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