Wasn't there an article in QST that expounded on the limited reality of NVIS.
As pointed out, most of us are NVIS on 40 and down anyway.
WL
----- towertalk-request@contesting.com wrote:
> Send TowerTalk mailing list submissions to
> towertalk@contesting.com
>
> To subscribe or unsubscribe via the World Wide Web, visit
> http://lists.contesting.com/mailman/listinfo/towertalk
> or, via email, send a message with subject or body 'help' to
> towertalk-request@contesting.com
>
> You can reach the person managing the list at
> towertalk-owner@contesting.com
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of TowerTalk digest..."
>
>
> Today's Topics:
>
> 1. NVIS (not exactly towers, but HF) (jimlux)
> 2. Re: NVIS (not exactly towers, but HF) (John Simmons)
> 3. Re: NVIS (not exactly towers, but HF) (jimlux)
> 4. Re: NVIS (not exactly towers, but HF) (Rob Atkinson)
> 5. Re: NVIS (not exactly towers, but HF) (jimlux)
> 6. Re: NVIS (not exactly towers, but HF) (Gene Smar)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 8 Jun 2020 11:02:53 -0700
> From: jimlux <jimlux@earthlink.net>
> To: towertalk <towertalk@contesting.com>
> Subject: [TowerTalk] NVIS (not exactly towers, but HF)
> Message-ID: <68dc58ff-8aad-9e26-a6ff-61c1df21b2bc@earthlink.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> I guess if you have a tower, you're not so interested in NVIS <grin>
> Interesting paper (behind IEEE paywall unfortunately) in this month's
> Antennas and Propagation Magazine. The authors have a series of papers
> over the past few years of interest, looking at various performance factors.
>
>
> P. J. Coetzee and W. P. du Plessis, "Performance Limiters of
> Near-Vertical-Incidence Skywave Propagation: A Scientific Approach," in
> IEEE Antennas and Propagation Magazine, vol. 62, no. 3, pp. 39-44, June
> 2020, doi: 10.1109/MAP.2019.2943313.
>
>
> Abstract:
> Near-vertical-incidence skywave (NVIS) propagation is defined as
> providing continuous coverage from nearly 0 km (just beyond the line of
> sight) to a couple hundred kilometers from the transmitter with no skip
> or dead zones. NVIS communications are especially effective during
> disaster-relief operations when infrastructure is severely damaged. The
> ability to accurately determine the performance limiters of NVIS
> propagation can help in the planning of high-frequency (HF) (3-30 MHz)
> emergency communication links. In the literature, widely varying radial
> distances (from as few as 50 to up to 160 or even 320 km) for the
> coverage attainable by NVIS propagation have been reported. It is very
> difficult to plan an NVIS link for homeland security or disaster relief
> when the published guidelines vary to such a degree. In this study, a
> scientific approach was utilized to determine the NVIS performance
> limiters for varying solar conditions, times of day, and geophysical
> locations.
>
>
> ------------------------------
>
> Message: 2
> Date: Mon, 8 Jun 2020 18:14:35 -0500
> From: John Simmons <jasimmons@pinewooddata.com>
> Cc: towertalk <towertalk@contesting.com>
> Subject: Re: [TowerTalk] NVIS (not exactly towers, but HF)
> Message-ID: <3cc24071-eec0-9417-8e70-0055051b4285@pinewooddata.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> $33 for the 5 page article. I'd like to read it but I'm not sure there
> would be enough unique info to justify the price.
>
> Perusing the IEEE website I wasn't able to find the cost for individuals
> to become a member.
>
> -de John NI0K
>
> jimlux wrote on 6/8/2020 1:02 PM:
> > I guess if you have a tower, you're not so interested in NVIS <grin>
> > Interesting paper (behind IEEE paywall unfortunately) in this month's
> > Antennas and Propagation Magazine.? The authors have a series of
> > papers over the past few years of interest, looking at various
> > performance factors.
> >
> >
> > P. J. Coetzee and W. P. du Plessis, "Performance Limiters of
> > Near-Vertical-Incidence Skywave Propagation: A Scientific Approach,"
> > in IEEE Antennas and Propagation Magazine, vol. 62, no. 3, pp. 39-44,
> > June 2020, doi: 10.1109/MAP.2019.2943313.
