dipole TOA and beams ?????

[BOOTY MONSTER]

be for warned ..... im bored and ive been thinking again .......

it seems a vertical dipole and a 1/4 wgp essentially perform the same but just have a different ground element(s) configuration . and we know that 1/4 wgp's have a higher toa than 1/2 wgp's and that 5/8 and .64 wgp's are even lower . so a dipole has a radiation pattern similar to a heart (if you will) . beams are just a dipole with a reflector with differing numbers of directors spaced and sized accordingly .

running that beam vertically does it have a TOA still similar to the 1/4wgp/dipole or is the TOA affected by the reflector and driven elements ? im thinking it doesn't because if it did running it horizontal wouldn't it put its maxim tx and rx diagonally across the beam favoring the hot/radiating element ? wouldn't the pattern be similar to laying that heart shape down sideways ? then to get maxim tx and rx you don't actually point the beams beam directly (on axis) with the desired direction of communication , but (kinda/sorta) across opposing ends of the driven and reflecting elements ?

am i wrong from the start about the toa of a dipole ? does it radiate with a flat toa like a doughnut with no stronger lobes coming off the top giving it a heart shaped radiation pattern ?

im obviously miss understanding or don't understand something here so take me to school guys .

 

[GnG8d]

Take this for what it's worth, but I've read that a 5/8 gp has a lower TOA than a vertical beam. So the 5/8 gp may reach out a little farther, but has no rejection, nullifying the receive signal. I've also read that a cubical quad phased vertical has a lower TAO than both ..... this is with all antennas at the same height.

Cebik doesn't agree with the quad theory however, and claims the yagi and quad have the same TOA. Also, Captain Kilowatt doesn't agree that a horizontal antenna has a lower TOA than a vertical.

So I don't know. I do know that antennas and antenna theory, fascinate me more than tweaking the last 5 watts out of a 40 watt radio.

 

[Robb]

"...running that beam vertically does it have a TOA still similar to the 1/4wgp/dipole or is the TOA affected by the reflector and driven elements ?" BootyMon
Yes; but why would you want to run it vertical? You don't see many Hams running their Yagis vertically. When a dipole is 1/4 wl above the ground - it then becomes bi-directional. Less than that - it is omni-d...

Polar pattern of a 1/2 gp to a 5/8 gp
Just for reference...

 

[Captain Kilowatt]

TOA has more to do with height above ground than any other parameter.

Moonraker Antenna Systems


Robb, it gets pretty hard to stack vertical yagis cut for the ham bands. That is the main reason why hams use horizontal, it makes them higher off the ground as well as making them more mechanically stable when stacking, Imagine the mast ot tower you would need for vertical mounting. It seems that CB'ers get all caught up in this V/H stuff and THINK that Horizontal is better but guess what? The polarity CHANGES ALL THE TIME and you have NO IDEA whatsoever what polarity the received signal is arriving at. I have seen a groundplane beat out a 4 element monobander when the polarity rotation was just right.

 

[hookedon6]

... the main reason why hams use horizontal, it makes them higher off the ground as well as making them more mechanically stable ....

and it helps to reduce the (manmade) electrical noise,.... most of which is vertical.

 

[hookedon6]

.... so a dipole has a radiation pattern similar to a heart (if you will)...
im obviously miss understanding or don't understand something here so take me to school guys .

if you feed TWO 1/4 wl verticals 90 degrees out of phase, you will get a CARDIOID radiation pattern

 

[W5LZ]

The 'shapes' of radiation patterns, which includes 'TOA', is dependent on height, environment, and almost every little thingy around any particular antenna being discussed (or 'cussed'). All the 'classical' drawings of the 'typical' radiation patterns for various 'sizes' of antennas (1/4, 1/2, 5/8, whatever) are ONLY generalizations to give a general idea of what they look like. They are NEVER exactly as shown and can be radically different in some circumstances.
[And then you run into the patterns that someone has optimized for some particular reason of their own. ]
I don't know about you, but I have a very difficult time trying to describe -any- particular radiation pattern! If it isn't 'round', 'football' shaped, or some very common everyday shape that people would recognize, my descriptions will sound like a 'pipe' dream of someone NOT smoking 'Captain Black' tobacco! I ain't doing that, or going to try describing one if I can possibly help it! It's much easier to show someone. Even better, is getting one'a them antenna modeling programs and finding out for your self (after you learn to use the @#$ thing!).
One 'trick' to try is to imagine that radiation pattern as a 3d figure, a balloon for instance. That's fine in 'free space', but not for down here where we are. Then you have to sort of imagine what happens when that balloon if compressed against the earth, taking into account just how 'much' any particular object/thingy contributes to that shaping thing because of charges, polarity, and who knows what else. (Sometimes a little of that 'smoking' stuff sounds really attractive, doesn't it?? Huh? Huh?)
And then theres the part that people don't seem to realize sometimes. The lowest 'TOA' isn't always where you are getting the received signal from, or where your signal will reach where it's wanted to go from. Nothing wrong with wanting a low 'TOA', but I'd also like to have some of them higher 'TOA's too. 'Momma Nature' is sort of fickle at times about that stuff. The 'TOA' alone is not a very good way of selecting an antenna.
- 'Doc

 

[GnG8d]

It seems that CB'ers get all caught up in this V/H stuff and THINK that Horizontal is better but guess what? The polarity CHANGES ALL THE TIME and you have NO IDEA whatsoever what polarity the received signal is arriving at.

