2.4GHz extension for RC

Thread Starter

Lklineberg

Joined Jul 11, 2021
11
Hello everyone, hope this post finds you well!

I’m a very green in this field so please forgive my ignorance :)

We just purchased a ride-on car for our toddler, everything works well but the distance between remote and car is limited by approx 30ft which we were hoping to extend.

Please help me identify where one would solder on an antenna to this PCB or if it’s even possible and thanks in advance!

Cheers!
Logan
 

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Papabravo

Joined Feb 24, 2006
16,820
Why do you think you can solder an antenna onto the PCB? It will more than likely upset tuned circuit on the PCB, consisting of the long trace along the top of the board with the two squiggles in it. I'm guessing you lack the equipment you would need to make a matching network for whatever antenna you have. If I was doing it, I would cut the long trace and match the antenna to what is left on the board -- probably capacitors. It would still take some pricey equipment to do it right.
 

Thread Starter

Lklineberg

Joined Jul 11, 2021
11
Why do you think you can solder an antenna onto the PCB? It will more than likely upset tuned circuit on the PCB, consisting of the long trace along the top of the board with the two squiggles in it. I'm guessing you lack the equipment you would need to make a matching network for whatever antenna you have.
You’re very right, I lack the tools and skills to determine anything about this circuit board let alone where the existing antenna even exists.

I was hoping it would be as easy as soldering on a line to an antenna to extend the range. Beyond that I would be at a loss. :/
 

Papabravo

Joined Feb 24, 2006
16,820
You’re very right, I lack the tools and skills to determine anything about this circuit board let alone where the existing antenna even exists.

I was hoping it would be as easy as soldering on a line to an antenna to extend the range. Beyond that I would be at a loss. :/
You could probably still run the experiment, but I might not be able to tell you how to interpret the results. Things get very trick in that frequency range.
FYI: The wavelength at that frequency is

\( \lambda\;=\;\cfrac{c}{f}\;\approx\;\cfrac{3\times10^8}{2.4\times10^9}\;=\;0.125\;\text m\;\approx\;4.92\;\text{in.} \)

Anything you do on the order of 1/2 or 1/4 of a wavelength could have a dramatic effect on the results. This stuff is really sensitive to geometric features which is is why it doesn't pay to fool around unless you have some concept of what you are doing. You might have better luck making a directional antenna for the transmitter.
 
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Thread Starter

Lklineberg

Joined Jul 11, 2021
11
You could probably still run the experiment, but I might not be able to tell you how to interpret the results. Things get very trick in that frequency range.
FYI: The wavelength at that frequency is

\( \lambda\;=\;\cfrac{c}{f}\;\approx\;\cfrac{3\times10^8}{2.4\times10^9}\;=\;0.125\;\text m\;\approx\;4.92\;\text{in.} \)

Anything you do on the order of 1/2 or 1/4 of a wavelength could have a dramatic effect on the results. This stuff is really sensitive to geometric features which is is why it doesn't pay to fool around unless you have some concept of what you are doing. You might have better luck making a directional antenna for the transmitter.
That wavelength formula looks like Greek to me :) I don’t even know what the variables stand for without a google search.

If I were to create a directional antenna, wouldn’t that need to be soldered on to the board somewhere?
 

Thread Starter

Lklineberg

Joined Jul 11, 2021
11
Any possible range extension would be beneficial for my marriage. I have a bum knee and can’t run after the car for long and my wife always has to take over. :D
 

Papabravo

Joined Feb 24, 2006
16,820
I used one Greek letter, and you knew it was a Greek letter (good on you). The product of the wavelength in meters, λ, and the frequency in Hertz, f, must be equal to the speed of light, c, expressed in meters per second. A bit of algebra allows you to compute the wavelength by dividing the speed of light in meters per second by the frequency in Hertz to get the wavelength in meters. So I did that for you.

The directional antenna I was thinking about would be on the transmitter as opposed to the receiver. That way all you have to do is point the antenna where you want the signal to go.
 

Thread Starter

Lklineberg

Joined Jul 11, 2021
11
Thanks Papabravo, directional antenna option sounds like it would help! In laymen’s, how would I accomplish that on this board?
 

LesJones

Joined Jan 8, 2017
3,497
Why would the receiver have push buttons on it ? I think that is the transmitter. Can the TS confirm if the board in the picture is the item you hold in your hand to control the car. (Transmitter.) ? Or is it part of the car that receives the commands and gives you control of the car from the hand held unit ?

Les.
 

Thread Starter

Lklineberg

Joined Jul 11, 2021
11
Why would the receiver have push buttons on it ? I think that is the transmitter. Can the TS confirm if the board in the picture is the item you hold in your hand to control the car. (Transmitter.) ? Or is it part of the car that receives the commands and gives you control of the car from the hand held unit ?

Les.
Les, this is the board inside the remote control device with 7 buttons you hold in your hand to send commands to the vehicle (directional pad with forward, reverse, speed selection and emergency stop before you drive off a cliff)
 

Papabravo

Joined Feb 24, 2006
16,820
OK - my mistake, I thought the picture in the original post was the receiver. If you are going to experiment with an external antenna you should cut the trace which forms the PCB antenna as close to the capacitors as possible and connect the external antenna to the transmitter output and GROUND. If this does not work for you can always go back and create a solder bridge across the cut.

I think you want to avoid having the transmitter output trying to drive the PCB antenna in series with an external antenna. It is possible it could work, but I would not expect that result. Even with a crappy SWR match I don't think the power levels are high enough to damage the transmitter output.
 

Thread Starter

Lklineberg

Joined Jul 11, 2021
11
Also to note, the remote is powered by two AAA batteries (not even sure if they’re in series or parallel). If all else fails, if I’m understanding correctly, I could solder the section removed in the aforementioned X and re-establish the on-board antenna link.
 

LesJones

Joined Jan 8, 2017
3,497
One type of directional antenna that may be simpler for you to construct than a yagi is a cantenna. You will find more information on this type of antenna with Google. This is a link to one article on the design and construction.
I suggest looking at the data sheet for the transmitter IC. This may give information an matching it's output to a 50 ohm transmission line. (Coaxial cable.) The picture is not clear enough to read the part number of the ICs so I don't know which IC is the transmitter RF part.

Les.
 
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