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[Articles Home]  [Add Article]  

Angle of Radiation - What is it?

Bill (K2WH) on March 9, 2004
View comments about this article!


One of the more important performance characteristics of an antenna system is its angle of radiation. Angle of radiation is not built into an antenna, you the amateur make that happen by the placing your antenna at the proper height. Therefore, I thought of this mental exercise of what radiation angle really means.

Angle of radiation when referring to antennas, is simply the take off angle of the RF field when launched from your antenna in relation to the ground (earth). That is, if your dipole antenna is low to the ground (< 1/2 wavelength), in relation to its frequency of operation, the angle of radiation from the dipole will be at or close to 90 degrees - straight up and the dipole will behave as an omni-directional antenna. The higher you place your antenna above ground, the lower the radiation angle. A height is finally reached (depending on installation), when the “Take off” angle (Magic Height) is in the 20 degree range or lower. A radiation angle of 20 degrees or lower is an ideal angle for working long range DX. This means, the major lobe of your RF energy is radiated at an angle of 20 degrees in relation to the horizon. The horizon being zero.

The “Magic” antenna height is generally achieved when your antenna is 1/2 wavelength above ground assuming a perfectly conducting ground (earth). There are many variations in ground conductivity ranging from something very similar to an insulator (sand and broken beer bottles) to salt water which is the best with everything else in between. Different ground types make the 1/2 wavelength rule different depending on where you live. If you live by the ocean, you are very lucky indeed. If you live in the mountains, you're not so lucky.

How do you know when you are about 1/2 wavelength above your ground? Simple math. Take 468 and divide it by the frequency you intend to operate. Again assuming perfect ground, this number just happens to be the same number you would use to cut a resonant dipole to length.

This begs the question, “Why should I bother to achieve a low angle of radiation”. If you want the strongest signal possible at a distant point, a low angle of radiation is essential.

For instance:

You want to put up a dipole antenna for 40 meters, frequency is 7.250 MHz. Therefore, 468 / 7.250 = 64.55 feet. This height will vary depending on your type of ground, but generally it is the approximate height you would want your feed point to be located for best DX capability. It will give you a low angle of radiation which is very good for working DX. Believe it or not, some angles of radiation are better than others for working different parts of the planet. That's another story in itself.

Visualize this:

Suppose I have a rubber ball in my hand. I throw it as straight down as possible at the floor. It will rebound and probably hit the ceiling directly above the point where it hit the floor. It will then hit the floor again and then rebound to hit the ceiling again close to the same spot again, all the while losing energy in the bouncing process from floor to ceiling.

This will continue until all the energy is used up. Notice the ball did not travel very far from the origin point.

The floor in this example, can be looked upon as your ground, the ceiling the reflecting medium or, the ionosphere. This is how your signal travels from a low dipole delivering a very strong local signal because most of the RF energy is expended locally. The signal (ball) goes straight up and straight down for the most part. The result is many hops losing energy as it moves forward very little.

Now if I throw the same ball at the floor so it rebounds at about a 20 degree angle from the floor, the ball travels much further on the first bounce before it hits the ceiling. On the second bounce, it has moved quite far from its origin point. This is how your signal travels from a dipole when it is 1/2 wavelength above perfect ground. It travels much further between hops and loses much less energy before arriving at its final destination - the DX station. Remember however, your signal has now become directional so don't point the ends of your high dipole to the part of the world you want to talk to. No free lunch here.

Now, with a 20 degree take off angle, your local signal is much less powerful because most of the RF energy is passing overhead and not being reflected straight down. Local stations hear your ground wave signal which is good for about 50 miles and not very strong beyond that. You receive mediocre signal reports from your 1/2 wavelength high dipole vs your low dipole. This is why a vertical is considered a superior antenna for DX vs a dipole because they have an inherent low angle of radiation when installed properly and are not directional but usually require lots of radials to work properly.

Now if you are a DX hunter, a low angle of radiation is a good thing. A low angle of radiation equals a good DX antenna but if you want a strong signal locally, then a low dipole with a high angle of radiation is better.

