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The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Antenna efficiency is significantly lower, no question. It is not going to be a walk in the park to make possible T/A crossings on a regular basis if at all. Time will certainly tell. I won't give up easily-Bob [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [65.55.116.27 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (rjraide[at]hotmail.com) -0.0 SPF_PASS SPF: sender matches SPF record -0.0 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 7c995d39cde70605aa76dd18810a4256 Content-Type: multipart/alternative; boundary="_9cb00f44-1806-40c5-a64d-650f8ad7cdbd_" Subject: RE: LF: Re: U.S. VLF License WH2XBA X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=FORGED_HOTMAIL_RCVD, 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 --_9cb00f44-1806-40c5-a64d-650f8ad7cdbd_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Antenna efficiency is significantly lower=2C no question. It is not going = to be a walk in the park to make possible T/A crossings on a regular basis = if at all. Time will certainly tell. I won't give up easily-Bob =20 > To: rsgb_lf_group@blacksheep.org > From: us66soft@aol.com > Date: Sat=2C 1 Mar 2014 21:15:16 -0500 > Subject: RE: LF: Re: U.S. VLF License WH2XBA >=20 > So far as the less robust reception I got this afternoon here in the=20 > middle of the continent=2C there are a couple of other factors to=20 > consider in addition to propagation. >=20 > Probably the biggest one is antenna efficiency. The frequency ratio=20 > from 74 kHz to 30 kHz is 2.46:1. Unless your antenna is significantly=20 > taller than for the other bands=2C that means the radiation resistance=20 > has diminished by the square of that ratio (a factor af about 6.08). =20 > At the very best=2C your loading coil loss and ground system resistance=20 > might remain about the same=2C but could very well increase (such as if=20 > the increased skin depth takes return currents lower into the earth=2C=20 > into a less conductive rock layer). So=2C I would expect overall antenna= =20 > loss has increased significantly--perhaps by 15 or 16 dB. >=20 > Second=2C I'm using the receiver outside its rated tuning range=2C by mea= ns=20 > of lower sideband mode. My 250 Hz IF filter helps minimize the static=20 > levels seen by the receiver=2C but seems to have a few dB additional loss= =20 > when switched in the SSB chain. I discovered this a couple of months=20 > ago when I was testing various ways of copying your WSPR-2 signal at=20 > LF. Decoding was more effective when I used the narrow filter with=20 > upper sideband rather than the 1.8 kHz SSB filter=2C but was even _more_= =20 > effective when the narrow filter was in the CW chain with its normal=20 > BFO offset. Therefore=2C my receiving setup is likely to be a few dB=20 > less sensitive as well when working in this non-standard fashion. >=20 > On the positive side=2C just before I returned to town to check e-mail=2C= =20 > it appeared that somewhat improved nighttime propagation might be=20 > kicking in. We'll know more in a couple of hours. >=20 > John >=20 > -----Original Message----- > From: Bob Raide > To: rsgb_lf_group > Sent: Sat=2C Mar 1=2C 2014 3:45 pm > Subject: RE: LF: Re: U.S. VLF License WH2XBA >=20 > Alan=3B > I am noticing exactly that-groundwave not that good at 29 kHz. Much=20 > better at 137 or even 74. Just got report from Kansas where I always=20 > put good daytime sigs in on 137-74. Got lot to learn about this VLF=20 > stuff-Bob >=20 > - - - - - >=20 > From: alan.melia@btinternet.com > To: rsgb_lf_group@blacksheep.org > Date: Sat=2C 1 Mar 2014 21:15:41 +0000 > Subject: Re: LF: Re: U.S. VLF License WH2XBA >=20 > Hi Bob if you mean "skywave" or ionospheric returns? that occurs day=20 > and night at LF and VLF the skywave is weaker in daytime at LF due to a=20 > portion of absorbing D-lyer below the apparent reflection height=2C also= =20 > at VLF but less so. At the powers we use the ground wave probably does=20 > not go very far. I think the two are about the same strength at around=20 > 400miles then the skywave predominates. It may be less with amateir=20 > antennas because a lot more of the signal is lanuched at higher angles=20 > that would be the case for big antenna on Mil sites. >=20 > I think there is some confusion about VLF being "all groundwave". Many=20 > of these ideas were formed in the days before Heaviside and Appleton.=20 > Ionospheric return is fom the D-layer in daytime (with some absorption)=20 > and by the lower E-layer at night. >=20 > Paul Nicholson has front-ended some Mil propagtion software for VLF=20 > called LWPC you can tell its the "real stuff it was written in Fortran=20 > :-)) > Single shot strengths are calculated for the date and time entered so=20 > you can see diurnal effects. I have not tried it at very short range=20 > but it certainly models he day-night transition quite well > It is at http://abelian.org/lwpc/ >=20 > Best Wishes for Good VLF DX > Alan > G3NYK >=20 >=20 >=20 >=20 >=20 = --_9cb00f44-1806-40c5-a64d-650f8ad7cdbd_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Antenna efficiency is =3Bsig= nificantly lower=2C no question. =3B It is not going to be a walk in th= e park to make =3Bpossible T/A crossings on a regular basis if at all.&= nbsp=3B Time will certainly tell. =3B I won't give up easily-Bob
&nb= sp=3B
>=3B To: rsgb_lf_group@blacksheep.org
>=3B From: us66s= oft@aol.com
>=3B Date: Sat=2C 1 Mar 2014 21:15:16 -0500
>=3B Subj= ect: RE: LF: Re: U.S. VLF License WH2XBA
>=3B
>=3B So far as the= less robust reception I got this afternoon here in the
>=3B middle o= f the continent=2C there are a couple of other factors to
>=3B consid= er in addition to propagation.
