Direct mount antenna bad idea?

descartes
Sat, 31 Jan 2026 18:41:17 +0000

I’ve spent the last 6 months mapping out the breadth & depth of antenna design, propagation and deployment, I’d consider it to be a 10,000 hours endeavour and the rest. Everything is a compromise. Modelling works until it doesn’t.

As AI is fed the body of knowledge called web pages and anyone can publish, which they do, and because it is a dark art and radio amateurs like to dabble, the aggregate nonsense is going to dilute the actual facts quite considerably, so anything AI has to offer can only provoke some thought. Or despair.

At least AI did note that the ground plane of the heavy metal box may be messing with the McGill antenna, what we don’t know is if the RAK antenna is tuned for being on the box.

I have a number of RAK 434 & 868 antennas and none of them have a ground plane at the top of the 6m Aluminium mast I use. They are connected via WestFlex WF-103 (close in spec to LMR400 but 1/3rd the price but still expensive). They seem to work just fine. But if I’ve got a null spot, I’d install a supplementary gateway.

More general comments:

The first thing for antennas is that every situation is unique.

The shape of the terrain and soil composition figure up the top of the list for even the most basic of antenna setups. If you are in a wooded area, the type of trees, how wet the leaves are, both internally & externally, how close together they are will also be a major factor.

So all you can do is test using a tool, he says ironically, like TTN Mapper.

The second thing to consider is that RAK’s kit is well regarded, the antennas they bundle are not a PoS ( ) but for sure, have to fit a balance between construction, efficacy and durability, so probably not the absolute best.

And then there are the frequencies in use: 902.3 to 914.9 MHz for the 64 channels and 923.3 to 927.5 MHz for downlinks. So the antenna HAS to be OK across that range. The 915 bit is middle ground and as such is a huge red herring ( ), aka over simplification, aka misleading aka shorthand for the ISM band of 902–928 MHz.

I can’t see the particular antenna from McGill, but they may be able to help you out with the right specific product. Given some of the data sheets don’t have the polar diagrams on, I’m not sure what to note. However, if you can afford some decent connectors plus a length of LMR400, it’s worth a try if the deployment is worth it.

Remember, you need to set the gateway for the dBi of the antenna so you don’t exceed local legal limits. Sometimes a big honking antenna is standing still or going backwards.

@Jeff-UK will go in to the details, but woods & UHF aren’t a great mix, other discussions over the years on how to do LW in woods (if a device transmits in the woods but no gateway hears, does it actually use any power?) are available by searching (top right).

TL;DR: Do some mapping then install more gateways.