eHam
eHam Forums => Antennas, Towers and more => Topic started by: KF0GYT on March 23, 2023, 09:58:51 AM
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I have a 30 foot Flagpole (not up yet). The plan was to get a second one and string up and Buckmaster or maybe a Palomar OCFD between the two with the feed line dropping right outside my shack wall, then going in...
In my never ending journey of looking at and experimenting with different Antennas, I stumbled upon Sky Loops.
I stumbled onto it looking for the right solution for me and my property.
It seems like every antenna has its plusses and minuses...
I want to be able to work as many bands as possible (6, 10, 20, 40, 80, (160 as a bonus and any bands in between the ones I mentioned I guess).
But I don't want to have 6+ antennas. I want as few as possible. Like most, I'm sure.
I have a decent sized (2+Acres) field/yard, with lots of crap in it (to get in the way of radials), but distance or length of wires up hightshould not be much of an issue up at 25-30'.
My biggest issues is height.(everything wants to be 45-87' High. I get it, but its not going to happen here.
Not many good trees that are high enough or solid enough at 20-30' or Higher or in places were I want them to hang something from them.
That's why I bought the 30' Flag pole as a starting point to hang an antenna wire from.
For the Sky loop, I could purchase 3 more, one for each corner, then be able to pull up a corner of the wire to height and get a full wave vs a 1/2, 1/4, or something lessor.
Would this work for DXing. I currently have a simple 10m Dipole on a temporary/portable tripod with 2 10m Hamsticks.
Seems like from Southern Missouri I am reaching Colorado, Montana and Washington. Picked up a guy loud in clear near Ukraine, but he could not even hear me.
I'm looking to hear and reach much further, than I am now.
Thanks for any input
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You will receive many answers to your question and here's mine. You now have a 30' flagpole, want to operate as many bands as possible and cannot easily install ground radials. I suggest you look into a coax fed trap dipole mounted as an inverted-vee. The Diamond W-8010 operates on 80, 40, 20, 15 and 10 meter bands with a half wavelength antenna on each of those bands. As such it exhibits a dipole azimuth pattern and only the radio's ATU is needed.
W-8010 https://www.dxengineering.com/parts/dmn-w8010
I don't favor OCF and end-fed antennas due to their numerous azimuth nulls and issues with common-mode current on the coax. I don't favor center fed Zepp antennas because of their numerous azimuth nulls and having to manually tune with each band change. Note that you do gain the WARC bands. Sky Loops are good antennas but require four stout supports.
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I put up an 80M full wave loop. It was a great antenna for 75M SSB short skip contacts. The wires were a little higher than you propose, but not by much.
It was typically inferior to a center fed 86 foot dipole at 35ft aimed at Europe or a 33ft vertical end fed wire when working DX.
For many hams 80M DX is hard and 160M DX even harder.
I have a top loaded vertical on 80 that works well and an Inverted L for 160 that is usable for working DX.
My multiband dipoles don't include 80 meters--just 7MHz and up.
Single band Half Squares for 30 and 40M have worked well into Asia from Connecticut.
One lucky morning I worked Nepal on both 40 and 30 with Half Squares.
DXing can be hard because you are often competing with a lot of other hams trying to work the same station.
But, sometimes you can get lucky on CW. There are a lot of DX-peditions right now.
I had a three minute CW exchange with Kanti VU2GSM in India on 30 CW last night while folks were busy chasing CY0S and 9X5RU.
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Good choice. See my article in Practical Wireless March 2023 issue on HF horizontal loops.
73,
Frank
K4FMH
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I've used a number of horizontal loops over the years, and they
can work well, even when the shape isn't a nice tidy regular
polygon. On some bands and in some directions they are
stronger than a dipole, in other directions they might not be.
Here is a collection of radiation patterns (https://practicalantennas.com/theory/loop/large/) for different shapes,
bands, and feedpoint locations.
Just like a dipole, the vertical angle of radiation is strongly
affected by the height above ground.
More loop articles (https://practicalantennas.com/designs/loops/).
The Field Day Loop article (https://practicalantennas.com/designs/loops/80m-fd-loop/) shows an antenna that I used
for several years, that worked quite well with QRP. Note
that it also had the advantage of ground slope near the
top of a hill. I specifically chose that shape to align the
major lobes in useful directions.
The Bow-Tie Loop (https://practicalantennas.com/designs/loops/bowtie/) shows one option for installing a loop
on a single support: I used a ~28' center mast and tied
off the 4 corners to posts about 12' high. It would have
been better to get the ends higher, but that was what I
could easily manage at the time.
So if you are short on supports, you might consider one
of the delta varieties, or elevating two opposite corners
of a square loop.
Now, let's consider some trade-offs.
Height makes a big difference for working DX with
horizontally polarized antennas. If you have to invest
in supports, consider whether it makes more sense to
use just one taller mast (either in the center of a loop,
or to support an inverted vee) rather than several
shorter ones (for the corners of a loop).
For example, I have 100' of the military 4' mast sections.
I can put each corner of a square loop up 24', or I can
put up a single mast about 40' high (limited by what I can
manage by myself, rather than the amount of mast).
