RE: Long Range SUB 1 GHz RF Modules

ilyasha — Thu, 06 Dec 2018 17:01:48 GMT

what is the value of the wavelength? how do we measure it? is it constant?

RE: Long Range SUB 1 GHz RF Modules

Øyvind Karlsen — Fri, 08 May 2015 12:01:46 GMT

Hi Ravinder Reddy,

The nRF905 has four different transmit powers: -10dBm, -2dBm, 6dBm and 10 dBm(current draws are respectively: 9mA, 14mA, 20mA and 30mA, supply voltage 3.3V) , as well as a typical sensitivity of -100 dBm. It can operate on three different frequencies: 433/868/915 MHz. To find the theoretical maximum range, R, for the radio system, we can use Friis equation. First we make some assumptions: over-the-air LOS loss of 50 dB. Good reciever and sender antennas with 0 dBi gain. Calculations are shown in the picture below:

These results are in line with what you might expect for an outdoor application with direct line of sight, and no meteorological phenomenon. If you were to use the product in a non line of sight application, the modelled loss should be increased by 30-50 dB depending on the materials the signal has to pass through. As you can see range depends heavily on several factors. Longer range could be achieved by using dipole, or higher gain antennas, which would drastically increase the range.

For more information see the product specification.

Best regards, Øyvind