[TowerTalk] Beverage Antenna Mounted 12' Above Gorund

[David Gilbert]

Hi, Jim.

Well, by "RF ground" I meant the conductive (actually semiconductive) 
zone of the earth as seen by the incoming RF relative to the wire.  
"Ground" is the same term used in modeling programs like EZNEC, and I 
qualified it by saying RF since the conductivity is different at RF (HF) 
than, for example, DC or power line AC.  I certainly did not mean in the 
context of an infinite source or sink of electrons like some folks seem 
to think exists.

I could have been more precise, though.

73,
Dave   AB7E



On 8/31/2021 10:00 PM, Jim Brown wrote:
> Good analysis, Dave. Beverages depend on lossy soil underneath them to 
> work, and, as we all know, soil varies widely from place to place, and 
> even locally. I have very poor (rocky) soil, and the terrain under it 
> in my woods is quite irregular. For example, my EU/VK reversible Bev 
> starts at about 5 ft, running over the earth that drops gradually and 
> then more steeply to to a creek, losing about 30 ft of elevation, then 
> climbing up a steep rise to its termination point. Over that run, it's 
> height above ground varies from five feet to 10-12 feet. For most of 
> its length, it's held up by laying on top of brush.
>
> As 160M super-op has often said, "any Beverage is better than no 
> Beverage." His run through terrain at least as irregular as mine, and 
> he's deep in a ravine!
>
> I do, however, object to "RF ground," and so do authorities like N0AX 
> and K6WX.
>
> 73, Jim K9YC
>
> On 8/31/2021 7:58 PM, David Gilbert wrote:
>>
>> Since actual RF ground could be almost anywhere (and could be 
>> definitive or graded) depending upon your soil, practically speaking 
>> the difference between 12' and 10' is a meaningless distinction.
>>
>> The height above actual ground will of course moderately affect the 
>> input impedance, but you're not going to know what that is ahead of 
>> time and to be rigorous you would want to adjust the terminating 
>> resistance for a more or less constant impedance as a function of 
>> frequency ... and then set the turns ratio of the coupling 
>> transformer to match.
>>
>> Personally, I think being THAT rigorous isn't all that rational. Put 
>> your wire at 12' and use whatever input transformer and termination 
>> you already planned.
>>
>> 73,
>> Dave   AB7E
>>
>>
>>
>> On 8/31/2021 5:56 PM, RVZ via TowerTalk wrote:
>>> Wondering if anyone has had good success with a Beverage mounted 12' 
>>> above ground?  12' is the minimum clearance I need to safely clear a 
>>> drive way.  Please reply direct as I hope to install tomorrow.
>>>
>>> Thanks in advance for your reply! 73, Dick- K9OMRLVZ at aol.com
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk at contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk