GETTING ON THE LOW BANDS
A Limited Space Antenna
for 160, 80 and 40 meters
By Sean, 2E0BAX
Graphic Intensive. Allow time to
now been licensed for four years and during this time I have enjoyed
many aspects of the hobby, which ranges from operating on many
different bands and modes including SSTV and Satellites.
As those sunspots kept getting
lower in numbers and the higher HF bands were opening less and less
I found myself looking more at 40m, 80m and 160m or top band as its
known. So I put up an inverted V for 40m and this was a squeeze
where I live but it was resonant and works very well with a feed
point at 22ft above ground.
See photos below.
Thats the 40 meter
inverted V above and the feed point at 22 ft above ground in
the photo. Each leg is a 1/4 wave and follows the pitch of the roof
about 1ft above the tiles.
The style of house I live in is a Dormer and the
gutters are about 7ft above the ground. This is where the legs do a
90-degree bend and are tied to the gutter for about the ten feet or
so that remains. This works a treat, has a low SWR and is fairly
stealthy. You have to look for it or you would probably not know it
was there. As soon as I put it up there was no activity on 40m!
Typical, so went onto 20m, tuned it up with an ATU and straight away
worked a station in Kuwait! Now its cut for 20m, is fed with coax so
theres going to be losses there and who knows how much of my 50w was
That's 40m taken care of with a resonant antenna that
works very well so where do I put a half wave dipole for 80m? I can
only just get a 40m dipole up and now realizing how good resonant
antennas are over random / long wires, there is no going
On the subject of random and long wires, I have
used both, but more along the lines of random here at home. Dont get
me wrong, they work and they get you on the air but as I have found,
they can come with a cost. First thing was RF all over the place
namely in the shack with chatting relays and the PSU tripping out
making any thing above 17m a no no.
Secondly, TVI to the neighbors on 80 and 160m.
Doublets were never going to fit that would get me on
80m so it was back to the drawing board and a look at what was being
used by other Hams in such a position.
I did'nt fancy using
loading coils or shortened commercially made antennas besides wheres
the feeling of accomplishing something unless you have had some real
In one of many experiments later I decided to lay
a piece of wire mesh on the lawn and pinned it down with some bike
spokes bent like tent pegs. These were very kindly donated by M3PZO.
The mesh is about 6ft long and 18 inches wide. I then cut a length
of wire for 20m and sloped it to the low gutter, tied it off
and checked SWR. It was below 2:1 without any cutting, so I thought
I would try it with 50w. I worked all over Europe with
ease and to my surprise this antenna fed against the
ground worked. I thought you needed a high feed point or at least
get it as high as possible? Not if your using the earth as half the
antenna which in its self has just halved the size of a half wave
dipole and seems to work well without using the ATU therefore
reducing losses in the ATU and the coax feeder as it has something
around 50 ohms at the feed point.
So there you have some
"history" behind my thoughts for getting on 160 and 80 with my
limited space.......All of the above experimentation led up to where
I really wanted to operate more....the 160 and 80 meter
Now on to experimentation with the 160 and 80 meter
This is how I did it in the
Here is a drawing above showing the 80/160m
antenna. I cut the 80m leg at 67ft and trimmed for best SWR at
3.5mhz (UK bottom part of 80m). Due to the narrow bandwidth on a
wire antenna on 80m you will need to use an ATU. The feed point is at ground level and the
radiating wire goes up over the house and into a top room window
where I have a crocodile clip (acting as a switch), to attach
the 160m section.
The 160m leg is another 63ft and has a loading coil
4ft long with about 40ft of wire space wound on it to
reduce the length as I was pushing getting this thing on my small
footprint of land. The remaining length, about 10 feet, goes up
to the ridge of the roof where the 40m inverted V is mounted.
Here is the earth matt above in the
photo ,about 1 1/2 X 6 feet, and you may need
to do more than this depending on where you live and your ground
situtation. The feed point is on the left lower corner out of
the picture.....I'm lucky, I live on very wet ground. It's a peat
bog and in fact my house is on a concrete raft and known as a
Bury wire if you need to and check out your ground
conditions. Having that other half of the
antenna "in the ground" is a very important part of making this work
You may need several earth rods several feet long.
Experimentation is the best!
Inside the window, I am on 80m with the crocodile
clip not connected.
You might call
this a poor man's antenna switch...but it works great!
With the clip lead coming from the 80 meter end and
connected to the 160 meter section in the photo above, now I am
resonant on 160m with a loading coil that I couldn't avoid.
clip connects the 80 meter end to the 160m section with the coil in
line up on the roof. It works!....... and better than I thought it
The loading coil is pictured above up on the
length is 67ft.......
The 160m length (physical
length) 90 feet.
It's construction consists of about 40 feet of wire
wrapped around the 4 foot form with around 63 feet total
of wire used in the complete 160 meter addition to the
antenna. When you add the 80 meter length to this, you
get about 130 feet total wire used with the 80 and 160 section
Total length is 130ft of wire for 160m reduced to
90ft due the loading coil.
Again I went for resonance on
the lowest part of the band. This will take some experimentation
with the placement of the coil and the total length of the wire at
your location. You need to experiment here as the SWR can change a
lot with the surroundings.
Using this antenna I have worked all
over the UK on top band with as little as 20w making me one happy
chap! So if you need a restricted space antenna for getting on the
low bands...give this method a try and with some
experimentation....See you on 80 and
160....73 Sean! 2E0BAX firstname.lastname@example.org
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