[TowerTalk] Radials, lightning ground, RF ground

[K4SAV]

K7PUC wrote:
It seems to me that it takes two to tango,  The radiation from the vertical
member radiates because of the changing current but the changing current in
that lead must be balanced by an equal (but opposite)  change in current in
the other lead i.e. ground.  If that is true then at all times half of the
transmitter power must be going into the ground (?????).


You started off correct, but jumped to an incorrect conclusion.  If the 
resistance in the two parts of the antenna (vertical, and ground 
portions) was the same, then your statement would be true.  If you make 
the resistance in the ground portion of the antenna low, then there is 
going to be less power dissipated in the ground (current is the same 
remember). Think of P=(I^2)R.

Jerry, K4SAV

Al Williams wrote:

>>----- Original Message ----- > Let me try to help clear the confusion. to 
>>the best of my understanding.
>>    
>>
>
>  
>
>>1) RF COUNTERPOISE/GROUND SCREEN. A set of radials or mesh to help an
>>antenna (usually a vertical) radiate more efficiently with fewer ground
>>losses is an RF counterpoise or ground screen.
>>    
>>
>
>The concept of ground losses for vertical antennas seems unclear to me 
>although I am aware that it has been accepted for many, many years.  I refer 
>only to ground current return and not to currents generated by reflection 
>from the ground.
>
>It seems to me that it takes two to tango,  The radiation from the vertical 
>member radiates because of the changing current but the changing current in 
>that lead must be balanced by an equal (but opposite)  change in current in 
>the other lead i.e. ground.  If that is true then at all times half of the 
>transmitter power must be going into the ground (?????).
>
>It then seems to me that improving the ground characteristic with radials, 
>etc. increases antenna efficiency by allowing the vertical radiator to have 
>more changing current.  At the same time, the ground system has more 
>current, hence "heating the ground" but that is incidental and not the major 
>cause for the improvement of radiation.
>
>Thus, improving the ground system doesn't reduce ground losses but actually 
>heats up the ground more (????????) but at the same time allows the vertical 
>member to radiate more.
>
>What is wrong with this thinking?
>
>k7puc
>
>
>_______________________________________________
>
>See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
>
>_______________________________________________
>TowerTalk mailing list
>TowerTalk at contesting.com
>http://lists.contesting.com/mailman/listinfo/towertalk
>
>  
>