[HamWAN PSDR] HF radiated emissions immunity for Mikrotik gear

[Bart Kus]

Hi Levente,

Given the spacing, I suspect all that plastic-encased gear will suffer 
crashes or communication dropouts when the HF keys up.  It's also likely 
that it's producing detectable RFI in the HF spectrum with such close 
proximity.  Not sure if RFI on the RX side is important in your 
situation or not.

The first thing likely to break under TX will be your Ethernet links.  
They are long conductors which couple well to HF, and their signaling 
can be affected by HF frequencies.  At one of our sites, which is 
colocated with a medium power FM broadcast station, we had to switch to 
fiber to feed the modem with data.  The PoE is thankfully surviving the 
FM signal, so we're dual-feeding it with CAT5 for PoE and fiber for 
data.  This modem is also built inside a metal enclosure, with SFP and 
RJ45 ports available, so it was an easy fix.

In your situation, it sounds like a harder fix, given everything is in 
plastic and the sector antennas are integrated with the modems. The 
mANT30 should do a good job of rejecting HF though.  It's a waveguide 
feed with a subreflector, so there are no exposed dipole elements.  The 
waveguide will filter out any HF.  The dish modem should live in a metal 
enclosure though.  If it doesn't need to support 5 or 10MHz bandwidths, 
then Mikrotik sells 802.11ac modems that are metal enclosed and feature 
SFP ports for fiber.  If it does need to support 5 & 10MHz, there are 
these metal enclosures that can hold a Mikrotik PCB:

https://rfelements.com/products/enclosures/stationbox-alu/stationbox-s-carrier-class-2

They also have enough room to house some fiber conversion gear.  I'd 
suggest the same for the sectors, along with compatible antennas..

Or just key up and see what happens.  :)

--Bart


On 10/6/2022 10:29 AM, Levente Buzás wrote:
> Hi everyone,
>
> I am reaching out to ask for advice regarding HF radiated emissions 
> immunity for Mikrotik gear. At our HAMWan site, we have three sectors 
> (mANTBox 15s)  and two dishes (mANT30PA with BaseBox5) in the vicinity 
> (<10feet) of a multi-kW EIRP HF (10-15-20m) antenna. Since we have 
> installed the HAMWan gear, the HF gear has been offline but I am 
> worried that it will get damaged once we turn things back on. Mikrotik 
> support did not have any information on this. Does anyone have any 
> specs or practical experience to share? Any advice would be much 
> appreciated.
>
>  Thanks for your time!
>
> 73,
>
> Levente VA7QF
>
> -- 
> Levente Buzas, MASc, EIT
> Laboratory Manager
> Propagation Laboratory
> Department of Electrical and Computer Engineering
> University of Victoria
> lbuzas at uvic.ca
> +1.250.818.3937
>
> _______________________________________________
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> PSDR at hamwan.org
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