a small an= tenna, 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@b= lacksheep.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 atten= uation control  to reduce the gain, a good position to be in I suppose= .
g3kev
 
----- Original Message -----
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&nb= sp;miniwhip (PA0RDT) and a "big" transmitting antenna f= or receiving purposes and found that each of = them has its own advantages, as well on 137kH= z as on 500kHz.
 
Loop antenna
Advantages:
- very frequency selective, can be useful to&= nbsp;attenuate broadcast
- 8-shaped pattern can be useful to null= out QRM sources
- if large enough you don't need a pre-a= mp
- you can move the loop around your property = to find the best (now noise) location
Disadvantages:
- not omnidirectional, so you might need to&n= bsp;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 = to find the best (now noise) location
Disadvantages:
- pre-amp (built in), so you need to feed&nbs= p;it with a DC voltage. This has to be done w= ith 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,&nb= sp;so no need for an additional RX antenna.&n= bsp;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 e= conomical) option.
I compared the miniwhip and&nbs= p;my TX antenna on many occasions and could not&nb= sp;notice a significant difference (as RX antenna).
During the w= inter 2010-2011 Canadian and US beacons were copied reg= ulary with good (audible) signals on 500kHz.
 
73, Rik  ON7YD - OR= 7T
Van:= owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@b= lacksheep.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 suggest= ing I (or we.....here in North America) erect large vertical= s, inv L systems, Rhombics, and V beams in order to receive = EU LF signals?
 
 
I thought I was doing pretty well with m= y micro RX antenna!
 
 
Doug KB4OEr
 


 
On Mon, Jan 2, 2012 at 6:28 PM, mal ha= milton <g3kevmal@talktalk.net> wrote:
LF es MF<= /div>
Reports from across the pond and o= ther DX locations as far as Tenneesee and Kansas u= sing micro probe antennas are great for QRSS = speeds but not suitable for audio reception.
Take 160 me= tres for example where it is normal to work&n= bsp;world wide on cw but antennas in use are&= nbsp;large verticals, inv L systems, Rhombics and V beams, t= herefore to have any chance of receiving signals at aud= io level on LF or MF large antennas of the = ;calibre used on 160 metres are necessary.
As well as TX at this QTH I&n= bsp;also use large arrays for RX and often&nb= sp;hear signals from NA that would not be&nbs= p;audible with small loops, micro probes or ferrite sti= cks
Recently on 500 = I was able to copy a W stn 579 but a DL stn c= opied only on screen, when I asked what stren= gth 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 re= port from across the pond for EU stns es vice vers= a
Back some years ago I had audio re= ports from the Boston area but the antennas were p= roper wire arrays as used on 160 metres
Small hand held&= nbsp;antennas are fine for High Power  BC strength=  signals but not for low power amateur signals to&= nbsp;be heard
No commercial LF/MF station would even = consider an antenna of the micro variety.
When I was in th= e business some years ago on LF/MF Rhombics and&nb= sp;V-Beams were the norm
de mal/g3kev
 
 
 
 

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