>=3B
>=3B Probably the biggest on= e is antenna efficiency. The frequency ratio
>=3B from 74 kHz to 30= kHz is 2.46:1. Unless your antenna is significantly
>=3B taller tha= n for the other bands=2C that means the radiation resistance
>=3B has= diminished by the square of that ratio (a factor af about 6.08).
>= =3B At the very best=2C your loading coil loss and ground system resistance=
>=3B might remain about the same=2C but could very well increase (su= ch as if
>=3B the increased skin depth takes return currents lower in= to the earth=2C
>=3B into a less conductive rock layer). So=2C I wou= ld expect overall antenna
>=3B loss has increased significantly--perh= aps by 15 or 16 dB.
>=3B
>=3B Second=2C I'm using the receiver o= utside its rated tuning range=2C by means
>=3B of lower sideband mode= . My 250 Hz IF filter helps minimize the static
>=3B levels seen by = the receiver=2C but seems to have a few dB additional loss
>=3B when = switched in the SSB chain. I discovered this a couple of months
>=3B= ago when I was testing various ways of copying your WSPR-2 signal at
&= gt=3B LF. Decoding was more effective when I used the narrow filter with <= br>>=3B upper sideband rather than the 1.8 kHz SSB filter=2C but was even= _more_
>=3B effective when the narrow filter was in the CW chain wit= h its normal
>=3B BFO offset. Therefore=2C my receiving setup is lik= ely to be a few dB
>=3B less sensitive as well when working in this n= on-standard fashion.
>=3B
>=3B On the positive side=2C just befo= re I returned to town to check e-mail=2C
>=3B it appeared that somewh= at improved nighttime propagation might be
>=3B kicking in. We'll kn= ow more in a couple of hours.
>=3B
>=3B John
>=3B
>= =3B -----Original Message-----
>=3B From: Bob Raide <=3Brjraide@hotm= ail.com>=3B
>=3B To: rsgb_lf_group <=3Brsgb_lf_group@blacksheep.or= g>=3B
>=3B Sent: Sat=2C Mar 1=2C 2014 3:45 pm
>=3B Subject: RE:= LF: Re: U.S. VLF License WH2XBA
>=3B
>=3B Alan=3B
>=3B I a= m noticing exactly that-groundwave not that good at 29 kHz. Much
>= =3B better at 137 or even 74. Just got report from Kansas where I always <= br>>=3B put good daytime sigs in on 137-74. Got lot to learn about this = VLF
>=3B stuff-Bob
>=3B
>=3B - - - - -
>=3B
>= =3B From: alan.melia@btinternet.com
>=3B To: rsgb_lf_group@blacksheep.= org
>=3B Date: Sat=2C 1 Mar 2014 21:15:41 +0000
>=3B Subject: Re:= LF: Re: U.S. VLF License WH2XBA
>=3B
>=3B Hi Bob if you mean "s= kywave" or ionospheric returns? that occurs day
>=3B and night at LF = and VLF the skywave is weaker in daytime at LF due to a
>=3B portion = of absorbing D-lyer below the apparent reflection height=2C also
>=3B= at VLF but less so. At the powers we use the ground wave probably does >=3B not go very far. I think the two are about the same strength at aro= und
>=3B 400miles then the skywave predominates. It may be less with = amateir
>=3B antennas because a lot more of the signal is lanuched at= higher angles
>=3B that would be the case for big antenna on Mil sit= es.
>=3B
>=3B I think there is some confusion about VLF being "a= ll groundwave". Many
>=3B of these ideas were formed in the days befo= re Heaviside and Appleton.
>=3B Ionospheric return is fom the D-layer= in daytime (with some absorption)
>=3B and by the lower E-layer at n= ight.
>=3B
>=3B Paul Nicholson has front-ended some Mil propagti= on software for VLF
>=3B called LWPC you can tell its the "real stuf= f it was written in Fortran
>=3B :-))
>=3B Single shot strengths= are calculated for the date and time entered so
>=3B you can see diu= rnal effects. I have not tried it at very short range
>=3B but it cer= tainly models he day-night transition quite well
>=3B It is at http://= abelian.org/lwpc/
>=3B
>=3B Best Wishes for Good VLF DX
>= =3B Alan
>=3B G3NYK
>=3B
>=3B
>=3B
>=3B
>= =3B
= --_9cb00f44-1806-40c5-a64d-650f8ad7cdbd_--