RAK Glass Fiber Antenna with 6dBi peak gain


Because I seem only to reach 250 meters from my gateway, I want to upgrade the antenna on my gateway.

I am going to connect a RAK Glass Fiber Antenna with 6dBi peak gain, N-Type iPEX Connector, support 868MHz to my RAK2245 board.

If I understand correctly because I have a +dBi + gain I must configure the RAK gateway to have lower transmission power.

Anyone can tell me what to modify in the RAK gateway config?

Is there also a good way to verify if the transmitted power is not exceeding the legal limit easily?

Personally if I was only getting 250m range from a gw (yes it has happened!) I would investigate why and what affecting - equipment or environmental issues - before looking to invest in better antenna.

Can you take the GW elsewhere to run checks to eliminated built environment issues?..Check existing ant & kit correctly set up with tight connections using correct connectors (e.g. sma m/f, sma-rp m/f etc.). Check test node with other TTN gw’s etc.

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I live in an apartment second floor in a small village.

By I also heard how bad antenna’s get shipped with products so I want to get one official one from RAK first.

250m are so few that likely the antenna is not the only issue. One crucial thing is where the gateway is placed: if you put it in the middle of the apartment, table level, even with the new antenna you will not reach kilometers. Plus, checking connections is also a must.

This one is at my window,

But I am starting to wonder if this antenna is actually good:

Seems tiny for something that can communicate long distance.

I think I can answer my own question

In the global_conf.json file

  "SX1301_conf": {
        "lorawan_public": true,
        "clksrc": 1,
        "antenna_gain": 0,

I probably have to set this to 6dBi peak gain for this newer antenna

  "SX1301_conf": {
        "lorawan_public": true,
        "clksrc": 1,
        "antenna_gain": 6,  <<<-------------------

That depends on which packet forwarder you are running, some older code bases do not handle the setting correctly resulting in no transmissions.

I’d leave that alone for several reasons:

  • +6dBi (rounded up for marketing) is +5.1 … 5.8dBi (technical)
  • +5.1 … 5.8dBi (still marketing) is +2.95 … +3.65dBd gain (best guess) in real
  • you have cable and connector losses of the 1m RAK antenna cable of ~ -0.9dB
  • so in theory you have +2.05 … +2.85dBd gain for spare which is easily dampened by your 2nd story appartment’s walls.
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You probably do, if you want to stay legal, which is good.

I am not aware of any excemptions for what might possibly be absorbed by objects some distance from the actual antenna.

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So “legal” is what the transmitter emits, now what gets out beyond the wall/window.

Makes sense since this is a very easy rule to validate.

I didn’t talk about exemptions. I referred to his bad reception capability which will not improve that much with an +6dBi antenna. “Big gain”-antennas for LoRa (with it’s huge link budget) are overestimated. :blush:

Legal depends on the output of the antenna, not the output of the transmitter. So if you suffer a huge loss in the cables and connectors a 6dBi antenna might well be legal without changing the transmitter output.

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mmm. Looking at the antenna, likely you need something better.

Two days before I was able to establish a LoRaWAN link of 8.7km LOS in urban area with a tiny antenna similar to THIS on a ~ +16dBm transmitting INDOOR node. The signal was received with an astonishing -137dBm. The relevant receiving gateway uses an λ/4-Ground Plane outdoor antenna. Most important for an antenna is it’s exact frequency band tuning.

edit reason: typos

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