[uncle_bob]

According to info from uncle bob, the problem was solved, just by resoldering the central antenna wire through the hole in the TX module. This info may help others.

Yes, this is true.
Thanks for the help on this one too.

[hvalentim]

Here (see attached pic.s) are the insides of a "433MHz GSM GPRS RP-SMA male Tilt-Swivel 20cm radio Antenna"

Comes with a 6,5 cm (7mm diameter) metal cylinder from which an helical (~1,5 cm visible) and a piece of very thin straight wire (~6,5cm visible) protrude. Unfortunately it is not evident how far these two eventually go inside the tube.

Should the straight wire go down to the base, it must have around 17 cm, which would be the correct length.

   
   
   

[werk_ag]

These are my prefered for RX.

This is just my opinion, based only on practical results, I don't have dedicated equipment of knowledge to do more specific tests (Gain, SWR, etc).
Let's see if Meteoestarreja has something to say about it.

[meteoestarreja]

Good morning all

First of all, I'm sorry about some missing answers ... If only days had 24 hours and nights another 24 ...

The measures looks promising. The inner wire looks right having the right measure and I'm thinking in two possibilities for the outside element, or is a complement from the wire making this a funny designed antenna or is what we spoken before - a ground plane ...
Either way, looks that this antenna is not that chinese mumbo jumbo antennas with lot of plastic and almost nothing on the inside, I'm guessing that this would be a "real deal".
Better than this is like Werk_AG says, testing with instruments ...
Maybe we should open an testing lab just for this and accept samples to test, any volunteers?

As I said here, these are my prefered for TX. I'm using one in each of my two TX units.

This is just my opinion, based only on practical results, I don't have dedicated equipment of knowledge to do more specific tests (Gain, SWR, etc).
Let's see if Meteoestarreja has something to say about it.

[hvalentim]

Well, at 5 meters you almost don't need an antenna (just kidding)

Actually that is confirmed to be true. I can get the TX unit to be properly received without any sort of TX antenna, not even a wire, up to 15 meters away (with a house in between).

I can the signal at least (did not test further away) 25 meters away just by placing (without any solder) a piece of ~17cm AWG22 wire over the TX module antenna hole.

So in practice an antenna on the TX side is optional. At least for me.

[werk_ag]

So in practice an antenna on the TX side is optional. At least for me.

I know that we are using a very powerful TX module with more than 10 mW transmiting power, but I strongly recommend to everyone to install an antenna in the TX module.
Your conclusion may be somewhat precipitated. Do you already have an anemometer connected to the TX unit? The wind data packets are sent every 5 seconds, I think you will don't want to lose to many data packets.
If the place of your installation is almost free of outside RF interferences at least install a simple coil antenna like this one below.

[hvalentim]

Your conclusion may be somewhat precipitated. Do you already have an anemometer connected to the TX unit?

Not yet. No anemometer used. Just temp/hum and solar radiation.

at least install a simple coil antenna like this one below.

Of course. I will install a proper antenna regardless. I was just commenting the fact that meteoestareja's joke may prove real. If it worked 15 meters away with a few walls in between there is a chance it may work at 5 meters with far less obstacles in the way. I will let you know the result when I test that way with the anemometer connected.

[werk_ag]

A simple 16.5cm wire can make a good antenna, maybe even better than the coil antenna shown above. What I don't recommend is, not have any antenna at all.

[meteoestarreja]

What I don't recommend is, not have any antenna at all.

That's a principle to take in account in every radio transmition equipment.
Because without an antenna you will have problems with standing wave ratio especially with higher radio output power - that's not the case with those small TX module, anyway, I would say that an antenna is kind of mandatory ...

[hvalentim]

I have soldered a piece of RG-174 cable (around 40cm) to the TX Module, fitted in the 20 cm antenna described above, plugged the TX unit to my car 12v supply and did some testing around the neighborhood.

With the TX unit inside the vehicle and the RX inside my office the best result achieved was 60 meters.

For even better results I guess one could try RG-58 cable and say half the lenght (20 cm).