blackrectangle123
16768
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A sinusoidally-excited dipole antenna radiates equally in all directions perpendicular to its axis. The xz view is the "side view" which shows the length of the antenna, and the xy view is the "top view" which looks down along the antenna axis. The middle plots show two antennas spaced a quarter wavelength apart, with their electrical excitations offset by 90 degrees. This "directional array" radiates preferentially toward one side. The right plots show four antennas, spaced by a quarter wavelength and with a 90-degree electrical shift between adjacent antennas (basically, just an extension of the two-antenna case). The main beam gets even tighter and more focused, but this comes at the expense of the radiation pattern developing "side lobes" which are visible in the xy view. The total input power is the same in all three cases, to make a fair comparison.
afambelafonte
Screw it. To the front page!
dobroweigh
Potatosuperhero
Sigh... *unzips*
redtails2649
You're a fuckin wizard, Harry
ComoSeIguana
CPK3
Entrainment.
DrewThe3DPrinterGuy
scuba7jb
I'm not sure what to do with this information...
fightmeeh
Yagi-t used to it.
Manusho
You know what to do.
LokiOnTheCouch
afambelafonte
You don't have to do anything
SmashySashimi
At the risk of not understanding a dang thing, what determines which side gets the preferential treatment?
innagaddavidababy
The antenna that is delayed the most is the one in the direction the beam points. The other antenna(s) signal “catches up” in that direction.
blackrectangle123
Whether the 90 degree electrical shift has a positive sign or a negative sign
Cactus21
Does the resulting directional array change if you vary the power on one or more antenna versus the other? I assume your pics are for the same power output on all antenna.
blackrectangle123
Yes, all the antennas have the same power in each array. I have heard that it is possible to minimize the side lobes by giving different excitations to the different antennas in the array. So yes, I believe that is a thing
obarey
It's not only power, but also how you modulate them. With an array of e.g. 3x3 antennas, you can direct your beam without having any mechanical movement.
TheUnstoppableWampas
Hey maybe you'd know. I have 2 quite clever electrical engineer friends that both treat antenna design like some form of extra evil black magic. I've seen and call their regular electrical engineering work black magic even though I'm just a different kind of engineer. Electrical engineers are the kind of engineer that do antenna work, so why do you think they treat that part of electrical engineering like the shadow lands that one must never visit?
imaynotbeasmartmanjenny
Frequency is a lot different than ohms and resistors and working with waveform in an atmospheric sense can be daunting given the task
blackrectangle123
I think it may be because antennas get you into the area of "electrodynamics", where the emag equations are expressed in their full glory, with wave propagation and all. The basic EE curriculum starts with electrostatics and then goes into AC steady-state, which is kind of a quasi-static regime. Microwave engineering gets one a bit closer to electrodynamics, but still not quite all the way there. So it depends on what kind of EE they do.
TheUnstoppableWampas
It's that bad huh? Well you seem to like it. What drives you to understand it? It has always seemed so perplexing the way they talk about it. Maybe if I better understand the perspective of someone that likes it I can get a little closer to understanding my friends aversion to it.
blackrectangle123
I was arrested at the "static" and "quasi-static" levels for many years, and I wanted to see EM theory in its full glory, so antennas are a great way to explore that. Now maybe your guys are actual antenna design engineers and they have to worry about all the nuances of beam forming, ground effects, etc. In which case it is indeed black magic. My simulation here is a "free space" version with no coupling to a surrounding environment.
TheUnstoppableWampas
One of them got an antenna design job right out of MIT in the 70s. Only lasted a few months before seeking work elsewhere so I know at least one of them did understand antenna EE work. The other one does grid work, and only spoke about antennas from course work in EM fields who said, and I quote "You can't make me work on antennas. I won't go back!" Thanks for you insights.
dobroweigh
A plain electrical engineer works with electrical circuits which they can break into components and write down on paper. A real antenna (or RF circuit) is something you may only approximately break into components. Because each part of the circuit has its inductance and capacitance relatively to all other parts. There are many ways to "formalize" it. There are no magic glasses you can put on to see where you was wrong in doing so (because you were). It's a cool field but a rather difficult one.