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The Myth Surrounding Antenna Take Off Angles

TheBlaster

Well-Known Member
Jun 29, 2020
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I consider it often. However it is quite difficult for DXers because on any given day there may be better or worse conditions and paths for any given angles. The ideal is having a nice wide spread of angles up to around 30 degrees with the best antenna you can use on the day.

It is difficult to know the angle of radiation for any given DX contact on any given band with certainty. The maxim, if any..... is to use an antenna with the lowest angle of radiation that you own. This will produce most likely chance of a good DX contacts at all signal levels and distances.

What we know is that as frequency rises the DX angles at play generally become lower. We also know lower incident angles make longer hops and that lower angles tend to have greater attenuation scraping along in the F2 layer per hop... but probably less getting through the D layer en route. So it evens up a bit.

Always put the best DX antenna you can safely put up... that is the rule of thumb. Most important is to be calling or listening with an antenna. Models don't make DX contacts.

Also don't stress about it too much as there can be some head scratching surprises along the way when the conditions perk up it is amazing what can happen with the basics. Go into it as much as your own enjoyment allows.(y)
 
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nfsus

Yeah its turned off, touch it
May 9, 2011
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It's an old thread, but I've noticed that height can make or break you. I've set up a crank up 40ft pole. I can change the recieve and tx signal to the good or to the worse by not only raising the antenna but as also by lowering it. Imaginary heights for wavelength are just ideas and dreams. There is an ebb and flow to the currents in the ground no matter what the nec says about modeling over ground types. Using the same local guys (super scientific) you can adjust height to maximize your signal. It's not just higher higher higher for most of us. Now once you get way up there, yeah that's a whole different ballpark, but adjusting height to affect the radiation pattern is where it's at for most of us height challenged poor folks but instead we ignore that and buy gadgets or new antennas that dont preform any better because we put them right back where the old one was at.
 

Flatop

Active Member
Apr 12, 2019
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It's an old thread, but I've noticed that height can make or break you. I've set up a crank up 40ft pole. I can change the recieve and tx signal to the good or to the worse by not only raising the antenna but as also by lowering it. Imaginary heights for wavelength are just ideas and dreams. There is an ebb and flow to the currents in the ground no matter what the nec says about modeling over ground types. Using the same local guys (super scientific) you can adjust height to maximize your signal. It's not just higher higher higher for most of us. Now once you get way up there, yeah that's a whole different ballpark, but adjusting height to affect the radiation pattern is where it's at for most of us height challenged poor folks but instead we ignore that and buy gadgets or new antennas that dont preform any better because we put them right back where the old one was at.
Yes, too high can have a detrimental affect.
 
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Riverman

Old Member
Nov 12, 2013
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Using horizontal antennas (at low heights of 10-18'), I have never made it into Europe.
Using vertical antennas only 4-5' above the ground, I often get there. Even with just a single wire radial.

If I'm plagued by deep nulls, I'm not sure of their direction as I have contacts to the north, west and south as well. Perhaps North by Northwest. (n) Wasn't Jimmy Stewart in that? Or was it Cary Grant? :D
 

Crawdad

Down in the mud invasive species
Nov 11, 2016
873
1,816
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Using horizontal antennas (at low heights of 10-18'), I have never made it into Europe.
Using vertical antennas only 4-5' above the ground, I often get there. Even with just a single wire radial.

One would have to think that results must vary with different locational situations (terrain, mean elevation, ground conductivity, etc.) since I have made western Europe on a flattop and an inverted Vee @ 18 or so feet with 30w PEP. Haven't used/had a vertical since the 80s so I can't really compare the two. If I were to believe all the myths about horizontal dipoles I might not have an antenna up at all.

73
 
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Riverman

Old Member
Nov 12, 2013
2,682
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If I were to believe all the myths about horizontal dipoles I might not have an antenna up at all.
73

:ROFLMAO:

And you are right about terrain, mean elevation, ground conductivity and all that stuff. Oh, and conditions. (y)

Mine might be the only location where my current antenna performs decently. :)
 
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The DB

Sr. Member
Aug 14, 2011
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1,502
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St. Louis, MO
It's an old thread, but I've noticed that height can make or break you. I've set up a crank up 40ft pole. I can change the recieve and tx signal to the good or to the worse by not only raising the antenna but as also by lowering it. Imaginary heights for wavelength are just ideas and dreams. There is an ebb and flow to the currents in the ground no matter what the nec says about modeling over ground types. Using the same local guys (super scientific) you can adjust height to maximize your signal. It's not just higher higher higher for most of us. Now once you get way up there, yeah that's a whole different ballpark, but adjusting height to affect the radiation pattern is where it's at for most of us height challenged poor folks but instead we ignore that and buy gadgets or new antennas that dont preform any better because we put them right back where the old one was at.

