[TowerTalk] QST SEP 2000

[Tom Rauch]

> I saw an article about W5UN with 1.5 million watts ERP on 2 meters into a
> 30 dbd array.  How far does he have to move his house (shown on the cover
> next to the antenna) to be in compliance with the new radiation rules? 
> (you wouldn't expect him to lower his power would you?) 73, Ken W2DTC

When the physical size of the array is large compared to the 
distance of measurement, and current or "power" is distributed 
somewhat evenly in the array, the field intensity is actually less 
than with a smaller array with the same applied power. 

Visualize the radiation of 1500 watts of energy (that's the MOST 
power you can have, no matter what the antenna "gain" is) from 
that large antenna, and the portion of it concentrated in a small 
area as you move around in front of the array. Most of the radiated 
field "misses you", and it acts like you are in front of an small 
section of that antenna with much lower applied power.

At a distance where that antenna starts to "look like" radiation 
comes from a single point in space, all of the energy arrives in 
phase.

He is much more likely to be in trouble at his neighbor's house 
than his own, but I doubt he points the antenna along the ground.

He'd have far more FS in a small area of his house with a small 
array pointed at a small area of his house than that big array in the 
back yard pointed at the entire house and overlapping the sides. 
73, Tom W8JI
w8ji@contesting.com

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