My guess is that, except possibly in some specific directions,
the 40' inverted vee is going to work better than the lower
loop for DX.
That's not to say that you won't work DX with the lower loop:
you can, especially as conditions pick up compared to the last
couple of solar cycles. But the higher antenna would likely be
a little bit better in many cases.
When you are limited to particularly low heights, then vertical
polarization may work better than horizontal. You can hang
a vertically polarized delta loop off a single support, although
they tend to work best over a more limited range of bands.
Other options include the heavy duty fiberglass masts from
MGS (https://mgs4u.com/fiberglass-push-up-masts/), which go up to 50', or the telescoping SpiderPoles (https://www.dj0ip.de/spiderbeam/fiberglass-spiderpole/),
which are available up to 85' (although the top section isn't
useful for much besides supporting a very light vertical wire).
You likely will need guy ropes with the taller masts.
(MFJ sell masts similar to the MGS ones, for about the same
price, and you may be able to save on shipping costs if you
can order it through a local Ham Radio distributor. Check with
the store and see.)
Now, another thing to consider is the effect of a sloping wire.
With an 1/2 wave inverted vee (or dipole), maximum radiation
is from the high point of the antenna. That makes good use of
your available height. As the wire is made longer, particularly
for multi-band operation of the same antenna, you get radiation
from lower points along the wire, which lowers the average height
of the antenna. That's not as good. And maximum radiation
tends to be more towards the end of the wire rather than broadside
to it. That can be useful, but when the wire is sloping at too
steep of an angle, you lose gain because the major lobes are
aimed too low. That can be the case with an OCFD or EFHW
installed as an inverted vee, especially on the higher bands
like 15m and 10m.
My practical suggestion: first, get on the air.
Remember, no antenna is permanent. (Although some of my
"temporary" antennas have stayed up longer than my
"permanent" ones.) You can always change your antenna
if it doesn't seem to be working for you, or to try something
new. Make sure your support has a halyard (like a flag pole)
so you can raise and lower the antenna without having to
take down the support.
Start with something simple. A horizontal loop can be
great if you have 100' Douglas Fir trees to hang it from.
If you have just one support, cut dipoles for 20m and
40m and hang them as inverted vees from a common
feedpoint. Add other bands as desired. The wires can
hang below each other, or be tied off in different
directions (possibly acting as guys for the mast).
Don't get too bogged down at this point in making the
"perfect" antenna. Instead, put up a "usable" antenna
and get a feel of the bands. Day-to-day propagation
differences will be much greater than the differences
among many of the antennas that have been discussed
on this thread: all of them can work on a good day and
hear nothing at all when the band is dead.
From that you can see where you want to make
improvements. Maybe you use one antenna for 20m
through 10m, a small beam for 6m, and a vertical
for 40m DX. Or you might have a couple different
antennas that you can string up for specific
occasions: with a halyard on the mast and a center
insulator on your coax that makes it easy to change
the wires around, you can experiment with different
antennas and see which ones work best for your
specific interests. (I often hang two halyards on any
mast that I install, so I can test one antenna while
using the other.)
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I have an 80m full wave horizontal delta loop, and am working the whole world. It was initially supposed to be NVIS, but turns out to be the best all round antenna I have ever had. It is great if you have the space, and RX is very quiet.
Regards,
Marius ZS1ML,
Cape Town, South Africa.
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My skyloop ended up being 350 feet long. It is up around 60 feet. It is fed with about 75 feet of home brew ladder line which leads to a Balun Designs 4116 hybrid balun. The balun is connected to a manual tuner via a short run of coax. I use this antenna for 10m through 80m. The antenna and feed line are constructed of AWG #14 THHN stranded "house wire" with black insulation.
The antenna is more or less square except for one side, about 20 feet, that is pulled away from another pine tree. I call the geometry "assymetrically pentagonal" ;D
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hi I put up a 40M skyloop six months ago. I fed it with a 4 : 1 balun and its average height is only around 7M It works fine and I can tune it on all HF bands from 40M to 10M using my rigs internal tuner.. It is excellent on 40M, 20M and funnily 18M. I work EU and USA, SA etc every day from VK4. It is a bit deaf on 30M but still can work the USA on digital. 15M, 17M and 10M all work ok but not steller. It is very quite on receive and for its low height transmits very well. I find it a great all rounder antenna
Wayne VK4WTN
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I like the loop. And fed with window line and a tuner makes a great multiband antenna. It does not have to be cut to frequency, but bigger is better up to a point. There are better smaller antennas for VHF/UHF.
-Mike.
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I like the loop. And fed with window line and a tuner makes a great multiband antenna. It does not have to be cut to frequency, but bigger is better up to a point. There are better smaller antennas for VHF/UHF.
-Mike.
Multi-band loop as the best option if beam based antenna installation is not possible. Make if window line fed to ground level and then use remote tuner between it and coax going to your station.
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With the right dimensions, using a 4 : 1 balun
at the feedpoint and coax to the shack can
work pretty well, too. The SWR will be low
enough on many bands that losses are
reasonable, and an internal autotuner will
often match it.