There are ham radio contesting stations that have massive towers with the several of the same antenna at multiple places on said towers. They not only switch between antennas, but also run some or all of the antennas in phase, which all affects the angles that said antennas are sensitive to, all to get the best results.

Height is might, a common saying when it comes to antennas, is true but only to a point.

When it comes to modeling and local performance, most people use models that have nothing to do with local performance to try and say an antenna will perform better when it comes to local contacts. They believe that just because an antenna has a lower angle of radiation that that means its local contacts will automagically be better. This is in error as most of the antennas of the radio stations they are trying to contact will be far below this angle, and in some cases, literally below the lowest horizon of the plot they are using. The truth is, this type of plot is pointless in said circumstances.

In reality, freespace is better for determining how well local performance for an antenna is. If the antenna is low to the ground, whatever antenna has the best 0 degree gain in freespace will tend to perform the best, and as you gain height, you need an antenna that will actually perform the best at a slight downward angle. The more height you gain the bigger this angle becomes. The reason that height needs said downward angle is that the earth curves away from where the antenna is radiating. There is only one antenna design out there that I am aware of where you can get a downward angle, the Signa-4/Vector-4k design, and you have to be willing to play with its dimensions to achieve it. Several people on this forum in the past have confirmed this effect, and modeling backs it up as well. The thing is, you will never see this effect on the typical gain plot that people tend to look at, and in many cases the better local setup will actually have worse gain on said plots, so using them for optimizing local setups is literally shooting yourself in the foot.

Unfortunately, even this makes assumptions, such as the earth being not only round, but fairly smooth, which in many places, including here in the middle of the Great Planes of the US where I live, it just isn't, which often means to get contacts in a certain direction you need to at least clear the height of whatever obstacles are in that direction, be it hill or mountain, some buildings based on their design, ect.

There are a lot of things that are going around the radio hobby that are taken as absolute fact. The thing is many of them while having an element of truth, are only true to a point, or in certain circumstances. Its not just the angle of radiation where these types of beliefs exist, you may have seen me occasionally refer to what I call the "coaxification of antenna knowledge", which is simply a theory I have come up with about ideas in the hobby that are taken as absolute fact by most but aren't actually true, and have come about because of the limits of using coax as a feed line.


The DB
 

wavrider

W9WDX Amateur Radio Club Member
Jun 2, 2009
3,409
1,282
173
Angles vary,,its the nulls you need to worry about.

When the angle of radiation is understood about the antenna you install. Then you can control the lobes of the radiation pattern.

Yagi vs dipole. Of course the yagi has more gain but in real world testing switching back and forth between a mosleypro67B and a dipole the DX station barely seen any difference in the two antennas. Tested multiple times on different days.
Local talking, inside the USA Canada, S America the yagi edged out the dipole.
On long haul DX they were about even.

Just my real world results, the ionosphere and propagation on long haul DX makes a big difference on signal.

Now go to a full wave loop or Delta loop and these type antennas are about the same as a three element yagi in gain. work well, WHEN installed correctly. Key word is installed.

That is why most see the yagi outperform the wires due to being able to use rotor to AIM yagi in direction desired.

Next is the height above ground VS angle of radiation.
I have several towers all with hazers , pulleys ,,etc etc.
I have experimented with yagis and dipoles, multi band and mono band.

I have come to conclusion a 1/2 wl dipole installed 1/2 wl AGL oriented in the direction of the world you want to send your main lobe in works very well. propagation taken into consideration.
this is for 20 meters and up in freq.

40 meters and down I use ground mounted verticals, I do not have tall enough towers to get 1/2 wl in height for 7 MHz or lower in freq, but the vertical allows me to work dx good, rather noisy on rx.
 
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