As we can see, to really do your best with the DX and still have a good strong signal locally, you really need 2 antennas that you can switch between. You need one antenna with a high angle of radiation and one antenna with a low angle of radiation. Quite possibly, a low dipole and a good vertical.

I hope this helps readers out there to grasp the meaning of “Angle of Radiation”.

K2WH

Member Comments:
This article has expired. No more comments may be added.
 
Angle of Radiation - What is it?  
by VE4HQ on March 9, 2004 Mail this to a friend!
Excellent article-lets hear more of the same.
--Anyone have any results on the "DX SPECIAL" from the ARRL hand book?
 
RE: Angle of Radiation - What is it?  
by G7HEU on March 9, 2004 Mail this to a friend!
K2WH

Nice article, thanks for that.

I used to have two antennas - a 1/2 G5RV and a 1/4 wave vertical for 20Mtrs. The difference was exactly as described.

Then the planning police got involved. My 1/4 wave was legally classed as an unauthorised building and had to come down.

I am now mostly experimenting with NVIS on 40Mtrs!

Steve
M0HEU / G7HEU.
 
RE: Angle of Radiation - What is it?  
by KA4KOE on March 9, 2004 Mail this to a friend!
I wonder if a fan dipole has any special takeoff angles?
 
RE: Angle of Radiation - What is it?  
by AG4RQ on March 9, 2004 Mail this to a friend!
Only if its a rotating fan dipole ;-)
 
RE: Angle of Radiation - What is it?  
by URBANGORILLA on March 9, 2004 Mail this to a friend!
The information in this article is very useful, but what does it have to do with CW?

U.G.
 
Angle of Radiation - What is it?  
by KB0GU on March 9, 2004 Mail this to a friend!
Good article Bill, uh... is your last name Orr? 73's
 
RE: Angle of Radiation - What is it?  
by W3NRL on March 9, 2004 Mail this to a friend!
Thank you. This is very good, there is always time to learn.
Again thank you for the education
w3nrl
 
Angle of Radiation - What is it?  
by K3NG on March 9, 2004 Mail this to a friend!
You are one smart electrical dude !
 
Angle of Radiation - What is it?  
by KAPV9947 on March 9, 2004 Mail this to a friend!
Very Good Topic. Very well put together and stated. Thanks
 
RE: Angle of Radiation - What is it?  
by KC8VWM on March 9, 2004 Mail this to a friend!
Very good article. However, I am not in a position to put my antenna at it's optimum height to gain the proper angle of radiation.

I do however have both a vertical and a 120 foot "Inverted -Zigzag" whatcha ma call it long wire antenna with a 4:1 Balun in my attic. These antennas are only up around 30 feet. The vertical is at a slight angle because of its overall height and cramped attic design.

I hear that placing a vertical HF antenna at a slight angle to the ground helps with NVIS patterns. At least this is what ships at sea do with their HF antennas to improve their reflected skywave propagation.

Great information!

73

Charles - KC8VWM
 
RE: Angle of Radiation - What is it?  
by K9PO on March 10, 2004 Mail this to a friend!
FYI the free space half wave length formula that you should be using is 492/F(MHz) not 468/F(MHz). This will give you the physical halfwave length.

The 468 number is derived from .95*492 which is the amount you shorten the antenna when it is a wire antenna to get it to its electrical halfwave length. Other than than minor nit good article.
 
RE: Angle of Radiation - What is it?  
by W6TH on March 10, 2004 Mail this to a friend!
I will shorten the wording and put it the way a engineer would write it.

The antenna wave angle for a horizontal antenna is "A GEOMETRICAL FUNCTION OF ANTENNA HEIGHT ABOVE GROUND".

For a vertical antenna the wave angle is determined by the height of vertical, the image. The take off angle will be .35 wavelength from the base of the vertical.

A 1/4=32 degs. 3/8=20 degs, 1/2=16 degs, 5/8=11 degs.

For dx work, go as high as you can afford for a horizontal.

For dx with a vertical, go for the 5/8 wavelength and get a good 3db plus gain.

73 gang, W6TH.

