10ft range on 433mhz radios? [solved]

I have 433mhz rx and tx units connected to a receiver and a transmitter (obviously), they work flawlessly when they are less than 10 ft away, but when they are further a way from that, they don't work.

I have soldered on a 15cm copper wire to the antenna.

I am using these units:

http://www.amazon.com/SMAKN%C2%AE-433Mhz-Transmitter-Receiver-Arduino/dp/B00M2CUALS/ref=sr_1_1?ie=UTF8&qid=1430629191&sr=8-1&keywords=433mhz

Hi, I'm using those and had similar range, until I built proper antennae. Get some RG-174 cable, strip at least 20cm of the outer insulation. Then push the braiding back, over the external insulator, all the way. It will now look like a reversed sock over the cable. Leave 17cm of rollled over braiding and 17cm of inner cable, trimming any excess. Cover it with a heat shrink.

Now I'm getting data from three floors up, flawlessly. In a concrete built building.

|500x417

PS. Also increasing the Tx's voltage, increases the range.

You might also want to take a look at this: http://forum.arduino.cc/index.php?topic=216524.0

^^ first time I see this aerial mentioned on this forum. I use it every time with my radios, and know it as a "sleeve aerial". Correct final length of [u]each element[/u] is 22.6cm for 315Mhz, and 16.5cm for 433Mhz. I shove it in a plastic pipe and hang it up. Best final cable length (for most types of coax), measured between the start of the braid and the receiver, is 63cm for 315Mhz and 46cm for 344Mhz. Or multiples of that. Leo..

Hmm, that's huge. I need this to fit inside of a wall switch....

http://forum.arduino.cc/index.php?topic=216524.msg1937838#msg1937838

I was looking at the curled wire, does it matter what the diameter of the curl is? Or can I just wrap some wire around a bic pen?

I only use coils on my transmitters, and the sleeve aerial on the receiver (more important). Just had a look at a 315Mhz receiver. ~13turns of plastic insulated solid core wire on the shaft of a 5.5mm drillbit. Coil length ~13-15mm. Leo..

Initially I tried with rg-178, that is thinner. But... never managed to sleeve the braiding. Too stiff.

So for the coil, the actual wire length is the same? 16.5cm for 433?

Just have measured a 315Mhz coil by pulling it straight. 30cm of wire. I guesstimate it could be 22cm for 433Mhz. I always re-wind on the smooth part of a drillbit. Leo..

If it may be of any help, the coil antenna that comes with these 433 modules, (which by the way I would categorize as a total waste of money), has 24 turns of .6mm wire and a 3.4mm internal diameter. That would calculate to 25.6cm, or (guessing), 26 to 27 cm of actual turned wire length. |500x281 BUT, their range never exceeded 2-3 meters and that, only if I was not standing in the middle...

Thanks the information, guys.

Im not sure I understand your last post, tz... are you saying that the coil method doesn't improve range?

also, assuming that for what ever reason I have to go with the rg 178 cable, if I wrap it up inside of a box, is that OK or does it have to be straight?

Also, would the best option be just to buy a higher quality radio, considering that the most important thing is to keep everything smallish?

Google "quarter wave antenna" and "rubber duck antenna" to learn about these antenna designs. A transmitting antenna should be in resonance to work at all well so the dimensions are critical. Receiving antennas are less sensitive due to the low Q of typical receiver input stages.

@Qdeathstar, I never really tested them on the same TX as yours. I already had way better performance with a whip of wire on them, than I ever got with the above (blue) tx and the coiled antenna. So I may not really tell, if they are going to be an improvement. From my tries the combination with the above photo's tx (blue) is a disaster. But that doesn't necessarily mean that the antenna is the culprit. Being new to all this myself, I've pretty much reached the limit of my, very limited, knowledge and experience on this topic... All the best!

I tried a 22cm coil wrapped around a 3/16 drill bit (which is ~4.5mm diameter) for the TX and a 25cm whip for the rx, but that actually made the reception worse...

The 17cm antennas provide the same results as the 22cm and 25cm antennas.

Wall switch? Then you have a whole wall to play with. Stuff the cable up inside the wall cavity.

NO, if you coil it the length is not the same. Open up your garage door remote and copy the antenna inside that. It's probably 433MHz. The diameter of the coil is just as important as the length.

http://s2.postimg.org/5sepgode1/image.jpg

the antenna is the yellow cable on top, this is the rx

and the tx

http://s22.postimg.org/qicxcd6up/image.jpg

MorganS: Wall switch? Then you have a whole wall to play with. Stuff the cable up inside the wall cavity.

NO, if you coil it the length is not the same. Open up your garage door remote and copy the antenna inside that. It's probably 433MHz. The diameter of the coil is just as important as the length.

I know, when I coiled it, I used a 22cm length around a 3/16" drill bit on the tx side. On the rx side, I used a 25cm straight coil.

this is what the coiled antenna looked like. I soldered it on right where it becomes straight at the end.

http://s8.postimg.org/k975whzhx/image.jpg http://s8.postimg.org/98c0rh791/image.jpg