Topband: 160 meter L

[Joel Gray]

> 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 <joelgray77 at gmail.com> 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 <n0jk at hotmail.com> 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
>>
>
>