.:

 
RE: Angle of Radiation - What is it?  
by KA4KOE on March 10, 2004 Mail this to a friend!
WH:

You get to say "they aren't dudes" again. I'm writing No. 9 now. Its on Lee Deforest.
 
RE: Angle of Radiation - What is it?  
by K4JSR on March 10, 2004 Mail this to a friend!
WH is a DUDE! (A LIVE ONE)
 
RE: Angle of Radiation - What is it?  
by HB9PJT on March 10, 2004 Mail this to a friend!
I do not absolutly agree. The ARRL antenna handook shows that the angle for DX is between 5 ans 15. So why not put the antenna higher to get a lower angle (at least for the higher bands)?

The quality of the ground does not matter much for horizontal polarisation.
 
RE: Angle of Radiation - What is it?  
by N6AJR on March 10, 2004 Mail this to a friend!
Arrl has a video tape on something exactly that covers this. It is on the fron of the one with the spark gap transmitter.

We got a copy for my local club and I was so impressed I bought my own copy.

This fellow ( engineer type) had this little square plate with a 3 or 4 ghz oscilator in it. He procedes to install a bout 30 or 40 different antennas on this oscilaroe and has a probe with a small 2 ele beam on it fo a pickup.
the rx antenna feeds a speaker, so you can "see" ( actually hear) the signal strength as he moves the pick up wand around the fixed antenna, it shows angle of radiation, polarity issues, gain.. etc a really neat video.. I think it is tape # 12.. but not sure. take $12 an check out your own.. 73 tom N6AJR
 
RE: Angle of Radiation - What is it?  
by KC8ZBV on March 10, 2004 Mail this to a friend!
It is sort of like the angle of the dangle being inversely proportional to the heat of the meat.
 
Angle of Radiation - What is it?  
by W5EN on March 10, 2004 Mail this to a friend!
I enjoyed reading your work, and your nice presentation of a complex topic. Your work was sure much more of a joy to read than my 4000 level engineering class on electromagnetics. My goodness I have nightmares about the solution to the differential equation dealing with E x H fields. LOL
How about an aritcle about not worshiping the god of swr? It has always been a thorn in myside how antenna companies brag about low swr accross the band. What new commers to our hobby may not know or realize is that a 50 ohm resistor also has a "broad swr". I think a discussion of radiation resistance would dove tail well with the take off angle article. Again GREAT JOB!

73
Steve W5EN
 
RE: Angle of Radiation - What is it?  
by KC8VWM on March 10, 2004 Mail this to a friend!
Thats a good point W5EN. Although antenna design is important and they say the lowest SWR is also important, I find that my radio actually performs with a better signal when the SWR is at 1:5 as opposed to 1:1.

Has any one else experience this phenomenon?

73

Charles - KC8VWM
 
RE: Angle of Radiation - What is it?  
by N2MG on March 10, 2004 Mail this to a friend!
HB9PJT wrote:
> I do not absolutly agree. The ARRL antenna handook shows that the angle for DX is between
> 5 ans 15. So why not put the antenna higher to get a lower angle (at least for the higher bands)?

This is a valid issue - while a half-wave above ground is often used as a rule-of-thumb (it does provide reasonable performance and "loads" or matches well), often a full wavelength or more is needed for maximum signal. The actual optimum height (in wavelengths) of an antenna at any given time depends on the sunspots, time of day, how far away the DX is, etc. For example, when 10 meters first opens in the morning to Europe from the east coast, a 2- or 3-wavelengths high antenna does quite well, while lower antennas hear nothing. As the band opens, lower antennas begin to "play" and slowly become the better performers.

So, if asked, I'd recommend that a full wavelength be the goal.

However, don't let all that stop you... put the antenna up and work stuff! I've had great DX success with 1/2-wave high (or lower!) 40m and 80m horizontal antennas...

Mike N2MG
 
the god of swr  
by N2MG on March 10, 2004 Mail this to a friend!
W5EN wrote:
<<
How about an aritcle about not worshiping the god of swr? It has always been a thorn in myside how antenna companies brag about low swr accross the band. What new commers to our hobby may not know or realize is that a 50 ohm resistor also has a "broad swr".
>>

Even lossy coax can make a really poorly matched antenna look like it has a good match if SWR is measured at the transmitter end.

