Range with TTN Gateway and antenna indoors?

(Mark D) #1

I bought a TTN gateway about a month ago, and have tested it with a few nodes. One is an Adafruit Feather Lora M0 and the other is a TTGO T-beam. I had the tx power set to 20 dBm in both cases. The gateway is in my attic, near a window and about 9m off the ground. I can’t get more than 0.5km range with this setup. Would you expect a greater range or is this typical? Before I spend money and time to install an outdoor antenna, I want to know that there isn’t a problem with the gateway.



(Jeff Uk) #2

Take outside temporarily - pref into area where you can get good line of site to distant points - e.g. hillside and try again there - if still poor then may be a problem but likely its down to materials surrounding you when in attic - have found several times that various types of roofing mineral felt have high metallic content causing screening or if roof space insulated then the insulation material can have foil backing or be a foil sandwich again causing problems, as can plumbing, metal water tanks, roof infrastructure girders, etc. in loft space. I’ve occasionally found mounting high in attic space a problem but then trying down at floor level worked much better as signal was able to escape through the eves of the roof line :wink: Windows themselves especially more modern double/triple glazed units can often be made with architectural glass or low-K (thermally insulating) glass which is made with thin metal/metal oxide coating that can be quite effective at cutting RF…you may find <Ghz cellular signals also weak up there which gives a clue despite height c/w rest of the building…

If the window opens, again as a temp measure try pushing ant outside with a short RF feeder - 1-3m RG58 ok - you will loose some signal but being high/outside should more than compensate…perhaps holding ant aloft taped to top of 1-2m 15/22mm poly pipe to keep upright in air.

(LoRaTracker) #3

Who can know, it depends on the construction of your attic. For instance if the walls in the attic have foil lined plasterboard, who knows how far the signals might go.

The only way to eliminate the guesswork, is as suggested, locate it out doors on temporary basis.

Its very unlikely that an outdoor mounted antenna will make things worse, so why not do it anyway.

I have a (temporary) gateway in my attic with no external antanna, its does not get very far either, as expected really.

(Ud Lo Ra) #4

It also depends on the environment: urban, rural, …? Urban may give extra difficulties.The node antenna is also crucial.
I had a single channel gateway in similar situation (under the roof, about 8m off ground, homemade GPA antenna), in semi-rural area, and I reached slightly over 6km, but with a 20cm antenna on the node.

(Mark D) #5

Thanks to everyone who responded so far. It’s an urban area - I live in downtown Toronto but there are almost no tall buildings in the way. If you would like to see the results I have seen so far, you can look for my tests at ttnmapper.org, they all have a name starting with “mapMyDrive_xxx” such as this one : https://ttnmapper.org/experiments/map.php?name=mapMyDrive_v0011.t-beam

The tests with the adafruit board all used a 80 mm wire antenna, and the rance was very similar to that of the t-beam.

The antenna is almost against a north facing window in the attic, and it’s a single pane of ordinary glass - easily at least 60 years old.

There is no metal in the roof, it’s a wooden frame with shingles. I was expecting that all propagation would be through that window. It’s not easy to just move the gateway outside at the moment, it’s winter here. I was mainly trying to get an idea of 0.5 km is reasonable as it seems on the low side. I know there are many factors involved but was hoping for closer to 1 km if the node was north of my home.

(Jeff Uk) #6

Firstly - winter…is there ice/snow cover on roof?
Second - North facing window? Not looked at your mapping but is range consistent all around building or limited/better in sight of the window? If age is right and this is early Pilkington float glass I believe in early days as they refined process more tin ions would embed into the bed side of the glass - potentially reducing RF propagation. (You can see effect of the metal ions if you look into edge of a sheet of glass and apply a UV source to the flat surface - one side - the bed side -will fluoresce more than the other! :wink:
3rd A neighbour here in UK has (Canadian - some type of cedar? - as it happens) shingles on sloping cladding to their upper story and attic space…for rain water ingress/run-off protection it is on top of batoning on top of a high metallic content roof felt, with the inside then insulated with Cellotex - a local brand of thick foam insulation, that unfortunately has heat reflecting foil layer before then a dry wall insulation - again foil backed :frowning: and finally skimmed with plaster/hard-wall…their attic space and bedrooms are veritabile Faraday cages with poor LoRa transparency and poor cell phone coverage upstairs!..just saying… :wink:

Get the ant outside per earlier and see how you get on :slight_smile:
FYI a TTN GW in my home office roof space (though tiled roof with low metal roof felt and little insulation!) is getting 4.5 - 7km range depending on direction and terrain…