I think that's where we are on a different sheet of music.

I was talking about HvsV only in regards to the TOA. I am aware that the signal will "barrel roll" before reaching the recieving station. But the lower the TOA, the less skips it takes to reach that recieving station.

 

[Marconi]

be for warned ..... im bored and ive been thinking again .......

it seems a vertical dipole and a 1/4 wgp essentially perform the same but just have a different ground element(s) configuration . and we know that 1/4 wgp's have a higher toa than 1/2 wgp's and that 5/8 and .64 wgp's are even lower . so a dipole has a radiation pattern similar to a heart (if you will) . beams are just a dipole with a reflector with differing numbers of directors spaced and sized accordingly .

running that beam vertically does it have a TOA still similar to the 1/4wgp/dipole or is the TOA affected by the reflector and driven elements ? im thinking it doesn't because if it did running it horizontal wouldn't it put its maxim tx and rx diagonally across the beam favoring the hot/radiating element ? wouldn't the pattern be similar to laying that heart shape down sideways ? then to get maxim tx and rx you don't actually point the beams beam directly (on axis) with the desired direction of communication , but (kinda/sorta) across opposing ends of the driven and reflecting elements ?

am i wrong from the start about the toa of a dipole ? does it radiate with a flat toa like a doughnut with no stronger lobes coming off the top giving it a heart shaped radiation pattern ?

im obviously miss understanding or don't understand something here so take me to school guys .

BM, can you post an image of what you visualize as a pattern? The image that Robb posted is way out of proportion and does not represent the patterns accurately for the antennas that I have seen or can imagine. This image is a drawing of someone's imagination as to what the patterns might look like. It might be alright as an example, but it is no where near close.

'Doc is right we can only guess as to what the pattern really is and modeling may have the theory for pattern shapes correctly understood and applied, but even that is subject to real world stuff that adversely effects the ultimate pattern, and he also talks about that messing up the best of ideas on image.

There may be some difference in the actual TOA of a 1/2 wave dipole when laid horizontal vs. vertical, but I bet it is not much---and for sure IMO it would be difficult to really tell just using your radio. The polarity affects alone are so much more powerful of an influence---so as to make your observations difficult to impossible to really tell just by comparison---and when using a dual polarity beam for sure.

The use of the 1/2 wave element in beams, yagi or quad, is probably due to their physical symmetry. The radiated pattern, vertical or horizontal, is not skewed as you imagine, being off to the side. The is because of the advantage of having improved symmetry---particularly with a multi-element beams where proper symmetry is so important.

Some will suggest that feeding a yagi using a gamma will ill-affect the pattern a little, just as you describe not straight down the boom. If you consider the wind alone, it can probably make more of a difference in your antenna being on or off target than the amount of skewing noted when using a gamma---even if there is skewing which I don't believe there is. In my experience the typical rotor does not hold the antenna that steady anyway. If even a slight breeze is blowing your beam can move a degree or more, so why worry about being that close on target when a few miles out being a degree or two off can make for being miles off from a true straight line.

Additionally, the typical 11 meter beam does not have a forward lobe that is IMO---really that narrow or tight. When I built my beam antennas I concentrated on the tuning along the boom and for match, because long ago I saw bad settings for spacing and tune that caused the antenna to be almost omni directional---and I wanted mine as directional as possible. It is tedious work and it takes time, but if you understand and watch for that response using your radio, you can tweak those multi-elements to work really well in a lot of cases. I did have several beams that didn't or wouldn't work out so well, but it can be done.

Show us some images of what you see in you mind, concerning this antenna idea---that is!

This is the way I see the three antenna designs represented in the image below. If you will notice low near the horizon that each antenna shows very close to the same RF magnitude, within 3 dbs as noted, but also notice that these representations are also over an infinite, conductive, ground plane and that makes a big difference compared to the real patterns over real Earth where the differences among them all are much closer to the same maximum gain.

I think you can click on the image and make it larger.

 

[hookedon6]

... the lower the TOA, the less skips it takes to reach that recieving station.

that can be a "double-edged sword". i have a low radiation angle antenna dedicated to working europe, it fine for europe but it really sux for "local" (n amer) contacts.

also a "high" angle antenna can just "punch thru" the f1/f2 layer and yor signal ends up on mars:blink: . so, keep an eye on the MUF

 

[Henry HPSD]

Hi guys,

On my homesite there is some info on t.o.a. wich migth be of intrest?
Now it is written down very simple but it migth be helpfull
11 meters DX antenna systems

kind regards,

Henry