What is this thing and can I cut it off?

[Bustedaw11]

We should have a dedicated thread to discuss this topic in depth.

 

[Jerold]

Stick with the antenna length that corresponds with the middle of said frequency range. The frequency we use is high enough for a few millimeter difference ,to throw your antenna into another band.
Also antennas are half wave because of the alternating of waves: Plus-Minus.
A full wave antenna length will work on half the frequency, not on ours. If it still does, at least performance will be poop.

1/2 wave because of alternating waves, I'm not following you?

Are you talking about 1/2 is above the line and 1/2 is a below it?

 

[Bustedaw11]

Check this out- i got a decent laugh.

 

[SirCrashALot]

1/2 wave because of alternating waves, I'm not following you?

Are you talking about 1/2 is above the line and 1/2 is a below it?
View attachment 308255

Yes

 

[Jerold]

Yes

That's the amplitude not the wave length. The wave length is the time is takes to complete one cycle the symbol is ʎ.

In an ideal world a tuned antenna is some fraction of the wave length. The (full) wavelength of 24.G is 300/2.4 = 125mm if you divide that by 1/4 you get 31.25, which is what we typically see for RC. Since the Radiolink uses a dual antenna, aka dipole, it doubles the length and becomes a 1/2 wave antenna. The larger the fraction you have the more gain you get. Gain is good for distance. That's probably part of the reason Radiolink works at 600m.

But that math is all done in an ivory tower in vacuum. i.e. not the real world. Watch the video above you'll get the idea. His final word is you don't know how they designed it and the "exact" length isn't what you think it is. The design involves some very expensive equipment with a bunch of P.h.ds to get them just right.

As an example of how much it doesn't matter, and what we don't know is your car radio. It can receive 87.5-108 MHz FM and 525 to 1,705 kHz AM all from the same antenna. Filters and amplifiers do a lot for signal quality.

Just cut it close to what it was it (30,31,32, whatever) will be fine. Or you might have to cut it again, or worse case spend $10 on a new receiver. . . unless you run Futaba.

Antenna placement and orientation are far more important than that +/- 1mm.

 

[SirCrashALot]

That's the amplitude not the wave length. The wave length is the time is takes to complete one cycle the symbol is ʎ.
View attachment 308332

In an ideal world a tuned antenna is some fraction of the wave length. The (full) wavelength of 24.G is 300/2.4 = 125mm if you divide that by 1/4 you get 31.25, which is what we typically see for RC. Since the Radiolink uses a dual antenna, aka dipole, it doubles the length and becomes a 1/2 wave antenna. The larger the fraction you have the more gain you get. Gain is good for distance. That's probably part of the reason Radiolink works at 600m.

But that math is all done in an ivory tower in vacuum. i.e. not the real world. Watch the video above you'll get the idea. His final word is you don't know how they designed it and the "exact" length isn't what you think it is. The design involves some very expensive equipment with a bunch of P.h.ds to get them just right.

As an example of how much it doesn't matter, and what we don't know is your car radio. It can receive 87.5-108 MHz FM and 525 to 1,705 kHz AM all from the same antenna. Filters and amplifiers do a lot for signal quality.

Just cut it close to what it was it (30,31,32, whatever) will be fine. Or you might have to cut it again, or worse case spend $10 on a new receiver. . . unless you run Futaba.

Antenna placement and orientation are far more important than that +/- 1mm.

I know.
X-axis=wave length
Y-axis= Amplitude.
I don't see what i said wrong.
Anyway you are correct.
For me, it's 27 years ago that i learned this antenna tech. We were into CB radio, VHF, UHF etc. Made some nice connections with all kinds of radios. Most of those weren't even legal to begin w
Good times.

That's the amplitude not the wave length. The wave length is the time is takes to complete one cycle the symbol is ʎ.
View attachment 308332

In an ideal world a tuned antenna is some fraction of the wave length. The (full) wavelength of 24.G is 300/2.4 = 125mm if you divide that by 1/4 you get 31.25, which is what we typically see for RC. Since the Radiolink uses a dual antenna, aka dipole, it doubles the length and becomes a 1/2 wave antenna. The larger the fraction you have the more gain you get. Gain is good for distance. That's probably part of the reason Radiolink works at 600m.

But that math is all done in an ivory tower in vacuum. i.e. not the real world. Watch the video above you'll get the idea. His final word is you don't know how they designed it and the "exact" length isn't what you think it is. The design involves some very expensive equipment with a bunch of P.h.ds to get them just right.

