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Hi,

I'm having some reception/transmitting problems with my RFXTRX433, and looking to replace its antenna;

I found this one:

uk.rs-online.com/web/p/rfid-antennas/79 ... 3433353426

I know that there are many factors involved but should I expect improvements using such an antenna over the stock one?

Best,

Gustavo Melo

I guess it will not much improve the range.
This one is a better option http://www.conrad.com/ce/en/product/190 ... -Radio-Kit

Notes:
Place an antenna away from RF noise sources (a RaspberryPI for example is a device that produces RF noise) and from metal objects.
A switch board is not an ideal location.

See also chapter 2.5 in the RFXtrx User Guide

Hi,

I'm currently using a wi-fi antenna I had lying around (tp-link.com/en/products/details/?model= ... L-ANT2408C which, I guess, is totally inappropriate for 433 but, still, gives me considerably more range than the stock one...

I don't need a great range (~18 meters at most), I live in a 120sqm apartment; trouble is I'm trying to control dio / chacon plugs which are either a) close to each other B) inside cabinets.

I read a lot of posts regarding that antenna, and your recommendation, but I really would like to avoid it since I don't have a spot to hide it.

Question is: if a wi-fi antenna, designed for a completely different frequency makes such a positive difference, shouldn't a proper one, designed for the correct, 433, frequency solve my problem?

Best,

Gustavo Melo

Many options: domoticz.com/forum/viewtopic.php?f=4&am ... amp;t=2152

yep, already read those... problem is, I really need a more stealth solution, I don't have a place to put such an antenna...

I'm also interested in this.
Don't want such a bulky antenna

kriz83 wrote:.
Don't want such a bulky antenna

Nothing much you can do about that. These antenna's work optium when multiple pieces of conductor at a quarter length of the frequency wave length are used. So thats a dipole, consisting of 2x 17cm , or a ground plane of 4x17 cm with a monople of 17cm.

Nice (technical) explanantion: electronicdesign.com/wireless/what-s-di ... ne-antenna

Well, I decided to buy the antenna I mention in the first post anyway...

All my reception/transmitting problems are gone, and I can even receive a WT450H that couldn't before, but...

I can't honestly say this is solely because of the antenna, because I have the new one mounted in a completely different place, on a wall, 2,5m high.
But since it has a cable, I was able to put it where I always wanted to, so it was worth it. It's not exactly cheap - ~40€ delivered to Portugal, but it did solve my problems.
Maybe a cheaper antenna in the same place would give me the same results, but now it's done

I still believe that the raspberry pi has power issues with the RFXtrx433 because using the rfxmngr on my windows laptop gives me much better reception.

b_weijenberg wrote:I guess it will not much improve the range.
This one is a better option http://www.conrad.com/ce/en/product/190 ... -Radio-Kit

Notes:
Place an antenna away from RF noise sources (a RaspberryPI for example is a device that produces RF noise) and from metal objects.
A switch board is not an ideal location.

See also chapter 2.5 in the RFXtrx User Guide

Bert, what kind off connector do I have to order to connect this antenna to the RFXtrx433?

the antenna cable should have a SMA male connector.

This antenna can also be used:
http://www.ebay.nl/itm/GSM-GPRS-Antenna ... 5d5c986c75

Mounting another antenna would improve the reception and transmission, but you should not use another antenna that is not tuned on frequency.
Why ? , well, there is something called as SWR ( for more info read here:https://en.wikipedia.org/wiki/Standing_wave_ratio )
In short, if the SWR is not corresponding the frequency you want to use to Transmit, this can cause damage to the transistor.

For reception only this does not matter, but if you also want to transmit with the unit, the antenne should be the right length and tuned on freq.

Also, using a coax cable to get more length .
The higher you go in frequency the bigger the cable losses are.
With the cheap thin cables the loss is even higher, so keep the cable as short as possible.
Or use a good low loss cable, what can happen is if the signal is for example 10Db, and the cable has 9Db loss.
Only 1 Db comes in the receiver and the use of the bigger antenna is done for nothing.

Hope its all clear

And please correct me if you think im wrong, but this is just one of my other hobbies that i am doing for some years now, talking with people around the world by a radio and a antenna.

any 50ohm 433MHz antenna can be connected to the RFXtrx433(E)

73's PA3DEG