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433.92 MHz preamplifier for a remote control system

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polarized

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433.92 mhz antenna

Hello,


Would it be possible to design a 433.92MHz preamplifier in order to increase the sensitivity of the receiver. The complete system serves as a wireless garage door opener and at the moment it is capable to achieve about 200 meters distance. It has a handheld transmitter, so it is not possible to modify it in order to achieve greater distance, because of the limited space and the battery consumption. The RF receiver board is made with SMD elements and it uses the integrated circuit UAA32017 from Philips. I do not know the signal to noise ratio of the receiver nor the input sensitivity. Is it possible to increase the distance to aprox. 400 meters and how would the electrical circuit look like. The receiver has an antenna connected to it and the antenna lenght is around 32 cm.



Regards.
 

433.92 mhz

You would be better off improving the antenna gain and height. Consider putting the receiver on a pole above the girage and running the power up to it and the control signal down from it on a cable. Try to find a gain antenna for this frequency range. Are you going to use it from a specific direction? A directive gain antenna would work.

There are problems with incresed range. Other users in the area could open your girage when you are away if they have the same code as you.
 

433.92 mhz transmitter schematic

Hello,

The antenna is already positioned above ground aprox. 9 meters. Altough the system is originally intended as a remote garage door opener it is not used like that, but instead in a application which does not allow the easy usage of a directional antenna, because it has to cover a wider area angle.



Regards.
 

433.92 antenna design

You could use a ham antenna such as these **broken link removed** as well as a mast mounted amplifier at the antenna.
 

433.92mhz antenna

Hi polarized,

normally the S/N ratio of such receivers is not too bad. So the best way is to use an antenna with more gain or a sharper beam. The use of an external low-noise amp will be difficult. You have to achive 6dB more gain by identical noise and this will be nearly impossible.
Perhaps it's really the better idea to improve the output-power of your transmitter by 6dB. This should also work with a battery and is easier to implement than the other variants.

Bye
 

433.92mhz antenne

The cable loss for RG-58/U cable would be 3 dB. Thus a 1 dB noise figure mast mounted amplifier woudl reduce the system noise figure by about 3 dB.
 

433.92 mhz lna amplifier

Hi mr_ghz,




Do you have an electrical schematic of a circuit which would add extra 6db of power to the transmitter section in the 433 MHz band?It should be very small in dimension. What would be the size of a directional antenna which has better gain when compared to a standard lambda/2 antenna which in this case is 34 cm long? What do you think regarding a preamplifier made with an HEMT transistor, like the design here **broken link removed**


Regards.
 

433.92mhz lna circuit

Hi flatulent,



The RF area is not my area of expertise, so what would be the mast mounted amplifier you mentioned? Is this amplifier located very close to the antenna itself or it means something different? And I did not really understand you when you correlated the noise figure with the cable loss?What action do you recomend for this problem?


Regards.
 

top 433.92mhz

The transmission line attenuates the signal. You can buy an amplifier for the 70 cm ham band tht will fit at the antenna end of the line and be powered from a box at the receiver end. This will provide a little help for your system. The main help would be a gain antenna like the one in the link above.
 

433.92 antenna lenght

Hi polarized,

1. (schematic of amp)
You wrote that the RF area is not your area of expertise. So I would recomend you using a complete amplifier chip. This could be a MSA-2643 from agilent. This chip gives you a gain of 16dB and a max. output power of +9dBm. The size is about 2*2mm. In the datasheet (**broken link removed**) there are also some examples.

2. (size of an antenna)
It depends on the gain you want. Look at 70cm pages, they often sell yagi antennas with 3 or more elements. They would have enough gain. The size is about 35cm in broadside and the same (or more) in length.

3. (PreAmp)
I think it's possible to use this circuit mast-mounted. But I don't think that this will extend your range enough. This amplifier has more than 10dB gain but it will also amplify the noise. So your S/N won't get better than 2-3dB and you should have 6dB...

Bye
 

i'm not sure which rf remote control you want, but if you're looking for some garage door remote control solution or if you need any RF Remote Control, RF Transmitter and Receiver Module, RF Remote Control Switch, please feel free to contact us at solidremote

---------- Post added at 15:33 ---------- Previous post was at 15:33 ----------

the link to solidremote is here RF Remote Control, RF Transmitter and Receiver Module, RF Remote Control Switch
 

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