High SWR cannot be ignored as it can cause damage to components (solid state rigs cut back in its presence; many modern amps will "trip" on it). However, it is just one of many parameters that needs to be addressed in a good antenna design/installation.

Mike N2MG
 
Angle of Radiation - What is it?  
by K6OHH on March 10, 2004 Mail this to a friend!
A very well written treatise on the subject.
Are you a teacher??
If not...consider elmering.
We need more material written in this manner for basic understanding.
Rob K6OHH
 
RE: Angle of Radiation - What is it?  
by K3ESE on March 10, 2004 Mail this to a friend!
Great stuff! Mega kudos!

...and I'll get to say they are dudes. wonder if I'll beat WH again, this time...
 
RE: Angle of Radiation - What is it?  
by N2OBY on March 10, 2004 Mail this to a friend!
I'll see if I can get John N2XE to write something up about the "myths" of SWR. He has recently been giving The QSY Society a series of short, easily understood technical presentations, and two back-to-back sessions covered that very topic.

-Ken N2OBY
 
Angle of Radiation - What is it?  
by KA0UK on March 10, 2004 Mail this to a friend!
Very well done indeed. This would be a good model for a book covering general ham radio topics designed for many of us but directed toward the new ham. I wish I had had such a book. Perhaps the ARRL would sponsor such an effort. Something more complete than current offerings but much easier to read than the ARRL Handbook. Hams with your ability to simplify complex topics without over generalization could be asked to contribute. We need more hams and this is one way to get them interested.
David KA0UK
 
RE: Angle of Radiation - What is it?  
by K3AN on March 10, 2004 Mail this to a friend!
An additional clarification. The angle of radiation is the angle at which MAXIMUM radiation occurs. There will be at least some radiation at all angles, but low antennas will have very little radiation at the low angles that favor DX communication.
 
Angle of Radiation - What is it?  
by VE3XYD on March 10, 2004 Mail this to a friend!
that explains why I do great DX work with my vertical, but I cannot chat with a friend of mine that is just 30 miles away from me. My vertical is 40 feet above the ground on a tower. I guess its time toput up a dipole for local chatting...

great article
73


 
RE: Angle of Radiation - What is it?  
by KC8VWM on March 10, 2004 Mail this to a friend!

>>>I'll see if I can get John N2XE to write something up about the "myths" of SWR. He has recently been giving The QSY Society a series of short, easily understood technical presentations, and two back-to-back sessions covered that very topic.

-Ken N2OBY <<<

Hey Ken, what a great idea!

I would especially be interested in this topic. Thanks!

Charles - KC8VWM
 
RE: Angle of Radiation - What is it?  
by K4JSR on March 10, 2004 Mail this to a friend!
In my day antenna radiation patterns were only to be
considered if the antenna was in "free space".
NASA and the cost of towers has shown that space ain't free! It ain't even reasonable! The 1/2 wave-
length above ground is a far more economically
feasible compromise. However, the variable of ground
conductivity beneath a specific antenna can cause
serious headaches for modelling purposes. There will
always be some "fudge factor" because of that fact.
The great VSWR will be with us until Hades freezes
over. As long as people feed antennas with coaxial
cables there will be concerns over return loss.
Granted most people obsess over VSWR. As long as the
return loss, a measurement of how far down in dB the
returned power is, is low enough, as measured at the
feed point of the load (antenna) to keep your
transmitter's PA happy, and you are using a good
quality, low loss cable, don't worry about it.
At that point there is not a whole lot that you can do that will be noticed by anyone on the receiving end. If you use a good 450 Ohm or 600 Ohm twin lead
to feed your antenna you don't worry about VSWR
very much. Your feedline losses will be minimal,
the antenna will radiate, and if you have a decent
Transmatch your final PA will be happy.
However, if minutia excites you, or if you are just
plain obsessive, that is just as valid a reason in
this part of the hobby to get your panties in a wad.
That *IS* what we are about. Study it. Play with it.
Learn from it. Most important--*ENJOY IT*.
There is nothing wrong with re-inventing the wheel as
a hobby. That is what modelers and experimenters
do!
Lloyd, ESE, You beat WH as have I. I have even let
the cat out of the bag that WH is a DUDE (In denial)!
;-D Now everybody go build an antenna and worry your
neighbors! They already think that we hams are very
strange, anyway! Let 'em worry! ;-D
73, Cal K4JSR
PS. Wouldn't it be really cool if you could sprinkle
powdered iron around your latest antenna and check
its H field like you check a magnet's field? :-)
 
