Rfx Visonic receiver antenna

Post by **Juande** » Fri Oct 26, 2007 1:20 am

Hi All

Good to see you in that great site

I have a 492Mhz Visonic USB receiver and I'm experiencing problems with the receiving of signals of remote rooms. It seems that the default wire antenna is not enough to receive signals

I have read the documentation and it is mentioned that the wire antenna can be changed by a 50 ohm coax antenna.

My question is, how this can be done? Can someone send me detailed instructions on how to do that?

I have seen J1 and J2 ports in the PBC, but I do not know how to connect them to the coax antenna.

Will the reception be improved with this?
What is the size of that cable that I must use?

Many thanks in advance

Best regards

Juande

Post by **b_weijenberg** » Fri Oct 26, 2007 9:14 am

Juande,

492MHz is a non existing receiver. I suppose you have a 868.95MHz Visonic receiver?

Receiving sensitivity depends also on the location of the antenna. This is also valid for the wire antenna. Try to put the USB-receiver as high as possible and not to close to the PC. The PC is producing RF noise which has a negative effect on the receiver sensitivity for RF signals.

J1 is where the wire antenna is connected to. This is the hot side and must be connected to the inner conductor of the coax cabel. The outer conductor must be connected to J2. On the backside this J2 is connected to the receiver ground layer.

On the CD delivered with the receiver you will find also a document "Assembly instructions Groundplane antenna".
The construction for a 868.95MHz antenna is the same as the antennas described in this document except the total length of the radial is 8.75cm. And the reflectors are 8.6cm

You need a high quality coax cable and keep this cable as short as possible otherwise the cable loss will drop the positive effect of the GP antenna.

Another solution would be to use the receiver in an Ethernet interface. This interface can be placed at the best position for receiving all sensors and keyfobs in your house. The keyfobs have a very low output and the receiving range for this devices is short.

Bert

Post by **Juande** » Fri Oct 26, 2007 9:33 am

Hi Bert

Thanks for your quick reply.

Sorry the missunderstanding. The visonic version I have is the 433.92MHz version.

What are the sizes for that version to build the antenna?

Thanks again!

Regards

Juande

Post by **b_weijenberg** » Fri Oct 26, 2007 9:48 am

The 433.92MHz antenna is described in detail in the document.