[TowerTalk] Grounding?

[Grant Saviers]

Hi Steve,

Unless there is something highly conductive "down there" to connect to, 
I don't think ground rods make much RF difference anywhere in a lower 
loss radial system for a vertical antenna.  Then for lightning 
protection the 2 length separation between rods seems correct to me. 
Then inductance in the wire limits the practical lightning protection 
wire length to around 60 ft, so no point in setting ground rods further 
out from the base.  I also found that #2 solid wire (new code) to 
connect pairs of 8' rods (for lightning protection) 16' apart has enough 
surface area to reduce measured resistances in a 32' long radial pattern.

For a new tower base, making it a Ufer system with the rebar well 
connected to the grounding plate, IMO probably does more than several 8' 
ground rods for lightning protection.  At least my ground resistance 
measurements seem to show that.  Is there some RF benefit?  At least 
damp concrete with rebar has much more conductivity than average ground.

Grant KZ1W


On 3/27/2019 13:37 PM, k7lxc--- via TowerTalk wrote:
> Howdy, TowerTalkians --
> 
>      In a vertical xmit antenna, is there a compelling reason to use ground rods near the antenna (vis-a-vis tower lightning grounding) in addition to radials? If you have a number of radials going out from the tower, do close ground rods add anything signal/efficiency-wise? Tnx.
> Cheers,Steve      K7LXC
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