[OZAPRS] Mine's bigger than yours (?)

vk2tv vk2tv at exemail.com.au
Thu Aug 3 08:52:36 AEST 2017

On 02/08/17 19:33, Liz wrote:
> We get attenuation from wine tanks to the north, about 10m away.
> Currently the antenna is about 5m above the roof which is 4m above the
> ground. The ground is flat for an extended distance. In those
> directions with no interference / attenuation I can receive from almost
> 350km away, with the plane at 11000+ metres.
> The plan is to raise the antenna further, but the coax won't stretch
> any further.
> -+-+-+-+-+-+-+-+-+-+-+
> Liz

I used to get serious attenuation from wine bottles, and then I stopped 

Raising the antenna's height might not produce a significant difference 
in range, it all depends on how close any obstacles are to YOUR end of 
the radio path. The closer to your end any obstacles are, the greater 
the height increase you'll need. As per an example for here where my 
outlook to the east is pretty much unobstructed for most directions, I 
only stand to gain another 19km (in 460km) by increasing antenna height 
from 1m to 30m, for an aircraft at about 38,000ft. However, to the west 
where I look into the crest of a hill just 50ft away, a 15m mast would 
make one heck of a difference.

A useful test is to run a path profile program such as SPLAT! in Line Of 
Site (LOS) mode to reveal just what gets in the way for various antenna 

Here's a useful radar horizon calculator ... 

Ray vk2tv

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