Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-da04.r1000.mx.aol.com (Internet Inbound) with ESMTP id 74ED53800008E; Tue, 3 Jan 2012 07:39:30 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Ri3dA-0007ak-8a for rs_out_1@blacksheep.org; Tue, 03 Jan 2012 12:38:16 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Ri3d9-0007ab-Aw for rsgb_lf_group@blacksheep.org; Tue, 03 Jan 2012 12:38:15 +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 1Ri3d7-0008W2-KZ for rsgb_lf_group@blacksheep.org; Tue, 03 Jan 2012 12:38:15 +0000 X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-KULeuven-Scanned: Found to be clean X-KULeuven-ID: 9D5D8138044.A7954 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 9D5D8138044 for ; Tue, 3 Jan 2012 13:38:06 +0100 (CET) Received: from ICTS-S-HUB-N2.luna.kuleuven.be (icts-s-hub-n2.luna.kuleuven.be [10.112.9.12]) by smtps02.kuleuven.be (Postfix) with ESMTP id 885B5F3862 for ; Tue, 3 Jan 2012 13:38:06 +0100 (CET) Received: from ICTS-S-EXC2-CA.luna.kuleuven.be ([10.112.11.13]) by ICTS-S-HUB-N2.luna.kuleuven.be ([10.112.9.12]) with mapi; Tue, 3 Jan 2012 13:38:06 +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 13:38:06 +0100 Thread-Topic: LF: Antennas Thread-Index: AczKBr47qUwQpfNjRQikPliux90cVgADG81m Message-ID: References: <008301ccc97c$51d9fcf0$0401a8c0@xphd97xgq27nyf>, ,<003501ccca06$6bdef490$0401a8c0@xphd97xgq27nyf> In-Reply-To: <003501ccca06$6bdef490$0401a8c0@xphd97xgq27nyf> 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_BF4A524700075746A6467658DFC7102CB0B489A6C6ICTSSEXC2CAlu_" 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_40_50,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: 0:2:392730656:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d404c4f02f70231c1 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --_000_BF4A524700075746A6467658DFC7102CB0B489A6C6ICTSSEXC2CAlu_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable 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. 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_BF4A524700075746A6467658DFC7102CB0B489A6C6ICTSSEXC2CAlu_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Depends on how "gain" = is defined. Larges antennas pick= up more signal, but also more noise.
It is the signal to noise ratio&nb= sp;that is important, and this is no be= tter 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. 
=  
73, Rik  ON7YD - OR7T=
 
Van: owner-rsgb_l= f_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens mal hami= lton [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 10:4= 8 AM
Subject: RE: LF: Antennas

Hello Doug,
 
over the past decade I have tested small loop = antennas, a miniwhip (PA0RDT) and a "big&quo= t; transmitting antenna for receiving&n= bsp;purposes and found that each= of them has its own advantages, as well on 137kHz<= /a> as on 500kHz.
 
Loop antenna
Advantages:
- very frequency selective, can=  be useful to attenuate broadc= ast
- 8-shaped pattern can be<= /a> useful to null out QRM sources
- if large enough you&= nbsp;don't need a pre-amp
- you can move the loop around&nbs= p;your property to find the best (now= noise) location
Disadvantages:
- not omnidirectional, so you might need to rotate the loop
- single band antenna
 
Miniwhip:
Advantages:
- broadband, can be used&nb= sp;from (V)LF to HF
- omnidirectional
- you can move the loop around&nbs= p;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 i= ntroduce QRM.
- broadband so your RX=  needs to be able to handle= the all signals. Can be solved&= nbsp;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 137/500= kHz
- no pre-amp needed (in contradict= ion, often you will need=  an attenuator).
- some frequency selectivity, but<= a> not as good as a loop
Disadvantages:
- big, often not worth the ef= fort if you only want to RX
- cannot be moved around to minimize QRM
 
Conclusion:
If you have a TX antenna and the l= ocal QRM is not too bad you=  can use it as RX an= tenna, so no need for = an additional RX antenna. If you use a loop RX<= /a> antenna it should be at suffic= ient distance from your TX<= a> antenna, otherwise it will = pick up all the QRM from the TX antenna. I did not notice<= a> that effect with the miniwhip.
= If you want to RX only a loop or miniwh= ip seems the best (most economical) option.
I compared the miniwhip<= a> and my TX antenna on many occasions and could not notice a = significant difference (as RX antenna).
During&nbs= p;the winter 2010-2011 Canadian and US beacons were=  copied regulary with good = (audible) signals on 500kHz.
 
73, Rik  ON7YD&nb= sp;- OR7T
Van:= owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksh= eep.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
 


 
On Mon, Jan 2, 2012 at 6:28 P= M, mal hamilton <g3kevmal= @talktalk.net> wrote:
LF es MF<= a>
Reports from across the p= ond and other DX locations as far<= a> as Tenneesee and Kansas using micro pro= be antennas are great for Q= RSS speeds but not suitable=  for audio reception.
Take 160&= nbsp;metres for example where&nb= sp;it is normal to work world&nb= sp;wide on cw but antennas<= a> in use are large verticals, inv L systems, Rhombics a= nd V beams, therefore to have any chanc= e of receiving signals at audio level o= n LF or MF large&nbs= p;antennas of the calibre used on 160 metres are necessary.
As well as TX at thi= s QTH I also use large arrays for RX and often&= nbsp;hear signals from NA that&n= bsp;would not be audible wi= th 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<= /a> on screen, when I asked what strength the signal was I got no reply!!= !!!!!!!!!!! using a micro probe antenna.
If a prop= er large antenna system is not used&nbs= p;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<= a> I had audio reports from the Boston area&nbs= p;but the antennas were proper wire<= /a> arrays as used on 160 metres=
Small han= d held antennas are fine for High Power &= nbsp;BC strength signals but&nbs= p;not for low power amateur signals to = be heard
No commercial LF/MF station would<= /a> even consider an antenna of the micro variety.
When I wa= s in the business some years ago o= n LF/MF Rhombics and V-Beams wer= e the norm
de mal/g3kev
 
 
 
 

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