At 07:57 AM 11/8/2005, Marlon K. Schafer (509) 982-2181 wrote:
>Anyone know where we can get our hands on that research?
Which research in particular?
The older stuff tends to be published in places like IEEE Transactions on
Antennas and Propagation, and sometimes in Radio Science. Newer things,
particularly when it's in connection with radar remote sensing, is often
published in Journal of Geophysical Research (usually abbreviated JGR), as
well as the Trans. on Ant. & Prop.
There's also an enormous amount of stuff that's published (after a fashion)
on one form or another of "technical reports". These can be pretty hard to
track down, particularly if the author is dead or otherwise incommunicado.
There's also some handbooks online at JPL:
http://descanso.jpl.nasa.gov/Propagation/propagation.cfm
but they tend to be oriented more towards links where one end is a
satellite, so propagation through lots of trees or hills isn't usually an
issue.
Typically, one finds one paper that's interesting, and then you look for
other papers by the same author, or look for the papers referenced by the
paper. Google, IEEE Xplore, and WebOfScience are your friends.
Some authors and years they published (I'll see about conjuring up a better
bibliography on this) mostly oriented towards HF and VHF
Austin (98,00,02,03) (HF NVIS)
Burke (84, 89) (NEC related stuff)
Breakall (94) (using NEC-BSC for terrain modeling)
Cavalcante (82,83,94,98) (propagation in forests)
Coleman (02) (lightning noise propagation)
Hagn (88,99) (ground parameter measurement, propagation
through trees)
Wallace (92) (HF in Desert Storm)
Lindenmeier (88) (active antennas)
Lastovicka (?) (antenna designs for ionospheric effects)
Tamir (67, 77) (trees and terrain)
Vogel (99,etc) (trees)
You might also look at the ITS site at NTIA, where they have lots of
references to the Longley-Rice modeling.
>thanks,
>Marlon
>(509) 982-2181 Equipment sales
>(408) 907-6910 (Vonage) Consulting services
>42846865 (icq) And I run my own wisp!
>64.146.146.12 (net meeting)
>www.odessaoffice.com/wireless
>www.odessaoffice.com/marlon/cam
>
>
>
>----- Original Message -----
>From: "Jim Lux" <jimlux@earthlink.net>
>To: "Frederick M. Mott" <ab8ah@earthlink.net>; "'Jim Brown'"
><jim@audiosystemsgroup.com>
>Cc: <towertalk@contesting.com>
>Sent: Monday, November 07, 2005 4:49 PM
>Subject: Re: [TowerTalk] Tree attenuation
>
>
> > At 04:20 PM 11/7/2005, Frederick M. Mott wrote:
> >>I operated a MARS station (AB8AH - 1st Bde 1st Inf Div) in Phouc Vinh than
> >>in Quan Loi, Viet Nam during 1967 and 1968. There were no trees at both
> >>locations near our towers (100 ft Rohn 25G and a 70 ft commercial tower)
> >>except for 1 palm tree (about 20 ft and 1 10 ft banana tree). Our site
> >>worked very well, we ran approximately 1,100 to 1,200 phone patches a
> >>month.
> >>A sister station, AB8AAB, 2nd Bde of the 1st Inf Div was located in a
> >>rubber
> >>plantation (jungle environment)at Lai Khe. Their wire beam was suspended
> >>from the rubber trees. They were lucky to run 50 phone patches a month.
> >
> > It is precisely the sort of thing you observed 40 years ago that prompted
> > the research of George Hagn at SRI (and others, like Tamir) on propagation
> > through or around forests and jungles. They went out and did a bunch of
> > testing, first in Eucalyptus forests around Palo Alto, CA, then in forests
> > in Australia, and finally in actual jungle. This test campaign also
> > prompted the development of the Open Wire Line technique for measuring
> > ground dielectric properties because their measurements that used the
> > measured feedpoint impedance of (low) dipoles were suspect. SRI also
> > developed the RELEDOP technique to measure 3D far field patterns of HF and
> > VHF antennas.
> >
> > There was some research after that, but really, all the work and analysis
> > was done back then, and not much has changed since then, there being no
> > commercial need anymore. These days, HF propagation research foucuses
> > more
> > on Over The Horizon radars, typically for observation of ocean surfaces,
> > and they manage to put their antennas in places without trees or forests.
> > (and a bit of work on spectral monitoring in an OTH sense, to look for
> > "bad
> > guys" talking on their HF radios)
> >
> > Given that lots of tactical radios work in the 30-88 VHF band, and the US
> > military emphasis on being able to fight a land war in Europe, there was a
> > moderate amount of research on propagation at those frequencies in
> > temperate forests, which manifests itself in the papers from the late 70s
> > and early 80s.
> >
> > There's also a huge amount of work in the 800 MHz area in that time
> > period,
> > supporting cellular telephone applications. Lots of guys driving around
> > in
> > monitoring vans making precision field strength and multipath measurments
> >
> > The research these days is all on various microwave frequencies (think in
> > terms of cellular, PCS, and WLAN applications), and more often than not,
> > for urban environments. There's also a fair amount of research on this
> > (particularly about 10 years ago) to support various satellite to mobile
> > applications (like Sirius and XM <grin>) which oddly, the customers expect
> > to work when they're driving through the forest as well as through the
> > city.
> >
> > It's all about money, after all... If you want to do research, you've got
> > to do something that will let you eat and pay the rent (there's only a
> > limited amount of truly philanthropic money out there) and that means
> > having someone with cash interested in the data. McArthur grant screeners
> > may contact me at my email address. I'll be happy to take this on for a
> > few
> > years, and half a million dollars would probably be enough to do a decent
> > measurement and analysis campaign.
> >
> > I suspect that if we were ever to be involved in a significant ground war
> > in a forested environment, folks would start paying attention to HF and
> > VHF
> > propagation in forests again. For now, though, the existing solutions
> > (manpack and vehicular HF and VHF radios with ALE) work "well enough".
> > You
> > too can own the current state of the art for about $20-25K.
> >
> >
> >>-----Original Message-----
> >>From: towertalk-bounces@contesting.com
> >>[mailto:towertalk-bounces@contesting.com] On Behalf Of Jim Lux
> >>Sent: Monday, November 07, 2005 5:13 PM
> >>To: Jim Brown
> >>Cc: towertalk@contesting.com
> >
> >
> > _______________________________________________
> >
> > See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> > Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
> > any questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
>
>_______________________________________________
>
>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
>Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
>any questions and ask for Sherman, W2FLA.
>
>_______________________________________________
>TowerTalk mailing list
>TowerTalk@contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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