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Author Topic: What's a good next antenna to use?  (Read 17357 times)
KA0HVE
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Posts: 117




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« on: July 31, 2013, 09:11:30 AM »

I live in south-central Iowa and have quite a bit of space for an antenna.

In your expert opinions, which direction(s) would be most advantageous for me to direct my signal?  (I was thinking NE and SW.)

I want to keep the cost down so what sort of antennas would you use for a fairly inexpensive set up?  (I was thinking a doublet inverted-v for 10 through 80 meters but I'd be forced to direct the signal more N and S or E and W depending upon where I put it in relation to the house.)

I hesitate to install a ground mounted vertical since it would be lower than the land just to the N of the house plus the house would be in the way of the signal going N.

The inverted-v doublet would be more omnidirectional and up fairly high so it should be equally good (or equally poor) in all directions.

A long wire pointed S would have a great open area since the land slopes downward as you go S and you can see above the trees and farm land for miles.

So, what are your suggestions?

I've always thought there was a lot of value in the old adage, put up as long a piece of wire as you can as high as you can, cut it in the middle, and feed it with balanced line.

Thanks!
« Last Edit: July 31, 2013, 09:20:19 AM by KA0HVE » Logged
K8AXW
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Posts: 3910




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« Reply #1 on: July 31, 2013, 09:22:15 AM »

Since you seem to be oriented toward an inverted V of some kind, this means that you have or will have a suitable center support..... mast or tower.

If this is the case, may I suggest an inverted Double Bazooka?  Although one is in the works, I have never used one but have read only good things about this antenna.

With that being said, with the inverted V (standard or Bazooka), you have the option of swinging the antenna around on it's apex to see if you get better results in any particular direction. 

Although the antenna is supposed to be omnidirectional, this isn't always the case.
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KA0HVE
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Posts: 117




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« Reply #2 on: July 31, 2013, 09:26:29 AM »

Yeah, I'll need to buy support(s) of some kind.  A few years ago we built our house on part of a hay field so no trees of any significant height yet.
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WB6BYU
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Posts: 13355




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« Reply #3 on: July 31, 2013, 10:33:04 AM »

You can print out an Azimuthal map based on your location from NS6T's site here:
http://ns6t.net/azimuth/azimuth.html

Then you can overlay it with plots of the patterns from different antennas to see
what areas they cover and where they have nulls.


One important consideration is your operating interest - you likely would choose
different antennas for rag chewing on 40m or working DX on 15m, for example
(though there could be antennas that work well for both.)  Sometimes the best
solution is multiple antennas, especially for multi-band operation.


I've used a lot of antennas over the years.  Long wires tend to be more directional
off their ends, but can be useful when pointed in general areas (such as Europe
or VK/ZL).  But performance drops when it is too long - I've had best results around
135' or so.

For working DX you want low angle radiation - that typically means getting the
antenna up in the air (ideally 1/2 wavelength or more) or using vertical polarization.
With a 40' support, for example, you likely will have better results working DX with
a horizontal antenna on 20m and higher frequencies, a vertical on 80m and 160m,
and the option to try both polarizations on 40m.

Center-fed doublets can be useful multi-band antennas, but performance drops off
on the higher bands when they are installed in an inverted vee configuration.  The
steeper the slope of the wires, the more the impact.  If you are primarily interested
in 80m and 40m, this probably isn't an issue, but if good performance on 15m and 10m
is important then you'll want to install it as flat as possible, or use a trap dipole instead
so only the center portion is used on the higher frequencies.

I've also had good results with large horizontal loops for multi-band operation, but that
will require more supports.  And I've worked a lot of DX using a simple dipole or inverted
vee.

On the other hand, a vertical might not be such a bad choice:  the local terrain might
not be as bad for propagation as you think.


So my suggestion is to try several different antennas.  A simple vertical - even if it is
just some stray irrigation pipe or wire held up with a length of 2x4 - will give you a sense
of what you can expect from that polarization.  A quarter wave on 20m is only 17' or so
(and you can shorten that if needed) so it isn't difficult to experiment.  Keep your eyes
out for some inexpensive supports - a TV push-up mast should get you up over 30',
irrigation pipe can be spliced together, or you may find a neighbor with an old over-the-air
TV antenna on a tower that is no longer in use.  Put a couple pulleys and halyards on the
top so you can change antennas without having to lower or climb it.  For long antennas
you might need end supports high enough to let the hay trucks through underneath.  Then
put up a couple antennas and see how they work.  Remember, no antenna is permanent!


