Antenna Strength

Post by **Kroonen** » Sun Feb 08, 2009 11:57 am

Hi,

I got an older rfxcom reciever, with an (spriet) antenna.

To recieve te signals from outside near the garage and from the garage, I sometimes get nothing(see image, the signal is the same). So it looks like that it can reach almost, mut not stable. Is there a way to boost the signal a little bit?? Or are there stronger antenna's? (the new ones?)

Post by **Snelvuur** » Sun Feb 08, 2009 1:51 pm

I think bert mentioned a method for this, but i cant seem to search it 1.2.3.

// Erik (binkey.nl)

Post by **b_weijenberg** » Sun Feb 08, 2009 2:13 pm

The source of the problem can be the receiving signal strength or multiple Oregon sensors of the same model (TH1,TH2 etc) set to the same channel.

Received signal strength:
1. Position the receiver antenna to get the optimum signal strength of all sensors.
2. Use a broadband TV antenna signal amplifier.

Multiple oregon sensors:
See 10th entry in http://www.domoticaforum.eu/topic.asp?TOPIC_ID=1353

Post by **Kroonen** » Sun Feb 08, 2009 7:21 pm

It's not the oregon channels. The outisde i already put on 1 channel where the rest is not on it.

I will try an antenne amplifier.

Is any antenna amlifier ok for this?

Post by **b_weijenberg** » Sun Feb 08, 2009 9:26 pm

as long as the amplifier will cover 433.92MHz

Post by **binkiem** » Fri Mar 27, 2009 11:19 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by b_weijenberg
 as long as the amplifier will cover 433.92MHz
<hr height="1" noshade id="quote"></blockquote id="quote">

i have a new version of the receiver. Do you have some setup which has been approved? What type of amplifier is suggested. Are there any restrictions about the connection between antenne, amplifier and RFXCOM receiver. Are cables allowed and what are the minimum and maximum lengths?

Post by **Stevexyz** » Sat Mar 28, 2009 5:43 pm

If the transmitter is almost in range another idea is a "passive repeater". This is just a length of stiff wire about 34.5cm (for 433.92MHz) placed behind the sensor. It catches the part of the RF signal that's going in the wrong direction and reflects it towards the receiver. You might have to play a little with the orientation. I use one for an outside X10 motion sensor which has to transmit upwards and through two brick walls.

Here a good description http://davehouston.net/passive.htm although the measurements are for 310MHz. 34.5cm is about right for 433Mhz.

Post by **binkiem** » Sat Mar 28, 2009 10:39 pm

The Oregon sensor who has the most problem is situated in the bathroom. It is difficult to add a passive repeater because i think i get some problem with my wife [:D]

I prefer some active amplifier. I hope someone post an proven example.

Post by **RdP** » Sun Oct 11, 2009 6:17 pm

Does anyone has good experiences with boosting the receiving of RF signals off (far away) sensors. I'm having problem with a number of outside sensors.
I have a USB RFXCOM receiver.

Many thanks in advance,

Post by **Menno** » Sun Oct 11, 2009 6:22 pm

I am using a antenna signal amplifier that is normally used in CAI systems.

This works great for me. Now i am able to receive MS13 and other 433,92 MHz transmitters with my RFXcom receiver.

my amplifier:

Post by **drmacchi** » Sun Oct 11, 2009 8:20 pm

Menno, please could you type model and producer ? thanks. lorenzo

Post by **DutchAdept** » Sun Oct 11, 2009 8:42 pm

This is a Konig (Koenig) CAI amplifier, either the 20db or 30db version (both models look the same).

In/Out: 1/1
Accomodates Return Signal

Frequency Range: 86-862 MHz
Amplification: 20/30 dB
Attuning: 0~18 dB
Amplification Return Signal: 2~20 dB
Adjustable Slope: 0~18 dB
Noise: max. 7 dB

Cheers,

Alex

Post by **RdP** » Sun Nov 01, 2009 2:42 pm

I still can't get it right !! I tried a antenna signal amplifier (hirschmann) which I used for my TV signal in the past, but then it gets even worse. I must say that I can't see how a antenna signal amplifier can get things better. I use a 2 meter cable between the antenna and my (usb)receiver. I the signal doesn't get picked up by the antenna, a signal receiver can't solve that. A 2 meter cable can't make the signal worse.

So I think my problem is that the antenna does not receive the signal at all. I have this my windmeter and a THGR228 most/all of the time and a UV128 and a PCR800 sometimes. This was good a couple of months ago, but for some reason the signal gets interfered.

Does anybody have some other good idea to solve this.

See photo of my antenna which is located in the equipment closet, about 15 to 20 meters form the sensors

Thanks,
Rien

Post by **DutchAdept** » Sun Nov 01, 2009 4:03 pm

Too much metal and wiring around the antenna kills the reception. As you stated yourself: if no signal is received at all then using an amplifier is useless. The photo shows metal pipes and wiring all around.... so that will surely not improve things.
Try placing your antenna at a metal free spot.
If you don't want to have a large antenna in sight I suggest using one of these: http://www.conrad.nl/goto.php?artikel=190060
For that antenna you can even make a sheet metal groundplane, and hide that in the wall (pics on request)
When using longer cables for your setup, use high grade coax like AirCell or AirCom (low insertion loss).

Also try to fnd out if you have collision/interference problems...
Have you recently installed metal objects near the antenna or near/in the path between the units and the antenna?
Did you add more RF units near the antenna, did your neighbour start domoticizing his house

or has there been any equipment installed recently with a large magnetic signature (like large electro motors and such)?

Post by **RdP** » Sun Nov 01, 2009 4:49 pm

Thanks,

I think I'll try the one you suggested. Are you using this one also ??

The antenna has always (for many years) where it is now and to my knowledge there are no new or changed RF units. THe only new equipment is my wireless Router, an Apple Time Machine. But this is operating in much higher frequencies.

/Rien