(TIP) Increase reception RFXcom433

[ThinkPad]

Yes.

voorzien van flexibele draadantenne

Just do it yourself, very easy 5 min work.

[Hesmink]

Yes.

voorzien van flexibele draadantenne

Just do it yourself, very easy 5 min work.

I have this one, it's fairly obvious where the antenna is at:

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temp_inside.jpg (157.32 KiB) Viewed 8657 times

[ThinkPad]

I also have that one Should be really easy to mod them, just replace that coil by a 17cm wire.
Or stretch it and cut it at 17cm from the solderpoint.

But i don't have any issues regarding transmission range, so i'll leave it original.

[Heisenberg]

Although all the tips are great regarding modding devices by extending the antenna wire I'm still looking for an aesthetic solution for the RFXcom433(E). Because then you only have to mod the RFXcom433 instead of all the devices that don't receive signals properply .

Will an antenna with > 5dBi boost the signal? Like this one. Or is it useless and better to use a 3 or 5 dbi antenna?

[sincze]

Although all the tips are great regarding modding devices by extending the antenna wire I'm still looking for an aesthetic solution for the RFXcom433(E). Because then you only have to mod the RFXcom433 instead of all the devices that don't receive signals properply .

I couldn't agree more

[sincze]

I bought this antenna: http://www.ebay.com/itm/281126334307 and pulled the plastic off.
Then desoldered the standard coil, and attached a 17cm stiff wire of a networkcable to it like this:

IMG_20150808_131500.jpg

Drilled a small hole in the top of the plastic tube so the wire can go through it, pressed the plastic tube back on to the connector and ta-da! Works fine and will cost you little.

Just ordered the antenna, let's see and find out

[sincze]

Received the replacement antenna and soldered 17,3 cm stiff (installatiedraad) to the base.

Doesn't make that much difference compared to the one I already had installed That can be ordered for a few euros for example here:

http://www.ebay.com/itm/Radio-433Mhz-5D ... 0945866818

Suggestions anyone?

[sincze]

Switching a device over a longer distance can also be achieved via this device the IPIO-KAKU-2
http://www.webrelais.nl/IPIO+KAKU+2+v6.0+config.html

[Grobbebol]

I bought the 5dB antenna through AliExpress. It costs about 5 Euro and has free shipping to Europe.
Delivery time is about two weeks.

http://www.aliexpress.com/item/GSM-Ante ... 82918.html

For me its working fine, had some trouble with reception of a "hidden" On/OFF switch stacked away behind a cabinet.
Also the garden house is now under the cover of the Domoticz Raspberry.

[Hesmink]

Is the antenna also responsible for the transmit power?
I can receive everything now, but I cannot switch my kaku stuff trough a thick concrete wall.

An extra RFXcom is a bit expensive.

[Stokie21]

would this one be any good?

http://www.ebay.com/itm/433MHZ-35dBi-SM ... SwFdtX17Mq

[tjabas]

isnt there any 433mhz booster that can be used?
like from amateur radio, i guess that these could increase the output by watts instead of milliwatts.

i now that it isnt very leagal, but is it possible?

[sincze]

For my house the solution came with the RFLINK.

RFXCOM (old style with 10db gain antenna) for ground & first floor.
RFLINK (with 5 db gain antenna) for first and second floor.

Some devices are now detected... twice.. I don't really care about that. As long as I can switch and receive them.
The boxes RFLINL & RFXCOM are mounted out of sight and you only see the antennas sticking out over a closet or so. WAP 'ok' / 'approved'.

[Bernd]

The original antenna seems to be quite small actually, someone discovered: http://domoticz.com/forum/viewtopic.php?f=44&t=6772
So it is not a miracle that a other/longer one is working better.

That picture comes from me. I now have a vector impedance analyzer and measured several antennas.

868 MHz (LoRaWan):
I have 2 antenna's measured. Both are on spot with a VSWR around 1.5 for this frequency

433.92 MHz:
The RFXcom antenna gives a VSWR, worse than 6.0.
The center frequency, which is with the lowest VSWR, is around 478 MHz, so far away from what it should have been.

I also measured another 433.92 antenna, the one with the magnetic foot and a coil half way the antenna. This one was on spot with a VSWR of less than 1.5.

CONCLUSION
The delivered antenna with the RFXcom unit 433 and 433E is not the right one. Most RF-power is not being sent by the antenna
Bert, please comment.

VSWR is a measure of how much transmitted RF-power is being reflected back into the transmitter. A VSWR of 1 means that all RF-power is transmitted. That is what we want.
For reception, this is somewhat less important.

[freijn]

Would a simple Dipole be better and much easier to create ? 2 elements of 16.4 cm ?
if we put the dipole vertical instead of horizontal we have a circulair reception.

What do you think ?

[Bernd]

No, a dipole is a symmetrical antenna and the RFXcom only has a coaxial connector (asymmetrical). You can use a dipole but than you have to use a balun (short for BALancedUNbalanced) but this is rather complex for non-experienced people. A simple vertical wire of about 17 cm seems to give the best performance for transmitting the commands towards the switches.

Put the RFXcom somewhere high in the middle of your area to cover, not too close to a wall or other obstructions.

[DomoticaRob]

I bought this one:

1 st 433 mhz 35dbi high gain sucker antenne koperen bar 3 meter verlengkabel SMA MALE radio antenne #2

https://nl.aliexpress.com/item/433Mhz-3 ... 4c4d1bLRTk

Because my yard is 85 by 85 meters and I wanted full coverage. It works super and I got it in one and a half week.

[Dave21w]

I posted this a few weeks ago, to be honest I still haven't got around to building one yet for 433Mhz but I have made them for 2.4hz Wifi and they work really well.

You need each side of the square to be the same lenght as a 1/4 wave for 433Mhz, this is easy to work out. 300 divided by the frequency = a full wave, divide the answer by 4 and then multiply the result by 0.95 to take into consideration the velocity factor of RF through copper. Radio waves travel at the speed of light in air but passing through a solid slows them down slightly. If you want to be really accurate then use 433.92 (as that is nearer to 434 so it will alter the length slightly)

https://www.researchgate.net/figure/BIQ ... _308960731

What you need to remember is with a unity gain antenna (no gain) the effective radiation / reception pattern is a sphere with the antenna point being right in the middle so equal signal in all directions including up and down, as soon as you start to introduce gain to any antenna it starts to become directional so in the case of a vertical antenna the signal pattern starts to behave more like a donnut, the more gain the less signal top and bottom and the beam width from the side starts to narrow so if the the devices you are trying to connect to are a long way off they need to be roughly the same height as your antenna.

Hope this heps.

Dave

[Gerwin]

Is it possible to place 2 antennes on one rfxcom with a splitter en place one antenne in the front of the house and one in the back of the house.there is een smb splitter
Gerwin

[freijn]

The most honest answer is no you can't. Perhaps for reception it would work but for transmitting you loose a lot of signal.
Splitting requires an adjustment of the impedance of the cables. Not simply put them parralel. Also you will always loose signal.
Also running a long coax cable from one end to the other will also make you loose signal. Can't you put the reciever in the middle of the house?