RE: Angle of Radiation - What is it?  
by K2WH on March 10, 2004 Mail this to a friend!
I am not a "Dude". I may be a "Dud" from time to time but never, ever a "Dude".

K2WH
 
RE: Angle of Radiation - What is it?  
by KA4KOE on March 10, 2004 Mail this to a friend!
Sure you are. The first part of recovery is admitting it.
 
RE: Angle of Radiation - What is it?  
by K1OU on March 10, 2004 Mail this to a friend!
After evaluating my performance on forty for sweepstakes the last couple of years, it was obvious that something was lacking. So, I did the unthinkable and actually took some advice and put a dipole up fifteen feet. Contrasting logs, a lot of the real close in stuff where I was lacking previously really filled in. This antenna rocked compared to the delta loop at sixty feet. In A/B tests within 300 miles, the cloudwarmer was generally 5-10db louder, of course unscientific. If ya wanna kick butt up for your local coffee klatch, a dipole anywhere from a quarter wave to a half wave in the air will do great.
 
RE: Angle of Radiation - What is it?  
by K2WH on March 10, 2004 Mail this to a friend!
For clarity, I used a 20 degree radiation angle as an average number. In my experience, with different ground types with horizontal antennas and vertical, 20 degrees is about right for most antenna installations over average ground.

A lower angle of radiation is better to a point and lower the 20 degrees starts to become a goal that is not obtainable with certain ground types.

Angles below 5 degrees start to become a problem due to ground clutter absorbtion, hills, buildings etc. (except over sea water of course).

K2WH
 
Angle of Radiation - What is it?  
by KB4CDC on March 11, 2004 Mail this to a friend!
Still.... How to calculate the angle of radiation(which is a real number)? WHAT IS IT? All we have wrote here is about wavelenght and antenna hights.
 
Angle of Radiation - What is it?  
by KC7ATO on March 11, 2004 Mail this to a friend!
All users of highly charged rotating fan dipoles should check their equipment for uncontrolled spurious emissions.
 
RE: Angle of Radiation - What is it?  
by KC0JBJ on March 11, 2004 Mail this to a friend!
Ok, you mentioned 1/4 wave verticals with good ground planes (radials) and 1/2 wave horizontal center-fed dipoles mounted 1/2 or more wavelengths above ground as having low angles of radiation. What about ground-mounted 1/2 wave VERTICAL center-fed dipoles or off-center-fed verticals like the Hy-Gain DX-77 "no ground-plane" antennas? What kind of angle of radiation do they have? I am assuming it is also very low, right?

Also, if you have a 20 meter horizontal beam mounted on a crank-up tower, does that mean you can change it from low-angle DX to high angle NVIS by cranking the tower back down below 35 ft.? Will it lose directionality as well?
 
RE: Angle of Radiation - What is it?  
by N6AJR on March 11, 2004 Mail this to a friend!
yes.. old timers frequently used to lower their crank ups to hit folks close in..
 
RE: Angle of Radiation - What is it?  
by K2WH on March 11, 2004 Mail this to a friend!
Yes, the angle of radiation applies to beams as well. Remember, a beam is simply a dipole with a reflector and directors to direct RF in the proper direction which subjects it to dipole height requirements.

A low beam (lower than 1/2 wave) will have a high angle of radiation. That is why you must have a beam at the proper height for maximum effectiveness. Otherwise, you beam pattern will not be directed down at the horizon.

