RF remote control for PC
RF remote control for PC
(OP)
Hi all,
I'm building an RF remote control for a PC and have the following constraints:
-The maximum frequency my scope is able to view is 50MHz, so it sets the maximum frequency of the carrier. In my case it is 43MHz.
-The case is 8*10*3cm => the maximum size for the antenna is 10 cm (I don't want any external antenna)
-The supply voltage is 3V. Oscillation amplitude is 1V peak to peak at the antenna feeding point.
-The carrier is ON-OFF amplitude modulated with a PIC.
Actually my problem is that I have very poor range. I need 3-5 meters, but I have only arround 50cm.
If a connect a wire that is 1/4 wave length long, then the range is OK. The problem comes from the fact that I don't know what kind of antenna to build that will fit in the case and will be efficient enough.
-So my question is: what is the best antenna and how to match it?
-How can I improve the range of the transmitter even if the antenna is very ineffective?
I'm building an RF remote control for a PC and have the following constraints:
-The maximum frequency my scope is able to view is 50MHz, so it sets the maximum frequency of the carrier. In my case it is 43MHz.
-The case is 8*10*3cm => the maximum size for the antenna is 10 cm (I don't want any external antenna)
-The supply voltage is 3V. Oscillation amplitude is 1V peak to peak at the antenna feeding point.
-The carrier is ON-OFF amplitude modulated with a PIC.
Actually my problem is that I have very poor range. I need 3-5 meters, but I have only arround 50cm.
If a connect a wire that is 1/4 wave length long, then the range is OK. The problem comes from the fact that I don't know what kind of antenna to build that will fit in the case and will be efficient enough.
-So my question is: what is the best antenna and how to match it?
-How can I improve the range of the transmitter even if the antenna is very ineffective?





RE: RF remote control for PC
Dan
Owner
http://www.Hi-TecDesigns.com
RE: RF remote control for PC
But 5m is trivial. It's likely that there is something else wrong other than the antenna.
Also, couldn't you purchase Bluetooth user devices?
RE: RF remote control for PC
You could also try connecting your remote antenna to your hand by adding a metal strip onto your remote control box exterior.
As some of you may recall adjusting rabbit ear antennas at home on TV to improve the signal. TV channel 2 is 53 Mhz I believe.
I would think that antenna improvement combo would help the range alot.
kch
RE: RF remote control for PC
VE1BLL, because of the relatively small amplitude of the carrier when it is ON, the radiated power if 100% efficiency is achieved will be only 0.5*0.5/1.41/33 = 5mW with a quarter wave antenna.
But because of my very ineffective antenna this power may be only 1% of the above value.
Using the computer power wires as receiving antenna is certainly not a bad solution, but my receiver is external (attached to RS232) and I don't have any problem with antenna on this side because I can make it as long as I want.
What do you think about make the carrier amplitude higher? Instead of having only 1V peak to peak, if I make it 6V peak to peak, the radiated power will be greater because the radiation resistance will remain the same?? Or I am wrong?
RE: RF remote control for PC
RE: RF remote control for PC
RE: RF remote control for PC
So I need to build a montage that takes the 1V peak to peak HF signal and by impedance conversion produce a higher amplitude signal.
The input impedance of the system should be 100ohms, the output 5K.
It sounds like a step-up transformer, but how to build it???