But if you want a single antenna that can serve a number of uses, consider a 40m Bobtail
Curtain.  Instead of the standard center wire, feed it with open wire line in the middle
like a doublet.  Face it broadside to your desired direction.  At the base, arrange a switch
or jumper lead so that you can either feed the open wire line in the normal manner, or
short the two conductors and feed it against ground.  Yes, it will require some sort of
impedance matching, and some autotuners might complain about matching a high
impedance load (depending on the exact dimensions.)  For initial testing you can walk out
to the feedpoint and move a clip lead.  But that gives you a multiband antenna with two
different sets of radiation patterns to experiment with.
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W1JKA
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Posts: 1778




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« Reply #4 on: July 31, 2013, 11:52:29 AM »

If space is no problem and you are considering an inverted Vee you might want to think about a bi directional one that can be switched with a cheap 12V dc Rat Shack relay. FWIW I built one for 30 meters only, the major advantage for me is most always a better signal (less noise) on one or the other by switching them no matter what direction the station is from.
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KK0G
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Posts: 47


WWW

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« Reply #5 on: August 02, 2013, 07:45:48 AM »

In my experience unless you get a dipole up in the air a significant height, as in 1/2 wavelength or more, there will be little if any directional gain. Even if you're able to mount it high enough to show gain we're not talking about a lot of gain. In addition a multi-band dipole covering 10-80 meters can only be mounted at a height that's optimal for a single band anyway.

Personally I'd just mount in what ever orientation allows me to get it as high as possible with the least amount of cost, effort, etc. If you need a hand raising it give me a call. 73

Chris

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W5LZ
Member

Posts: 477




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« Reply #6 on: August 13, 2013, 06:02:58 AM »

I have to agree with KK0G, most antennas (wire) on the lower HF bands just aren't going to be high enough to be very directional.  Some, maybe, but nothing really exceptional.  For the lower HF bands (20 and under?) an inverted 'V' doesn't make for any super sensational performance.  It's big attraction is that it only requires one sort of tall support.  That 'droop' is also an easy way to get the feed point impedance closer to 50 ohms and still maintain the antenna's resonance.
And in the end, you will always be dependent on 'Momma Nature's propagation for 'performance'.  She tends not to pay much attention to your requirements, so things are almost never 'perfect'.  (Dang!  Sounds a lot like my EX.  Oh well...)
 - Paul

The old saying, 'As high and as long as possible' tends to be true 50% of the time.  It's easier to make a 'too long' antenna work than one 'too short'.  Same for a 'too high' and 'too low' antenna.
I don't think I've ever had a 'too high' antenna, must be nice...
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ZENKI
Member

Posts: 960




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« Reply #7 on: August 16, 2013, 04:51:15 AM »

DX or Local that is the question?

80 Doublet with open wire line
Double extended Zepp

However asking 1 antenna to do all things on all bands for DX is a very hard.

If it was me I would use a 1/4 wave vertical for 75 and  40 meters DX. Verticals are operationally very cost effective.
For local use a  Skyloop or doublet for a all band antenna.

For DX from 30 through to 10 meters look up the HF Skeleton Slot by G3LDO. This antenna which can be supported by a tree or single pole and is open wire fed. Is the most effective simple high  band DX antenna that I have used. Its bi-directional  however you could probably spin it with rope if you constructed it right.

If you wanted a clean solution it would be this. A hexbeam up as high as you can on a pushup mast. A doublet fed with OWL or a skyloop. This will be enough  antennas to give you decades of fun. This combination would be cheap as well.

If you have tons of trees and  some height you cant beat V beams or rhombics . These are high maintenance antennas if not done properly.

My vote goes for the hexbeam and doublet simple and easy. Used with a small linear like a AL80 or SB220 you will  have tons of ham radio fun.






I live in south-central Iowa and have quite a bit of space for an antenna.

In your expert opinions, which direction(s) would be most advantageous for me to direct my signal?  (I was thinking NE and SW.)

I want to keep the cost down so what sort of antennas would you use for a fairly inexpensive set up?  (I was thinking a doublet inverted-v for 10 through 80 meters but I'd be forced to direct the signal more N and S or E and W depending upon where I put it in relation to the house.)

I hesitate to install a ground mounted vertical since it would be lower than the land just to the N of the house plus the house would be in the way of the signal going N.

The inverted-v doublet would be more omnidirectional and up fairly high so it should be equally good (or equally poor) in all directions.

A long wire pointed S would have a great open area since the land slopes downward as you go S and you can see above the trees and farm land for miles.

So, what are your suggestions?

I've always thought there was a lot of value in the old adage, put up as long a piece of wire as you can as high as you can, cut it in the middle, and feed it with balanced line.

Thanks!
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NEVBEN
Member

Posts: 43




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« Reply #8 on: August 30, 2013, 07:57:15 AM »

I've looked at azimuthal maps or great circles, and looked at the model at keyhole (google earth).  The latter has a handy measuring tool that will readout the distance of your arc.  Not surprisingly, I found the shortpath to nearly everywhere DX but 'down-under' is through the arctic.  I'm thousands of miles west, but at a similar latitude to Iowa.  The short paths to destinations from London across to Tokyo were at bearings between 315 and 45 degrees.  If the best path were simply a matter of the shortest distance over the surface of the sphere, our antenna would almost always be pointed generally north.  But I suspect there's more to it than just finding the bearing of the shortest distance on the surface.

