[Elecraft] Inverted L for 160 meters

[Victor Rosenthal 4X6GP]

I forgot to add: two shortend, elevated radials, fed as described below, 
is only slightly poorer (about 1 dB) than four.

73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
CWops no. 5
http://www.qsl.net/k2vco/
.
On 26/08/2020 14:36, Victor Rosenthal 4X6GP wrote:
> Kevin,
> 
> My advice is to get Moxon's book, "Wire Antennas for All Locations." 
> Follow his advice, which is (roughly): use four elevated radials at a 
> level higher than an Elk's antlers. Make the radials equal in length, 
> about 0.15 wavelength long, connect them together, and add an inductance 
> in this common ground lead to resonate them. This helps equalize the 
> currents in the radials, which keeps your radiation angle low.
> 
> Do not use buried radials unless you have room for at least 16 of them. 
> In that case they can also be about 0.15 wl long.
> 
> 73,
> Victor, 4X6GP
> Rehovot, Israel
> Formerly K2VCO
> CWops no. 5
> http://www.qsl.net/k2vco/
> On 26/08/2020 3:31, 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