> I have a 75-80 1/4 wave vertical. It has 20 1/4 wavelength radials. I > would like to run an inverted l up the radiator and horizontal for the rest > of the radiator both antennas fed with same feed line. - Doug. WD8Z
I started out with a 1/4w inverted L on 160, about 55' high, the rest horizontal. I added an L network at the base for a better match given my longish feedline. I later added a 1/4w 80m vertical spaced about 2 feet away with pvc spacers. Actually, the last 10-15 feet are bent over like an inverted L also. They share the same feedline, and the 80m antenna connects before the matching network. I do not use any relays to switch between them, both are always connected. The modeling I did (4nec2) showed that each antenna presented a relatively high impedance on the other band. I viewed this as similar in principle to a fan dipole. I do not know whether the pattern is significantly affected by this or not. With the 2 foot spacing, I did not have to make any significant adjustments to the 160 inverted L. I cannot say whether closer spacing would work. I assume it would, although there would most likely be more interaction. I use a good common mode choke on the feedline (overkill perhaps?). Both antennas load up nicely. Although I can't really measure field strength, I can say that adding the vertical on 80m increased my country count fairly quickly so it is working better than my inverted V at 55 feet. My 160m performance doesn't seem to be affected at all. Good luck with it! 73, Joel N9LQ On Thu, Mar 23, 2017 at 2:26 PM, Joel Gray <[email protected]> wrote: > > I have a 75-80 1/4 wave vertical. It has 20 1/4 wavelength radials. I > > would like to run an inverted l up the radiator and horizontal for the > rest > > of the radiator both antennas fed with same feed line. - Doug. WD8Z > > I started out with a 1/4w inverted L on 160, about 55' high, the rest > horizontal. I added an L network at the base for a better match given my > longish feedline. I later added a 1/4w 80m vertical spaced about 2 feet > away with pvc spacers. Actually, the last 10-15 feet are bent over like an > inverted L also. They share the same feedline, and the 80m antenna > connects before the matching network. I do not use any relays to switch > between them, both are always connected. The modeling I did (4nec2) showed > that each antenna presented a relatively high impedance on the other band. > I viewed this as similar in principle to a fan dipole. I do not know > whether the pattern is significantly affected by this or not. With the 2 > foot spacing, I did not have to make any significant adjustments to the 160 > inverted L. I cannot say whether closer spacing would work. I assume it > would, although there would most likely be more interaction. I use a good > common mode choke on the feedline (overkill perhaps?). Both antennas load > up nicely. Although I can't really measure field strength, I can say that > adding the vertical on 80m increased my country count fairly quickly so it > is working better than my inverted V at 55 feet. My 160m performance > doesn't seem to be affected at all. Good luck with it! > 73, Joel > N9LQ > > > On Thu, Mar 23, 2017 at 1:29 PM, jon jones <[email protected]> wrote: > >> I fly a balloon vertical for 160 meters (1/4 wavelength) with 8 radials. >> >> For 80 meters I use a standard tuner right at the base feed point to >> match it = ~ 1/2 wave. It gets out quite well. Voltages would be >> high so use appropriately rated coils/capacitors. This may be another >> option for a two band inverted L if one does not wish to use a trap. >> >> - Jon N0JK >> >> >> > I have a 75-80 1/4 wave vertical. It has 20 1/4 wavelength radials. I >> > would like to run an inverted l up the radiator and horizontal for the >> rest >> > of the radiator both antennas fed with same feed line. - Doug. WD8Z >> >> >> _________________ >> Topband Reflector Archives - http://www.contesting.com/_topband >> > > _________________ Topband Reflector Archives - http://www.contesting.com/_topband
