[Elecraft] Inverted L for 160 meters

[David Gilbert]

If you are going to go with buried radials, I don't think 4 or 5 of them 
is going to do a very good job for you.

Like N7WS recommended, look up N6LF's work and read it carefully. Seriously.

73,
Dave   AB7E




On 8/25/2020 5:31 PM, kevinr wrote:
> I have to be very careful of raised wires on my property.  If they are 
> not above the height of an elk's antlers I am in trouble.  I plan to 
> bury them.  This is something I've never done before which has its own 
> merit.  I have plenty of wire scrap from broken antennas so the 
> non-resonant, buried radials work better for my circumstances.  I need 
> to calculate the feed point impedance to see if I need to design a 
> balun for the system to work.  Once my main project is done I'll have 
> more time for modeling each method.
>
>    Thanks for all the ideas guys,
>
>        73,  Kevin.  KD5ONS
>
>
> On 8/25/20 5:23 PM, Wes wrote:
>> You probably should get acquainted with Rudy Severns, N6LF. 
>> (https://www.antennasbyn6lf.com/)  He has written more than you ever 
>> want to know about vertical antennas,
>>
>> More specifically to your case, are you planning the radials to be 
>> elevated?  If so, they need to be the same length, in fact some 
>> effort should be made to get all of the currents the same. The last 
>> thing you want is a fifty ohm feedpoint impedance with a shortened 
>> vertical (which is what an L is).  There is evidence that elevated 
>> radials are an improvement over on-the-ground or buried radials.  
>> Mine are on the ground, mainly because 1) I didn't want to give up 
>> radiator height to raise the radials, 2) all of the big guns bury 
>> theirs and I don't have room for full length radials anyway in my 
>> cactus patch.  See my QRZ page for evidence.
>>
>> My modeling shows a little bit of directivity away from the 
>> horizontal wire, but it's negligible.
>>
>> Wes  N7WS
>>
>> On 8/25/2020 4:23 PM, kevinr wrote:
>>> From what I can find, and what I can calculate, five wires, each 
>>> ~130 feet long, could make a nice inverted L for 160 meters.  One 
>>> leg for the vertical and horizontal portion of the antenna.  Four 
>>> legs for the counterpoise (ground plane).  There are many broken 
>>> wire antennas stored in my shed which are fodder for the radials. Do 
>>> all of the legs for the counterpoise need to be 1/4 wavelength or 
>>> can I substitute some shorter lengths?  The feedpoint should 
>>> somewhere above 50 ohms impedance.  As I add more radials that 
>>> number will reach 50 ohms asymptotically.
>>>
>>> I can get the vertical part up to 70 or 80 feet above ground with 
>>> the rest of it horizontal.  Most of the radiation should take place 
>>> from the vertical part since it is closer to the feed point.  But 
>>> there should be some effect from the direction of the horizontal 
>>> portion.  How strongly does the direction of the horizontal portion 
>>> effect the radiation pattern of the antenna system?  My property 
>>> allows me to point it from 300 degrees around to 200 degrees so I 
>>> have plenty of options.  Between 200 and 300 degrees there is a road 
>>> used by loggers, and the folks maintaining the towers at the top of 
>>> this mountain.  They can break any antenna lower than 80 feet above 
>>> ground.  Spar poles and cranes clear out any dead limbs across the 
>>> road.
>>>
>>> Inquiring minds...
>>>
>>> Kevin.  KD5ONS
>>>
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>>
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