[TowerTalk] 160m vertical and the number of radials

[Pete Smith N4ZR]

Understood, Jim. Interestingly, I just found out that the ground 
conductivity in my area is probably very good, on the order of 2-4 
millisiemens, which may reduce the need for a huge number of radials.  
In this evening's 160 contest, I've been pleasantly surprised by how 
well the antenna works.  It's past time to get my receiving K9AY loop 
back in service

73, Pete N4ZR
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On 12/2/2022 5:51 PM, Jim Brown wrote:
> On 12/2/2022 12:21 PM, Pete Smith N4ZR wrote:
>> I just added 5 more radials to the 13 I had originally under my 
>> inverted L, and the R dropped from 34 to 31 ohms. Barely still worth 
>> doing, I guess.
>
> It all depends on the difficulty/cost of adding more. The radiation 
> resistance of a vertical, which represents radiated power, is a 
> function of the vertical height, not the total length. There's a graph 
> of this in my tutorial. The combination of radiation resistance and 
> ground loss, both in Ohms, forms a voltage divider for the transmitter 
> current, and power lost is 10 log of the divider ratio. If, for 
> example, you have 50-60 ft vertical, radiation resistance is likely to 
> be less than 8 ohms.
>
> 73, Jim K9YC
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