9 Sep
2021
9 Sep
'21
10:58 a.m.
The issue with such long SHF links (especially over water) is "tropospheric
ducting".
You need to calculate the antenna height based on line-of-sight and have antennas
at that height, but you also need extra link antennas at much lower height because
tropospheric ducting may curve the signals along the water surface and they can be
received in the inversion layer close to the ground, but not at the height you need
for a line-of-sight path.
SHF DX-ers are very familiar with this phenomenon, where it is possible to make a QSO
from the beach or from a coast house at 30m elevation, but not from a mountain
400m high.
With two different link setups you may be able to get coverage for a larger percentage of
time.
Rob
On 9/9/21 5:52 PM, Chaplain Dave Sparks via 44Net wrote:
The problem, as I see it, would not only be signal
strength, but also
overcoming the curvature of the earth with suitably high antennae on both
ends