Hello Mal,
At 17:36 1/10/01 +0100, you wrote:
Unfortunately there is no perfect ground and no lossless loading coil so in
practice (on 136kHz) a longer antenna will outperform a shorter and the one
What I have been saying all the time and I am glad you and others realize
this
at LAST!!!!
I (and probably all the others) have been understanding this all the time.
It doesn't change anything on the fact that a lower antenna efficiency can
be perfectly compensated by higher power.
Remember that we are ERP limited (1 Watt).
So if a 'big guy' has 40m high vertical with a lot of toploading (radiation
resistance something like 0.5 Ohm) he will have to limit the antennacurrent
to about 1.5 A in order not to exceed the 1W ERP limit (assuming 50 Ohm
loss this means running only +/- 100 Watt).
On the other hand can a 'little boy' who is damned to use a 10m wet string
as antenna (radiation resistance only 0.008 Ohm) pump up the power until he
achieves an antennacurrent of 11 A. That will probably take a few kW but at
the end he will have also 1 Watt ERP.
If he is running sufficient power the 'little boy' will be heard as loud as
the 'big guy'. The last one will either have to accept this physical facts
or have to exceed the 1 W ERP limit (and breaking the law) to overwhelm the
'little boy'.
To make a long story short : having a big antenna is a great help to get to
the 1 W ERP limit without needing a big PA, but within reasonable limits a
smaller antenna can be compensated by running more power.
That is the fun (or for some the frustration) due to the 1 Watt ERP limit.
73, Rik ON7YD
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