If you are using 2.4 GHz, how are you remaining in the near field yet extending the distances out to many km?
At 2.4GHz, λ is approximately 0.125m. Since the wavelength is small, the antenna is likely to be "electromagnetically long", i.e. the size of the antenna is of comparable size to the wavelength.
The edge of the near field in this case is defined by the Fraunhofer Distance [0][1]. Let's assume we want the edge of the near field to be 1km away. Running that through the Fraunhofer distance equation to compute the largest dimension of the radiator, we get ~7.9m. That's huge. For 10km it is 25m.
At 2.4GHz, λ is approximately 0.125m. Since the wavelength is small, the antenna is likely to be "electromagnetically long", i.e. the size of the antenna is of comparable size to the wavelength.
The edge of the near field in this case is defined by the Fraunhofer Distance [0][1]. Let's assume we want the edge of the near field to be 1km away. Running that through the Fraunhofer distance equation to compute the largest dimension of the radiator, we get ~7.9m. That's huge. For 10km it is 25m.
0. https://en.wikipedia.org/wiki/Near_and_far_field#Electromagn...
1. https://en.wikipedia.org/wiki/Fraunhofer_distance