RAK Glass Fiber Antenna with 6dBi peak gain

Gateways RAK Gateways
1

Hello,

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?

2

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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3

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.

4

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.

5

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.

6

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,  <<<-------------------
7

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

8

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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9

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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10

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.

11

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:

12

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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13

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

14

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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