[MLB-WIRELESS] New Lightpointe product

mw at freenet.net.au mw at freenet.net.au
Wed Aug 5 19:41:09 AEST 2015

Yeah, bugger – that’ll kill it! :-D


I looked at the detail, and there’s actually a peak for oxygen absorbtion smack on 60GHz – that’s why they open that band up for class license no doubt ;)


It looks like it is ‘only’ about 11dB though, but that’s still easily enough to put a dampner on that idea ;)


(good article about all that here: https://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet70/oet70a.pdf)


Nonetheless, It’s still an interesting alternative to 24GHz :)





From: Tony Langdon [mailto:vk3jed at vkradio.com] 
Sent: Wednesday, 5 August 2015 7:25 PM
To: mw at freenet.net.au
Cc: melbwireless-bounces at lists.wireless.org.au
Subject: Re: [MLB-WIRELESS] New Lightpointe product


On 5/08/2015 7:18 PM, mw at freenet.net.au <mailto:mw at freenet.net.au>  wrote:

Hey Tony,


I thought so too until I took a look at the LIPD docs:


Data communications transmitters used outdoors


150 W

1.  Transmitters are limited to land and maritime deployments.

2.  Maximum transmitter power must be 20 mW or less.

3.  Spurious emissions outside the band must be less than ‑30dBm/MHz.

4.  For outdoor use only.

According to this detail, max EIRP is 52dBm which means that 8 dBm max tx capability with 47dBi antenna still comes in under the regulatory limits.

According to free space attenuation calculator (here http://www.radio-electronics.com/info/propagation/path-loss/free-space-formula-equation.php) 60GHz over 10km is only 146dB, so if that lightpointe gear can run at full 55dBm EIRP, then result at the receiver (assume 47dBi antenna) will be up to around -47 which will surely be sufficient for a decent link :)

Tell you what, though, 0.6 degree antenna beam will make it damn tricky to align, and to KEEP aligned when there is a lot of heat fluctuation in the air ;)

But even with the 44dBi antenna, it only adds 18dB to the calculations, and -65 over 10km is still pretty good….

Did you include the additional 16dB/km of Oxygen absorption loss?  That's on top of normal 1/R^2 free space losses.  So, there's 160dB of absorption loss from oxygen in the atmosphere over a 10k path.  Hmm, 300dB path loss, that's worse than VHF moonbounce (~270dB)! :)  

73 de Tony VK3JED/VK3IRL
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.wireless.org.au/pipermail/melbwireless/attachments/20150805/7d2f0fff/attachment.html>

More information about the Melbwireless mailing list