If I had an antenna with significant directional gain, I might hope to tune in some distant beacons and turn it around and see by which direction I receive the best signal.  I don't.

I am not an expert on propagation at all, but I know that our transmissions don't go out as lines.  Likewise, the signals we hope to receive are broad waves.  At closer distances on the surface of a sphere it only makes sense to point the antenna at the bearing of your correspondent.  But when you're on the other side of the sphere, the shortest path is less likely to be the best criteria for selecting a bearing.  Instead, I suspect the characteristics of the D-region and E-layer and how your frequency interacts becomes more important.  So for example, there may be a weaker D-region over the polar area (unless there's a PCA event) that favors lower frequencies, whereas through the equatorial paths the D-region is strong during daylight.  But those artic routes may feature some D at all hours through the summer, and be relatively void of it in winter.  While I can speculate, only the actual conditions determine the best bearing to take.

I imagine that it makes little difference unless you've got a rotatable beam on a tower or four-square or something like that.  But I suggest opening up keyhole...

+ put a placemark (yellow push pin) on your location (from the toolbar at top)
+ then press the yellow sun icon on the same toolbar (now you see your D-region)
+ use the time slider to set the model to the times you will operate

besides those, there's also ruler and image overlay functions

Keep in mind, however, that our radio waves are not traveling across the surface of our 3D model, but they are being reflected off the ionosphere.  We know there are things like "skip" and I understand that at the greater distances there are multiple reflections off the ionosphere and the crust.  You can at least try to imagine a bounce every 4500km or so (I've read).

Maybe the next version of EZNEC will integrate with the forthcoming Google Ionosphere®.
« Last Edit: August 30, 2013, 08:00:13 AM by NEVBEN » Logged
W1VT
Member

Posts: 847




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« Reply #9 on: August 30, 2013, 08:43:27 AM »

If you have no existing supports for an antenna, a vertical will be cheaper as it only needs one support that doesn't need to be as high.

If you are really on a budget, I'd suggest a wooden mast and a wire vertical with elevated radials.  You need fewer radials if the radials are elevated.  One cheap way of changing the  resonant frequency is to either change the length of the radiator or to change the wire--put a pulley at the top of the mast. 

It is possible to work DX through a brick house with aluminum siding--I've worked Japan with 5 watts on 20 meters with my 20' flagpole.  If you are just getting started, it is better to focus on what you can work than what you can't--even with decades of experience, most hams need a lot of time to get a station performing well on all bands and all modes.

Zack Lau W1VT
« Last Edit: August 30, 2013, 08:48:41 AM by W1VT » Logged
K1THP
Member

Posts: 10




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« Reply #10 on: September 08, 2013, 05:27:29 PM »

If you can't put up a tower and beam try an Off Center Fed Dipole (AKA Windom). After many years of antenna experimentation I put up a full size OCD (135 Feet) at forty feet of height. This has been the best (for the bucks) antenna I have used at this QTH ... and it covers all bands! I also like and have used the Butternut Vertical since 1979. It is ground mounted with 12 thirty three foot radials that were pinned to the lawn and are now buried under several inches of composted grass clippings. The trick to this antenna is to keep it as far as possible from the house and other structures. Also, the Butternut survives a lot better with three guys that go from about 10 feet up to ground. I used Dacron cord from a hamfest vendor and tent pegs to do the guying.
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KA0HVE
Member

Posts: 117




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« Reply #11 on: September 15, 2013, 04:30:07 PM »

Using CW on 20 meters I just contacted a guy 950 miles away while I was transmitting with 1 watt.  Maybe I had better try out this little antenna some more before I go switching to something else.  Grin
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W1JKA
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Posts: 1778




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« Reply #12 on: September 15, 2013, 05:38:10 PM »

Re: KA0HVE

   What kind of little antenna did you put up?
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KA0HVE
Member

Posts: 117




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« Reply #13 on: September 15, 2013, 06:53:03 PM »

It's a W3EDP.  It has an 84' radiator and a 17' counterpoise hooked to my tuner.  The radiator is inverted L with highest point about 15' in the air.  I made it with part of a 100' piece of light weight speaker wire from Target. I used about $6 worth of the $11 coil of wire.  Smiley

I call it little because I could keep the wire in a pipe tobacco tin if I used it portable.

I just made another contact near Boise, ID.  QRZ said 1157.9 miles.  That was on 1 watt also.  The guy gave me a 559.

Over 1,000 miles with 1 watt was my next goal and I just completed it.   Grin

I love this QRP stuff.  I'm hooked!
« Last Edit: September 15, 2013, 07:03:06 PM by KA0HVE » Logged
W1JKA
Member

Posts: 1778




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« Reply #14 on: September 16, 2013, 03:05:53 AM »

Re: KA0HVE

  Great show with your antenna, it appears that OptiBeam just lost another sale and your results will only get better as your knowledge of propagation/grey lines increase.
« Last Edit: September 16, 2013, 03:15:17 AM by W1JKA » Logged
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