K2WH
 
RE: Angle of Radiation - What is it?  
by KA4KOE on March 11, 2004 Mail this to a friend!
WH:

Release is nearly at hand. DED 9 is in the bin.

P
 
RE: Angle of Radiation - What is it?  
by K2WH on March 11, 2004 Mail this to a friend!
Oh forgot. If you lower your beam, you will start to "Fill in" the area overhead with RF just as you would with a low dipole. While i'm not an expert on this matter, this would seem to indicate a loss of directionality.

K2WH
 
RE: Angle of Radiation - What is it?  
by KC8VWM on March 11, 2004 Mail this to a friend!


>>>>With the exception of the very lowest dipoles, most dipoles will gain an extra 2 db or so of vertical gain if you allow the center to droop a few feet. Allowing the center to droop means that the end supports don't have to be as sturdy, which makes installing a good NVIS dipole that much easier.<<<<


For those interested, here's my favorite article explaining NVIS (Near Vertical Incident Skywave) propogation in good clarity -


http://www.qsl.net/wb5ude/nvis/

73

Charles - KC8VWM
 
Angle of Radiation - What is it?  
by N5RMQ on March 11, 2004 Mail this to a friend!
Very informative article. Great illustration on take off angle. We need more of this and less grousing. Thanks for a great article.
 
Angle of Radiation - What is it?  
by N5RMQ on March 11, 2004 Mail this to a friend!
So I thought this would be a great way to explain to the xyl how I am able to talk to all those different countries. After doing a little demo she shook her head and said O.K. I get it. A few days later, her and a friend were talking and The friend asked "what does your husband do in that little room with all those radios? She replied "he talks to alot of countries by bouncing a racquetball off the ceiling" I tried.
 
Angle of Radiation - What is it?  
by AD5CA on March 11, 2004 Mail this to a friend!
The angle of radiation = sin-1 (0.25/h) where h = the antenna height above ground in wavelengths.
(The sin-1 is inverse sine but I couldn't get it to type)
I believe an antenna at 1 wavelenth is best for most reliable dx communication.
Great topic, and I agree that for a horizontally polarized antenna the quality of the ground is not nearly as critical as with a vertical.
Thanks for the post.
Mark AD5CA
 
RE: Angle of Radiation - What is it?  
by KY6R on March 11, 2004 Mail this to a friend!
For a while I used a low hanging (30') 135' horizontally polarized ladder line fed doublet. After working 225 DXCC entities I hit the wall.

I bought the full version of EZNec and noticed why - at all frequencies lower than 20M it was a cloud burner - but a couple of years ago (at the second peak of this current cycle) it still worked quite well.

I looked at the antenna in EZNec and also visited the best antenna web site - http://www.cebik.com - and also bought and read the ARRL Antenna Book and ON4UN's Low Band DX-ing antenna book, and realized that I needed a lower TO angle.

At the same time - over a year ago, I noticed that with every solar storm, my horizontal antenna seemed more like a noise generator.

Enter the "low hatted vertical dipole". It has a 20 degree TO angle and has a very good S/N ratio - which means, although it has unity (no) gain, you actually hear more because you hear the signal with less noise.

Even better (as far as elegant / simple) antennas is concerned is the half square - its a pair of phased verticals with low TO angle, high angle noise rejection, and pretty much requires the same supports that a half wave dipole would.

I have experimented with loops, Moxon rectangles and yagis - but for simplicity sake - the short hatted vertical dipole (unidirectional and no gain) or the half square (bi-directional and 3 db gain) fit my needs best.

 
RE: Angle of Radiation - What is it?  
by K2WH on March 12, 2004 Mail this to a friend!
For those wondering, TO = "Take Off"
 
Magic height  
by WB2WIK on March 12, 2004 Mail this to a friend!
Nice article and good comments.

It's good that even when band condx are crappy, at least we can write about it!

WB2WIK/6
 
Angle of Radiation - What is it?  
by WA2JJH on March 15, 2004 Mail this to a friend!
Excellent and an easy read. I cannot belive you are the same dude that that goes.......!"THEY WERE NOT DUDES" in Philips KA4KOE'S dead electrical dude series!