As an example of how much it doesn't matter, and what we don't know is your car radio. It can receive 87.5-108 MHz FM and 525 to 1,705 kHz AM all from the same antenna. Filters and amplifiers do a lot for signal quality.

Just cut it close to what it was it (30,31,32, whatever) will be fine. Or you might have to cut it again, or worse case spend $10 on a new receiver. . . unless you run Futaba.

Antenna placement and orientation are far more important than that +/- 1mm.

Oh, forgot to add.
Length of the antenna is especially critical for transmitters. When the antenna length is too far off, the transmitter will heat up and pop.
The receiving end not so much.
You could stick a fork in the antenna jack and you could still listen to your radio, or multi band scanner. But those are meant for audio transmission. That's not critical at all, since we humans can distinguish what's being said even when the audio is almost drowning in white noise. Remote Control not so much.

 

[dure16]

Antenna placement and orientation are far more important

Any tips for placement and orientation?

 

[Dan B.]

That's the amplitude not the wave length. The wave length is the time is takes to complete one cycle the symbol is ʎ.
View attachment 308332

In an ideal world a tuned antenna is some fraction of the wave length. The (full) wavelength of 24.G is 300/2.4 = 125mm if you divide that by 1/4 you get 31.25, which is what we typically see for RC. Since the Radiolink uses a dual antenna, aka dipole, it doubles the length and becomes a 1/2 wave antenna. The larger the fraction you have the more gain you get. Gain is good for distance. That's probably part of the reason Radiolink works at 600m.

But that math is all done in an ivory tower in vacuum. i.e. not the real world. Watch the video above you'll get the idea. His final word is you don't know how they designed it and the "exact" length isn't what you think it is. The design involves some very expensive equipment with a bunch of P.h.ds to get them just right.

As an example of how much it doesn't matter, and what we don't know is your car radio. It can receive 87.5-108 MHz FM and 525 to 1,705 kHz AM all from the same antenna. Filters and amplifiers do a lot for signal quality.

Just cut it close to what it was it (30,31,32, whatever) will be fine. Or you might have to cut it again, or worse case spend $10 on a new receiver. . . unless you run Futaba.

Antenna placement and orientation are far more important than that +/- 1mm.

RadioLink wants the antennae mounted at 90° to one another. Some have said this is more critical in an aero environment because you’re dealing with true 3D axis movement and as such that placement can keep the signal from dropping if one antenna is obscured by the attitude of the aircraft. Others have said it should be adhered to on surface vehicles as well. A ton of people use the R6GS for speed running and I’ve seen a hundred YT vids with the antennae placement all over the place. It doesn’t seem to hurt range appreciably in a real world environment. Thoughts on this dual-antenna 90° placement?

Any tips for placement and orientation?

Most say higher is better. I’m curious about the orientation as well. As for placement, as far away from the motor and ESC as possible. I’ve heard that some motors are much “noisier” than others, electrically speaking, but that any electronic components can cause interference to a certain degree.

 

[Jerold]

Any tips for placement and orientation?

Ideally they are perfectly aligned vertically, but that never happens. because they get swept back a bit on the car and I never hold the radio perfectly vertical. So I try to stick them straight up if I can. But if not it will only effect range.

For placement keep the exposed end away from the other electronic bits, metal and conductive things like carbon fiber, aluminum surfaces. When I was testing my Limitless for the first time I just let the second antenna lay on the pan and it was near the motor. It can shield or glitch the radio signal. Luckily this is digital and can detect those things and either ignore or correct them. Then throw a code for you and stop.

Line of sight is best and (as @Dan B.) pointed out higher is better. They high frequency is easily block by all kinds of things they do bounce a bit, so it's not a finite distance.

All this stuff matters when you are at the very end of the range. For bashing it shouldn't be any issue. My speed run street is 1600' (800' in each direction) and I haven't had any issues.

I don't see what i said wrong.

You have a respectable background and said nothing wrong. I just didn't understand what you were referring too the with +/-. Thinking more about this I'm assuming it was the + is 1/2 and the - is the other half? I just never thought of it that way but it works as well.

The modern radios have so many filters, amplifiers and error corrections it's ridiculous. I hit a base station like 8 miles way from my HT with 5" antenna in a urban environment. Ok that was like 5W, but still pretty amazing.

 

[SirCrashALot]

You have a respectable background

Aaaaaaw. You're making me blush