MIke/WiSPA readers - Here two studies in the public domain published by the US NTIA and study from the Univ. of Texas.(It would be handy to put a table together for WiSP operators just like the ohm resistance tables are done for electrical contractors).
¡§Radio Propagation Considerations...¡¨ .. the results of these studies indicate that for the first 30 m of foliage depth, the increase in vegetation loss is nearly linear at a rate of 1.3-2.0 dB/m, depending on frequency; beyond 30 m, the curve decreases at a rate that averages only 0.05 dB loss per meter. Propagation through the deciduous orchard (in the foliated state) resulted in less loss than propagation through the conifer orchard for any given combination of frequency, transmitter height, and foliage depth. http://www.its.bldrdoc.gov/pub/ntia-rpt/96-331/report_96-331.pdf and; "Attenuation from Trees and Forests Trees can be a significant source of path loss, and there are a number of variables involved, such as the specific type of tree, whether it is wet or dry, and in the case of deciduous trees, whether the leaves are present or not. Isolated trees are not usually a major problem, but a dense forest is another story. The attenuation depends on the distance the signal must penetrate through the forest, and it increases with frequency. According to a CCIR report [10], the attenuation is of the order of 0.05 dB/m at 200 MHz, 0.1 dB/m at 500 MHz, 0.2 dB/m at 1 GHz, 0.3 dB/m at 2 GHz and 0.4 dB/m at 3 GHz. http://www.utexas.edu/research/mopro/papercopy/chapter02.pdf F.Lopez Wirelss practitioner (and learning all the time) --- Mike Hammett <[EMAIL PROTECTED]> wrote: > Kinds? um... I know coniferous vs. deciduous and > a couple different > kinds of deciduous, but that's about it... Maple, > crab apple, locust, > that's about it. > > > ----- > Mike Hammett > Intelligent Computing Solutions > http://www.ics-il.com > > > ----- Original Message ----- > From: "CHUCK PROFITO" <[EMAIL PROTECTED]> > To: "'WISPA General List'" <wireless@wispa.org> > Sent: Friday, June 22, 2007 12:13 PM > Subject: RE: [WISPA] 5 GHz attenuation > > > No one talks of the type of trees. We've noticed > getting through a line of > poplars, adjust antenna size, not much of a problem. > But one pine tree, or > a well placed ash, near impossible. Maybe the pine > needles attenuate more > because they are thin and in all directions thus > absorbing all reflections > ?? Anybody else see this. > > Chuck Profito > 209-988-7388 > CV-ACCESS, INC > [EMAIL PROTECTED] > Providing High Speed Broadband > to Rural Central California > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On > Behalf Of Mike Hammett > Sent: Friday, June 22, 2007 9:57 AM > To: WISPA General List > Subject: Re: [WISPA] 5 GHz attenuation > > > Could you provide some sort of numbers? How much > loss does that 1/4 mile of > > water-retaining trees have? > > The town is basically a square with the tower on the > far west side in about > the center. It is 1/2 mile to the extreme corners, > so there are a lot of > people 1/4 mile and less. > > Someone on another list mentioned water retention as > a show-stopper, but my > limited experience had me thinking just about > anything less than a 1/2 mile > would work. > > > ----- > Mike Hammett > Intelligent Computing Solutions > http://www.ics-il.com > > > ----- Original Message ----- > From: "Graham McIntire" <[EMAIL PROTECTED]> > To: "WISPA General List" <wireless@wispa.org> > Sent: Friday, June 22, 2007 11:25 AM > Subject: Re: [WISPA] 5 GHz attenuation > > > >I have two towers running MT APs at 5.8 with CM9s > and 16 dBi horiz > > sectors. Using Osbridge 5GXi's as the CPE, I have > clients a few miles > > out with non-LOS and the occasional treeline > without any issues. > > > > I also have one house about 3/4 mile away from my > tower that's going > > through nearly 1/4 mile of scattered trees. It > attenuates pretty > > badly during heavy rain until the leaves on the > trees dry out, but > > stays connected. It's my parents-in-law's house, > so they're a little > > more forgiving if it happens to drop than a client > would be ;) > > > > Half a mile with scattered trees shouldn't be a > problem for you, even > > with snow/rain attenuation. > > > > Graham McIntire > > Verona Networks > > > > > > On 6/22/07, Mike Hammett > <[EMAIL PROTECTED]> wrote: > >> I have a 5 mile link where I'm not quite sure if > the antenna is above the > >> trees or not as it is on top of a mast. That > link is on the better side > >> of -80 for almost 2 years. Based on that I'd > think I'd be okay at a half > >> mile or less. I figured that with most of the > town at better than -60 > >> and a > >> lot better than -50, I could stand to go through > a few meters of tree, > >> but > >> that's why I came here to ask. ;-) > >> > >> Based on the numbers on the site I looked at, 10 > db of attenuation is 27' > > >> of > >> foliage. That'd put 20 db at 55' of foliage. > >> > >> > >> ----- > >> Mike Hammett > >> Intelligent Computing Solutions > >> http://www.ics-il.com > >> > >> > >> ----- Original Message ----- > >> From: "Jack Unger" <[EMAIL PROTECTED]> > >> To: "WISPA General List" <wireless@wispa.org> > >> Sent: Friday, June 22, 2007 10:22 AM > >> Subject: Re: [WISPA] 5 GHz attenuation > >> > >> > >> > Mike, > >> > > >> > Good to go as long as the TV towers allow you > to get the CPE antennas > >> > above the trees. > >> > > >> > jack > >> > > >> > > >> > Mike Hammett wrote: > >> >> Most of my coverage area is open fields, so > there isn't much to making > > >> >> a > >> >> link work. > >> >> > >> >> I have an increasing demand to install an AP > in a small town (no point > >> >> within town is further than 1/2 mile away from > the tower site). I > >> >> prefer > >> >> to use 5 GHz due to the amount of spectrum > available. An article I > >> >> read > >> >> said 1.5 db per meter of foliage or 20 db per > tree in 5 GHz. > >> >> > >> >> The grain leg is 100 - 150 feet tall. Many > houses have TV towers. > >> >> Radio > >> >> Mobile (not counting foliage) says the worst > signal I can expect to > >> >> see > >> >> is in the 60s with most in the 50s or 40s. > >> >> > >> >> Safe to assume that most of the town will be > good to go? > >> >> > >> >> > >> >> ----- > >> >> Mike Hammett > >> >> Intelligent Computing Solutions > >> >> http://www.ics-il.com > >> >> > >> >> > >> > > >> > -- > >> > Jack Unger ([EMAIL PROTECTED]) - President, > Ask-Wi.Com, Inc. > >> > FCC License # PG-12-25133 > >> > Serving the Broadband Wireless Industry Since > 1993 > >> > Author of the WISP Handbook - "Deploying > License-Free Wireless WANs" > >> > True Vendor-Neutral Wireless > Consulting-Training-Troubleshooting > >> > FCC Part 15 Certification for Manufacturers and > Service Providers > >> > Phone (VoIP Over Broadband Wireless) > 818-227-4220 www.ask-wi.com > >> > > === message truncated === ____________________________________________________________________________________ Looking for a deal? 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