PHILIP will be expecting your usual contribution.

Nice to see a brain to go with the non sequeters!

I always thought a a 1/2 wave above ground was an absolute minimum. A full wave length is better. However many city slicker hams like me have limited roof rights.

Would love to have a 20M inverted V 1/2 wave length above my roof. I like inverted V's because of thier instinsic 50 ohm impedence, and large bandwidth when used with thick guage wire.

A 20M inverted V will work OK on 10 and 40M with a tuner.
An old ham chum only had a 15M inverted V. The antenna was about a full wave length above ground.

He got W.A.S in 2 months! DXCC in 8 months.
CW of course(oh, I should not have said that)

73 MIKE a dude


I think inverted V's are known by a subcult as a FAN-DIPOLES (HI_HI)!

However I am stuck with verticals for now.
 
Angle of Radiation - What is it?  
by WA2JJH on March 15, 2004 Mail this to a friend!
Excellent and an easy read. I cannot belive you are the same dude that that goes.......!"THEY WERE NOT DUDES" in Philips KA4KOE'S dead electrical dude series!


PHILIP will be expecting your usual contribution.

Nice to see a brain to go with the non sequeters!

I always thought a a 1/2 wave above ground was an absolute minimum. A full wave length is better. However many city slicker hams like me have limited roof rights.

Would love to have a 20M inverted V 1/2 wave length above my roof. I like inverted V's because of thier instinsic 50 ohm impedence, and large bandwidth when used with thick guage wire.

A 20M inverted V will work OK on 10 and 40M with a tuner.
An old ham chum only had a 15M inverted V. The antenna was about a full wave length above ground.

He got W.A.S in 2 months! DXCC in 8 months.
CW of course(oh, I should not have said that)

73 MIKE a dude


I think inverted V's are known by a subcult as a FAN-DIPOLES (HI_HI)!

However I am stuck with verticals for now.
 
Angle of Radiation - What is it?  
by KN4LF on March 16, 2004 Mail this to a friend!
One thing to remember is that an antenna transmits "some" RF at all takeoff angles say between 5 and 90 deg. If a 1/4 wave vertical has a take off angle of 20 deg., that is the angle of "maximum" radiation of current. It's not a concentrated spotlight or lighthouse type of effect.

73,
Thomas Giella, KN4LF
Plant City, FL, USA
 
Angle of Radiation - What is it?  
by KE4ZHN on March 18, 2004 Mail this to a friend!
Good article Bill. You did a nice job explaining the theory behind it and how different antennas produce different patterns. Very enjoyable thread.
 
RE: Angle of Radiation - What is it?  
by N4KMA on March 19, 2004 Mail this to a friend!
Excellent article. I enjoyed reading it and learning from it. Thank you!
 
Angle of Radiation - What is it?  
by EI2GEB on March 21, 2004 Mail this to a friend!
Thanks indeed Bill for making the subject very simple to understand but yet so effective, I only wish I had some of these topics explained so well whenever I was undertaking the the course for the theory exam last autumn here in Ireland, KEEP UP THE GOOD WORK, 73s from the emerald isle EI2GEB
 
RE: Angle of Radiation - What is it?  
by KA4KOE on March 22, 2004 Mail this to a friend!
Angle of incidence = angle of reflection.

Bounce a billiard ball off the side of a pool table and it will demonstrate this concept. Good article, by the way.

To reiterate Mike, we all look forward to your concise one-liner when DEDs 9 and 10 (queued up) hit the front page.

:)

PHILIP
 
RE: Angle of Radiation - What is it?  
by K7JBQ on April 21, 2004 Mail this to a friend!
Indeed a great article, but it begs a doubtless dumb question:

When calculating height above ground for a horizontal antenna, what exactly is "ground?"

To wit, if a dipole is 6' above a reinforced concrete balcony, which is itself 25' above the street, is the antenna height 6', 31', or something in between, as far as take-off angle goes?

I have searched the literature to no avail, and I have to think this is of concern to many operators.

73,
Bill
 
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