Extend RF range

Hello,

I got this from ebay.

http://www.ebay.com/itm/391079073447

The problem is that the range is really low. I used a cable (around 30cm) to connect the antenna on it and the range was extended to like 10 meters.

My questions are:

1)Is there any max. length for the antena? I mean if I use (lets say) 1m cable will the range extend more?
2)Is there any other way/tricks to extend the range?

also...forgot to mention about the connection of the antena...it maybe a little foolish but I don tknow if I connect it right.

I connect it only in the "slot" that says antenna...does the other side of the cable has to be connected too??

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Hello

The antenna should usually be about 1/4 of the wavelength. The site you provided indicated 31MHz, so that is a 1m wavelength. Your antenna should be about 25 cm long.

You should indeed connect it to the "ANT" slot.

What range do you get when you don't connect any antenna ?

I don't know of any tricks to extend the range, but maybe someone else will

w/o antena I get around 3m (good signal)
If I power the module with an external supply unit with more Amps (at 5V always) this wouldnt boost my range?

I need around 15-20m (I dont know if its possible)

If I power the module with an external supply unit with more Amps (at 5V always) this wouldnt boost my range?

No. You can't push power. You can only be sure that the power supply you use is adequate for all the devices that want to pull power.

Did you check the battery of the tx?

That looks like a 315Mz or 433 MHz module.
315 needs 23.8 cm antenna.
433 needs 17.3 cm antenna.
The length comes from 1/4 wavelength of the frequency used. The math involves 433 MHz, speed of light, and 4.
http://www.onlineconversion.com/frequency_wavelength.htm

I made a remote with 433 MHz Tx/Rx units, the antenna was just a piece of 30 guage wirewrap wire inside the plastic case holding a promini, keypad, RF module, and battery for the transmitter, and similar for the receiver but with more electronics to drive 7 segment displays.

CrossRoads:
That looks like a 315Mz or 433 MHz module.
315 needs 23.8 cm antenna.
433 needs 17.3 cm antenna.
The length comes from 1/4 wavelength of the frequency used. The math involves 433 MHz, speed of light, and 4.
Online Conversion - Frequency Wavelength Calculator

I made a remote with 433 MHz Tx/Rx units, the antenna was just a piece of 30 guage wirewrap wire inside the plastic case holding a promini, keypad, RF module, and battery for the transmitter, and similar for the receiver but with more electronics to drive 7 segment displays.

what was the range that you got?

What are you using for a receiver?

You need a wire, 23.8 cm long, connected to the antenna connection of both the transmitter and the receiver. It is best if both antennas are vertical.

Don't use a "cable" between the antenna and the device.

The receiver is clearly a cheapo one feeding that decoder IC. I've had extremely disappointing performance with the cheapo receivers. Range is extremely poor sometimes (I've at times had range of 10-25 meters sometimes, but other times range of 10-25 centimeters...)

I have had much better results with the ones with the SYN470R receiver chip (they're the narrow yellow ones with the SOIC-16 chip on them, from ebay), using the same transmitters. However, I haven't seen any that have a decoder chip on them as well, to translate the data coming off the air into 4 on/off channels.