[NLRS] Dayton VHF/UHF/uwave forum

[Baker, Donn B]

Hi Brent,
Didn't realize you were there!  Sorry I missed you.

Re: trees, etc., I have seen the effect begin as low as 432 MHz even if the leaves are dry (i.e., not rain-soaked).  It can affect 2m if the foliage is dense and wet.

A formula for estimating "foliage loss:"
L(dB) = 0.2 * f^0.3 * R^0.6
 where f = MHz
       R = depth of foliage in meters

valid for: 
  200 <f< 95,000 (marginal for 2m)
  R <= 400 m

>From CCIR Rpt 236-2
FCC OET Bulletin 70

This is for "dry" foliage, not rain-coated.

At 200MHz, the loss from a single, large tree (10m) is about 4 dB !  At 432, its about 5dB !!

73 Donn
WA2VOI/0



> -----Original Message-----
> From: Brent Casavant [mailto:b.j.casavant at ieee.org]
> Sent: Tuesday, May 18, 2004 9:03 AM
> To: Northern Lights Radio Society
> Subject: [NLRS] Dayton VHF/UHF/uwave forum
> 
> 
> Hello all,
> 
> I'm wondering if any of you were at the Dayton 
> VHF/UHF/microwave forum.
> If so, I have a question, and an observation.
> 
> First, during the K8GP presentation by Owen Wormser, he mentioned that
> they once were going to operate a VHF contest from a site where their
> towers couldn't clear the surrounding trees, but due to that 
> decided to
> scrap the whole thing and went back home.  On Sunday as I 
> thought about
> that statement and its impact on my contesting methods, I wondered if
> this was only due to the impact on microwave operations.  Or could it
> be that this presents a problem for VHF/UHF bands as well?  With which
> bands do I have to start worrying about this?
> 
> Second, the presentation on getting started on 10GHz by W2RG and K9AYA
> was somewhat interesting, though a lot less technical than I 
> anticipated.
> What crossed my mind, however, was that these guys may well 
> be interested
> in participating in the Lake Superior trips/experiments -- they seemed
> quite excited about experiments in microwave propagation.  From Aurora
> I seem to remember that there's some desire to encircle the lake with
> operators, and really try the long haul across the lake.  
> Anyway, since
> they're already on that side of the lake (relatively 
> speaking), someone
> may want to invite them to drive up to the south or east shore.
> 
> Brent
> 
> -- 
> Brent Casavant			http://www.angeltread.org/
> KD5EMB				-.- -.. ..... . -- -...
> 44 54'24"N 93 03'21"W 907FASL	EN34lv
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