> >
> >
> > Abstract:
> > Near-vertical-incidence skywave (NVIS) propagation is defined as
> > providing continuous coverage from nearly 0 km (just beyond the line
> > of sight) to a couple hundred kilometers from the transmitter with no
> > skip or dead zones. NVIS communications are especially effective
> > during disaster-relief operations when infrastructure is severely
> > damaged. The ability to accurately determine the performance limiters
> > of NVIS propagation can help in the planning of high-frequency (HF)
> > (3-30 MHz) emergency communication links. In the literature, widely
> > varying radial distances (from as few as 50 to up to 160 or even 320
> > km) for the coverage attainable by NVIS propagation have been
> > reported. It is very difficult to plan an NVIS link for homeland
> > security or disaster relief when the published guidelines vary to such
> > a degree. In this study, a scientific approach was utilized to
> > determine the NVIS performance limiters for varying solar conditions,
> > times of day, and geophysical locations.
> > _______________________________________________
> >
> >
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
> ------------------------------
>
> Message: 3
> Date: Mon, 8 Jun 2020 17:04:43 -0700
> From: jimlux <jimlux@earthlink.net>
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] NVIS (not exactly towers, but HF)
> Message-ID: <7014f85c-9072-7d85-94a0-b6ebc6e0d2ce@earthlink.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> On 6/8/20 4:14 PM, John Simmons wrote:
> > $33 for the 5 page article. I'd like to read it but I'm not sure there
> > would be enough unique info to justify the price.
> >
> > Perusing the IEEE website I wasn't able to find the cost for individuals
> > to become a member.
>
> Fairly pricey - $100 ish/year - although they have a deal now for half
> price (and then they'll tag you for the full amount)
>
> and then you need to get a digital library subscription (3
> downloads/month rolling over for up to 12 months) which is $20/month.
> There's a higher price option too.
>
> It's not cheap.
>
> If you're a student, it's substantially cheaper - I don't know how long
> you can be a student member, and what the qualifications are.
>
>
> If you make your living doing it, you either get the access through your
> work, or you justify it as part of "doing business".
>
>
>
> ------------------------------
>
> Message: 4
> Date: Tue, 9 Jun 2020 09:39:09 -0500
> From: Rob Atkinson <ranchorobbo@gmail.com>
> To: towertalk <towertalk@contesting.com>
> Subject: Re: [TowerTalk] NVIS (not exactly towers, but HF)
> Message-ID:
> <CALWD7Z4u+0Hhs1PyMnc7VOmCDou=xxkdGddQaEDtC5VjUwvMDw@mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> I didn't see anything in the abstract that made me want to read it as
> far as ham radio is concerned. A number of hams over the past years
> have cited military work with cloud burners as a justification for
> their usefulness in ham radio. I don't contest a horizontal antenna
> that has its highest field intensity straight up, but I do contest the
> argument for ridiculously low hanging antennas because that's what
> other services do. There are several differences between ham and
> other services that have to do with power limits, frequency
> exclusivity, transmission modes, battle conditions, and radiation
> efficiency.
>
> 73
> Rob
> K5UJ
>
>
> ------------------------------
>
> Message: 5
> Date: Tue, 9 Jun 2020 08:05:04 -0700
> From: jimlux <jimlux@earthlink.net>
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] NVIS (not exactly towers, but HF)
> Message-ID: <c562b6b1-91f7-3be8-968c-fb9358b0bc1f@earthlink.net>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> On 6/9/20 7:39 AM, Rob Atkinson wrote:
> > I didn't see anything in the abstract that made me want to read it as
> > far as ham radio is concerned. A number of hams over the past years
> > have cited military work with cloud burners as a justification for
> > their usefulness in ham radio. I don't contest a horizontal antenna
> > that has its highest field intensity straight up, but I do contest the
> > argument for ridiculously low hanging antennas because that's what
> > other services do. There are several differences between ham and
> > other services that have to do with power limits, frequency
> > exclusivity, transmission modes, battle conditions, and radiation
> > efficiency.
>
>
>
> what's interesting in the article isn't so much the NVIS stuff, but the
> modeling approach. They're doing some ionospheric ray tracing using
> ionosonde measurements. For what it's worth, the antennas they are
> using are at 0.2 wavelength, which isn't one of those knee high wires.
> At frequencies from 4-11 MHz it seems.
