It is known that the tempting features of free space Non-Line-Of-Sight
(NLOS) communications systems operating in the Ultraviolet C-band
between 200 and 280 nm are the significantly reduced solar irradiance on
ground level, the intense scattering and its combination with strong
absorption which ensures the covertness against distant eavesdroppers or
jammers. In the majority of the experimental surveys that have been
published so far, the performance of point-to-point links has been
evaluated under clear atmosphere without taking into account the weather
conditions. In this work, it is shown that harsh atmospheric conditions
due to fog appearance can be advantageous to short distance NLOS
transmissions at 265 nm. Initially, the impact of fog on the losses of
the diffuse wireless channels was investigated theoretically.
Afterwards, an experimental survey of both the losses and the
performance of low rate amplitude signals' transmissions for two
atmosphere cases followed. Initially, the satisfactory relation between
scattering and absorption at 265 nm was verified by deploying outdoor
NLOS point-to-point links under clear atmosphere. The transmitter
consisted of 4 Light Emitting Diodes and the optical part of the
receiver included a filter and a Photo-Multiplier tube. Then, the
beneficial impact of artificially generated fog on scattering was
exploited not only to enhance the system performance but also to
identify the modification of the conditions. The experimental results
showed a clear decrease of both the losses and the Bit Error Rate under
fog conditions making such a system a perfect candidate for low rate
communications under dense atmosphere
