[Elecraft] Inverted L for 160 meters

[Dave Sublette]

The title is actually "HF Antennas For All Locations", not to be critical.
It is a classic and well worth having.

Dave, K4TO

On Wed, Aug 26, 2020 at 7:40 AM Victor Rosenthal 4X6GP <k2vco.vic at gmail.com>
wrote:

> 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
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to k4to at arrl.net