extend rf receiver range

could someone tell me how to extend this receiver's range?

http://www.ebay.com/itm/291359887420?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

the antenna is a small coil.. what and how should I solder to it?

Thanks!

1/4 wave dipole is the simplest. A wire 17 cm long (assuming that's a 433 MHz receiver) soldered to the point marked "ANT" on the board.

Russell.

It's also a transmitter. With that, the antenna circuit impedance is critical and has to have a good load match to avoid return losses, or excessive VSWR. So you might unbalance the TX circuit and kill the transmit range if you're not careful. Also, with a 1/4 wave monopole, the circuit board itself (and whatever it's connected to) becomes part of the antenna because the feed is unbalanced. A practical 1/4 wave monopole antenna generally is mounted on an extended flat ground plane to avoid that.

Also just as an FYI, some devices antennas are deliberately limited by the FCC certification requirements for the frequency band it operates in. So if you modify it, you can not legally use it. At the very least, you may not exceed a certain ERP (effective radiated power).

aarg: It's also a transmitter.

You must be looking at a different one to me. The one linked to has a transmitter with a telescopic antenna and a separate receiver.

Russell.

russellz: 1/4 wave dipole is the simplest.

¼ wave whip.

Not dipole (which would be ½ wave).

Sorry’ l’Oise terminology!

Russell

And... don't solder anything to the coil. Solder it, as suggested, to the terminal marked "ANT".

I did not see in the first post what range the OP has, and what range he wants. 433Mhz devices are typically/legally short range devices. To open a car door, garage door, or control appliances inside your house. Be happy if you have 10meters inside/ 100meters outside. Extending the range beyond that could upset the lives of others. Leo..

Okay, the transmitter is the thing in the leather pouch... my bad. In that case, 1/4 wave wire is a good plan. But reception is also influenced by so many different factors... antenna orientation, nearby metallic objects, device grounding, interference from other RF sources etc... If you want the absolute best reception, you'll have to experiment with all those too.

But it won't get dramatically better. It will quickly lead to diminishing returns.

you could also get an amateur radio license and use power up to 1500 watts, unless you are in restricted areas, then 100 watts, or so.

Paul

Wawa: Extending the range beyond that could upset the lives of others.

Irrelevant (and thoroughly muddled it seems)! We are talking here about enhancing the range by adding an effective antenna to the receiver.

If you look at the description |500x344 you will discover that the transmitter already has a plausible antenna.

turned out to be 315mhz, I soldered on a 23.8cm antenna, works to 100yrds

bonanza243:
turned out to be 315mhz, I soldered on a 23.8cm antenna, works to 100yrds

Where are you based? I believe that frequency is only permitted in the USA?

Russell.

bonanza243:
turned out to be 315mhz, I soldered on a 23.8cm antenna, works to 100yrds

The message here is of course, the absolute poverty of information on eBay.

That receiver module was never intended to be operated without an antenna.

And when using the term “extend this receiver’s range”, bonanza243 did not tell us just what range he did obtain with no antenna. (The coil is a coil, not an antenna, of course. :grinning: )