Hi everyone,
I have a question about LoRaWAN-Gateways and their Antennas.
In Europe we have a 14 dBm TX-Power restriction (correct me if i’m wrong), so when i use a Gateway with an additional Antenna, does it have 14 dBm + Antenna Gain = TX-Power?
Or isn’t it possible to exceed the 14 dBm TX-Power? Honestly I’m a little confused about that.
Thank you in advance for your help
Greetings
Your allowed to tranmit no more than 14dBm through the minimum practical antenna, a dipole or 1/4wave vertical with radial, which is 2dBi.
So if you fit a 5dBi antenna you need to reduce transmit power by 3dBm.
If you have known cable and connector losses you can increase transmitted power to compensate.
Something seems mistaken. Doesn’t TTN Europe use SF9 for RX2 and try to make up for the reduced coding gain with tons of transmit power?
RX2 is in a band with different power limits. 27dB from memory.
As far as I know, LoRaWAN duty cycles & power limits are restricted by ETSI EN300.220 standard as:
g (863.0 – 868.0 MHz): 1%
g1 (868.0 – 868.6 MHz): 1%
g2 (868.7 – 869.2 MHz): 0.1%
**g3** (869.4 – 869.65 MHz): 10%
g4 (869.7 – 870.0 MHz): 1%
With GW Downloads scheduled using the g3 sub-band allowing both higher TX Duty Cycle and also I believe slighty higher TX EIRP (+20dBm)… This allows for fact GW capacity would quickly be exhausted from DC POV if supporting lots of nodes with demanding rates of JR’s, Ack’s, Confs etc.and better reach with reduced coding gain as you say. Also Tx power out of device (not ant) can be even higher to allow for fact that GW’s will often have more remote Ants than is usual with nodes with attendant cable run and connector losses…provided actual radiated pwr is kept below the extended regulatory limit.
Extracts from an iMST App note (AN012) just pulled off the shelf-
