If for no other reason I would avoid the wood because it stays Wet longer even if painted
On Tue, Mar 15, 2016, 8:49 PM Christopher Gray <[email protected]> wrote: > I've been looking into the MikroTik mAnt sectors they just released, it > seems they are one of the most simple / shallow sectors that could be flush > mounted (disguised / less noticeable). Any ideas for other sectors / panels > with relatively flat front surfaces? I've discussed replacing building > components with custom pieces, and they are not interested. > > > Thanks for the help, I'll my testing and see what I can actually do within > the proposed constraints. > > > > On Tue, Mar 15, 2016 at 9:36 AM, Chuck McCown <[email protected]> wrote: > >> Try to get a minimum of 2 wavelengths away and better up to 10. Past 10 >> you will have pattern distortion but the impedance and gain will be >> unaffected. Or, get as far as you can. If under 2 wavelengths expect >> weird behavior. >> >> *From:* Christopher Gray <[email protected]> >> *Sent:* Monday, March 14, 2016 10:43 PM >> *To:* [email protected] >> *Subject:* Re: [AFMUG] Antennas Behind Wood or Glass in Old Building? >> >> Chuck, >> >> How far back should an antenna be from an obstruction (if the obstruction >> is mandatory and space is limited)? >> >> I found a nice paper with information about empirical RF loss testing >> through various materials. The main drawback is the tests are for 0.5-2 GHz >> and 3-8 GHz (skipping 2-3 GHz). Found here: >> http://fire.nist.gov/bfrlpubs/build97/art123.html >> >> Glass test results starting page 141, and wood on page 147. Based on the >> published results, it seems I might expect signal loss in the 3 dB range >> when moving from behind glass to behind 1" boards, but I'm not sure I can >> be as far back as in their testing (1 m from the horn to the specimen). >> >> -Chris >> >> On Sat, Feb 20, 2016 at 6:38 PM, Mathew Howard <[email protected]> >> wrote: >> >>> hmm... looks like bacon is the way to go, if you can't use glass or ABS >>> >>> On Sat, Feb 20, 2016 at 5:33 PM, Chuck McCown <[email protected]> wrote: >>> >>>> Well, glass, silicon dioxide is a good dielectric. And dielectric >>>> materials can make RF lenses. So if it is flat, it will not refract the >>>> signal and should faithfully transmit it with low loss. >>>> >>>> The amount of loss, assuming you are out of the reactive near field >>>> range, is related to a factor called the loss tangent or dissipation >>>> factor. It is dependent on frequency. >>>> >>>> Air =0 (depends on weather and atmospheric parameters) >>>> >>>> Glass = .02 (decreases with higher frequency) >>>> ABS plastic I use for radomes = .01 >>>> >>>> Wood = as much as .4 Commonly in the .02 range @ 3 GHz if dry. >>>> Walnut wood = 1.4 @ 10 MHz >>>> Water = .157 >>>> >>>> Bacon (smoked) = .05 >>>> >>>> >>>> >>>> *From:* Christopher Gray <[email protected]> >>>> *Sent:* Saturday, February 20, 2016 4:00 PM >>>> *To:* [email protected] >>>> *Subject:* Re: [AFMUG] Antennas Behind Wood or Glass in Old Building? >>>> >>>> The building is 200+ years old, so most of the glass is old enough. >>>> I've requested to replace some panes with acrylic sheets, but I don't think >>>> they will let me. >>>> >>>> Thanks for the feedback. It sounds like mounting behind glass is much >>>> preferred over wood. I have not found good loss estimates yet, but I >>>> haven't dug into it too far. >>>> >>>> >>>> On Sat, Feb 20, 2016 at 4:59 PM, Eric Kuhnke <[email protected]> >>>> wrote: >>>> >>>>> Old windows are not so bad RF transparency wise. It's even possible to >>>>> use 80 GHz through glass in high rise office buildings that predate 1982 >>>>> or >>>>> so, when metallic coatings and special IR/UV coatings on windows started >>>>> to >>>>> become possible. >>>>> >>>>> It's the *new* windows you have to worry about. >>>>> >>>>> >>>>> >>>>> On Fri, Feb 19, 2016 at 7:37 PM, Christopher Gray < >>>>> [email protected]> wrote: >>>>> >>>>>> I may have an opportunity to install some radios inside a steeple >>>>>> with some very specific requirements. I'm currently considering 5 GHz and >>>>>> 3.65 GHz radios for this location. I'd like to do some PTP and PMP links, >>>>>> but I cannot afford to lose too much. >>>>>> >>>>>> I have the option between mounting behind 1" thick solid boards, 2x >>>>>> 1" thick solid boards, or behind original windows. Are locations with >>>>>> such >>>>>> barriers even worth entertaining? If so, would it be best to ask for >>>>>> locations behind wood or glass? >>>>>> >>>>>> Thanks you, Chris >>>>>> >>>>>> >>>>> >>>>> >>>> >>>> >>> >>> >> >> > >
