Frequency Doubling Through Phasing

[silverfox]

This is just a general "I wonder question"; no particular project associated with the question. Obviously if the answer to the first question is- It doesn't work that way, then the other questions can be ignored. Seems to me though that as in the visible spectra the combination of frequencies produces a different colour than either of the two original frequencies.

If I have two RF sources at the same or close frequency and adjust the antennas to a separation distance of 1/2 wavelength apart, will this cause an interference wave at twice the original frequency to be created? I'm not thinking in therms of addition of waves, rather a new wave created resulting from interference reactions between the original waves.

Roughly, what is the relationship between the power of the new wave and the original source waves. 1/2, 1/10 the original power level if it worked?

If this principle works what happens to the frequency of the newly crated wave when the spatial relationship of the two antenna' is changed to something other than 1/2, to say 1/5 the distance of the wavelength in separation.

Okay what about using two different frequencies as the source? Do you get a mathematical fraction of the original frequencies?

silverfox.

[Ritchie200]

I don't think you would get a new waveform or one of different amplitude.  I think you may be comparing apples to oranges.  In your example about color, lets say we are talking about an RGB LED.  A combination of different individual color intensities will produce millions of colors - to the eye, at a distance.  Your eye is the receptor and processes the combination of what your see.  Combining notes on a guitar can give you pleasing results (unless it's a Tele) - to your ear.  Your ear processes the note combination as the receptor.  RF, I would think, is no different.  You still have the fundamental wavelengths, beating up your discriminator or VCO for dominance - IF that is what you are using for a receptor.  An oscilloscope would also show the individual wave lengths.  I'm sure there are all sorts of parasitic implications involved with antennas so close, but I would think it would only cause subtle changes or distortions to the primary wave form(s).

Jim

[PRR]

> two RF sources at the same or close frequency and adjust the antennas to a separation distance of 1/2 wavelength apart, will this cause an interference wave at twice the original frequency to be created?

Only if one of the antennas is rusty.

Distance (phasing) is unimportant.

Two tones into a NON-linear device will make sum and difference tones. That's how rock-n-roll works: two notes into an OVER-driven amplifier will make a third note (and others), a "chord". If the two notes are 440Hz and 444Hhz, you will get a 884Hz tone, which is "double". You also get a 4Hz tone, which is distressing; the "out of tune" beat (440 and 444 are almost the same and yet far enough off to be a mis-tune). For Rock we finger a couple notes on a wider interval so the beat tone makes a "musical chord" (albeit one which would annoy Bach).

[super&plexi]

I know...old topic, but I did respond ( at least I thought I did)... I guess it didn't take.  While my buddy had a vintage music store we used to fart around in there all the time... hooking up this amp & that amp & this  that and whatever.      So once I hooked up 4 phase45's in series thinking that a uni-vibe was a four-stage shifter so I needed 4 p45s to emulate one. With each one set a little off midpoint it gave a not unpleasing huge  swirl. At some points the volume would seem to increase greatly and at one point the signal completely dropped out as if canceling itself it only happened once completely but there were notable dips and increasest hroughout.... as long as the controls were set around Midway or less. Run fast, jthey just produced one big warble.

Does that relate somewhat to what you're talking about

[HotBluePlates]

... once I hooked up 4 phase45's in series ... At some points the volume would seem to increase greatly and at one point the signal completely dropped out as if canceling itself ...

Your experience was real & valid (also happens with "through-zero flanging"). However, you were working with audio frequency and silverfox was asking about radio frequency and antennas. So the experience with audio turns out to not be relevant to a radio and its RF input stage.