>
> They're using Coleman's ray tracing approach
> 21] C. J. Coleman, ?Point-to-point ionospheric ray tracing by a direct
> variational method,? Radio Sci., vol. 46, no. 5, pp. 1?7, 2011.
> Here's a report on it
> https://apps.dtic.mil/dtic/tr/fulltext/u2/a271058.pdf
>
> These days, there's a lot more real-time ionosonde data available - it's
> sort of the next step beyond NCDXF beacons or various reverse beacon
> networks.
>
>
> Of particular interest is a paper I want to track down
>
> [17] P. J. Coetzee, ?A technique to determine the electromagnetic
> properties of soil using moisture content,? South Afr. J. Sci., vol.
> 110, no. 5/6, pp. 1?4, 2014.
>
>
>
> ------------------------------
>
> Message: 6
> Date: Tue, 9 Jun 2020 11:59:01 -0400
> From: "Gene Smar" <ersmar@verizon.net>
> To: <towertalk@contesting.com>
> Subject: Re: [TowerTalk] NVIS (not exactly towers, but HF)
> Message-ID: <008901d63e76$e51bb670$af532350$@verizon.net>
> Content-Type: text/plain; charset="UTF-8"
>
> TT:
>
> Regarding ridiculously low dipoles and NVIS operation, they really do
> work after a fashion. In addition to towers, I collect military radios and
> am a member of the Military Radio Collectors' Association
> http://www.mrca.ar88.net/ . We meet on the air several times a week on HF.
> We also attend an annual gathering of the membership (predominantly east
> coast) each September in Gilbert, PA, in the Pocono Mountains. Here we
> actually use our shorter-range 51 MHz FM radios as well as our backpack HF
> rigs that the US Special Forces used in 'nam. Several of our members have
> told hair-raising stories about their use of these packs in the field.
>
> To make a potentially long story mercifully shorter, we set up my NVIS
> crossed inverted Vee antenna (75M and 60M wires) in a mountain valley 20
> miles north of our base camp at Gilbert. We operated a 50 W HF rig on 75 M
> USB and base heard us Lima Charlie. (Loud and clear.) We then disassembled
> the Vees and held the 75 M wires taut at chest height and base was still able
> to copy us; a station in upstate New York also copied us LC. The SpecOps
> guys among us told us that's how they used to deploy their skyhooks when they
> had no time to string the wires between trees.
>
>
> 73 de
> Gene Smar AD3F
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of jimlux
> Sent: Tuesday, June 09, 2020 11:05 AM
> To: towertalk@contesting.com
> Subject: Re: [TowerTalk] NVIS (not exactly towers, but HF)
>
> On 6/9/20 7:39 AM, Rob Atkinson wrote:
> > I didn't see anything in the abstract that made me want to read it as
> > far as ham radio is concerned. A number of hams over the past years
> > have cited military work with cloud burners as a justification for
> > their usefulness in ham radio. I don't contest a horizontal antenna
> > that has its highest field intensity straight up, but I do contest the
> > argument for ridiculously low hanging antennas because that's what
> > other services do. There are several differences between ham and
> > other services that have to do with power limits, frequency
> > exclusivity, transmission modes, battle conditions, and radiation
> > efficiency.
>
>
>
> what's interesting in the article isn't so much the NVIS stuff, but the
> modeling approach. They're doing some ionospheric ray tracing using ionosonde
> measurements. For what it's worth, the antennas they are using are at 0.2
> wavelength, which isn't one of those knee high wires.
> At frequencies from 4-11 MHz it seems.
>
> They're using Coleman's ray tracing approach 21] C. J. Coleman,
> ?Point-to-point ionospheric ray tracing by a direct variational method,?
> Radio Sci., vol. 46, no. 5, pp. 1?7, 2011.
> Here's a report on it
> https://apps.dtic.mil/dtic/tr/fulltext/u2/a271058.pdf
>
> These days, there's a lot more real-time ionosonde data available - it's sort
> of the next step beyond NCDXF beacons or various reverse beacon networks.
>
>
> Of particular interest is a paper I want to track down
>
> [17] P. J. Coetzee, ?A technique to determine the electromagnetic properties
> of soil using moisture content,? South Afr. J. Sci., vol.
> 110, no. 5/6, pp. 1?4, 2014.
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
> ------------------------------
>
> End of TowerTalk Digest, Vol 210, Issue 9
> *****************************************
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|