[Elecraft] Need help from an EZNec user on a horizontal loop question
Barry
k3ndm at comcast.net
Sun Jan 1 22:23:19 EST 2017
Don,
Good suggestion. Let me suggest a variant that at least two of use
are using. I use it because of my severe space limitation. Basically,
the antenna is an inverted L that is fed at its center at the top of the
vertical run thereby obviating the need for a ground. It has a total
length of a about 1/2 wave, but half is vertical, or nearly so, and the
rest runs to a convenient tree that is a little lower than the tree
holding up the vertical piece. I feed it using 450 Ohm ladder line to a
4:1 current balun where I transition to coax.
I ran an Eznec simulation of this antenna. It appears to play really
nicely on 80-30 meters, and the lobes get a little crazy starting at
about 20 meters. On the air, performance appears to agree. The downside
of this antenna is the vertical piece is susceptible to local man-made
noise. This is far from a perfect antenna, but I sure can work DX and
locals.
Let me restate that this is not a perfect antenna. I started down
this road as the upper bands are not going to be great as we slip lower
in the solar cycle and I wanted to get DXCC on 80 and 40. This antenna
does lay down a low lobe on both bands and losses are reasonable. A good
horizontal antenna will have a higher radiation angle at the support
heights I have. This is my way of dealing with the problem of getting
low angles with reasonably high supports. If I had 100+ foot supports
around, I might look at some other option.
73 & Happy New Year,
Barry
K3NDM
------ Original Message ------
From: "Don Wilhelm" <donwilh at embarqmail.com>
To: "Terry Brown" <n7tb at comcast.net>; elecraft at mailman.qth.net
Sent: 1/1/2017 9:44:06 PM
Subject: Re: [Elecraft] Need help from an EZNec user on a horizontal
loop question
>Terry,
>
>Have you considered an 80 meter inverted L?
>
>It takes up little real estate for the radiator, but does require
>putting down a ground screen at the base of the inverted L.
>If you do not wish to bury 32 radials for a ground screen, consider
>using resonant elevated radials. Two elevated radials running in
>opposing directions will do the job nicely.
>
>Put the elevated radials above ground by about 10 feet to keep them out
>of the range of humans and deer and other things running into them and
>causing harm. If there are horse riders who will be riding through
>your property, you may want to increase the height to 15 feet.
>
>73,
>Don W3FPR
>
>On 1/1/2017 4:55 PM, Terry Brown wrote:
>>I am moving from my current QTH where I have a horizontal loop up
>>about
>>35-40 ft. that is a bit longer than 1 wavelength on 80. I feed it at
>>one
>>corner with 450 ohm twin lead connected to a 4:1 voltage balun, then
>>coax to
>>my rig. I can tune all the ham bands either barefoot to my K2 or KX3
>>and
>>the KXPA100 using their internal tuners.
>>
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