wireless antenna for 433mhz

Vroom

Member
The 433Mhz that antenna of wire is 17.3cm for tx and rx both, make cut wire is correct 17.3cm not bit less or more, correctly 17.3cm is so great range right? what can increase or less than 17.3cm so will poor signal cause make short range?

Rubber Duck with SMA for HopeRF, that antenna of wire made a coiled 17.3cm for 433Mhz only so great long range?
 

BeanieBots

Moderator
The best thing is use STRAIGHT length. "Rubber Duck" is only a convienient way of making it smaller. It REDUCES range.
Get the length as close to ideal as possible for maximum range.

There are many different types of aerial design.
If you want extra range at the expense of being directional then consider YAGI. Others will give good pointers to home-brew aerial designs.
 

Vroom

Member
Thankyou for inform me, that use STRAIGHT length is best than normally wire bend cause poor signal?
lenght must stay correctly 173mm only is maximum range than 30-35cm?

Yeah, Yagi antenna can make longest range several kilometres as 4-5 kms so amazing.

What about rubber antenna 5dB from AV or network computer(2.4Ghz) what possible use rubber antenna for 433Mhz or not good?
 

manuka

Senior Member
Vroom: PLEASE forget using 2.4GHz items, as this frequency has of course a totally different wavelength & you may damage your gear with SWR mismatching. I suggest you read up about practical antenna theory & how it relates to the signal wavelength.

Most simple antenna are ¼ wavelength of the frequency in use. The terms are related by C= freq x wavelength ( with C = speed of light = 3 x 10^8 m/sec) Hence 100MHz will have wavelength 3m & ¼ wavelength will be 750mm, & 1GHz will need only 75 mm etc

433 MHz has wavelength ~700mm, & a ¼ wave whip (of length ~173mm) is THE simplest antenna- although it's radiation pattern will be omnidirectional. There are numerous other suitable types at this frequency, such as my simple 6dB "cotanga" Yagi -able to double range => www.picaxe.orconhosting.net.nz/yagi433.jpg.

GOOGLE both for 433 MHz & 70 cm (the near by UHF ham band) antenna/aerial as well.
 

Vroom

Member
wireless length

Thankyou, now Im understanding your inform, I believe 173mm is best for 433Mhz, realized forget about antenna 2.4ghz.
 

moxhamj

New Member
Yes, 173mm piece of straight wire. Those rubber antennas for 2.4Ghz look really neat, but I pulled one apart and all it had inside was a bit of wire of the correct length for 2.4Ghz.

433Mhz happens to be near Ham radio frequencies, so there are a huge number of antenna designs out there.

I have built some of these in the past http://commfaculty.fullerton.edu/woverbeck/quagi.htm and they certainly boost the range a lot.

But stick with 1/4 wave bits of wire for the moment and get that working and then you can move on to fancy antennas.
 

Zizka

New Member
Fascinating things, aerials.

At 433MHz a whip/monopole is theoretically 173mm long if mounted in the centre of a perfect groundplane.

In reality it's likely to be a tiny bit different. If you've got time it's worth doing range trials for a range of lengths down to about 16cm. (I normally guess about 16.7cm)

If your device has no groundplane, then performance can be a way off. In this case a helical ('rubber duck') can actually be better. (it's less groundplane dependant)

Or you can buy a decent part for under £5.

Try looking in Farnell for Phycomp 433MHz ceramic parts (there is a nice 12mm x 4mm part on 433MHz) or RadioSolutions M4 screw-stud mounted helicals.
Also look at the AF (Antenna factor, or Linx) parts in the Digi-Key catalogue for connector 'rubber' helicals, pre-wound wire 'exposed spring' helicals, and 'splach' (tm) planar types.

Interestingly, some simpler TV type Yagi aerials have a bandwidth that includes 433MHz, but only use these on the RX end, or you'll exceed the ERP spec. limit

Have fun

Myk
 

Vroom

Member
Zizka-t's very interesting to hear it, thank for amazing inform. I have had read through websites of Farnell about Phycomp 433MHz ceramic parts (there is a nice 12mm x 4mm part on 433MHz) that look so amazing smallest antenna, that great range like normal wire antenna?
 

moxhamj

New Member
Compact antennas certainly work but they do have less range. Essentially, an antenna needs lots of free space around it. High in the air etc. If you are going to put it several metres in the air like your TV antenna, you may as well use straight wire. If you are going compact so it fits in a box, by definition it will be closer to other components. Anything metal near an antenna is bad - metal, moisture - in fact anything conductive, will soak up RF energy.

Buy a few types of antennas and do some range tests.
 

boriz

Senior Member
I know very little about antenna’s and radio. Would a dipole be better? Would that be two 173mm wires? What does the gap between the wires need to be? Does that eliminate the need for a ground-plane?
 

moxhamj

New Member
Good question. I've used another 173mm piece of wire, joined to the earth, and heading off in the opposite direction. This is a dipole. The gap is only 1-2mm because there usually seems to be an gnd very close to the antenna. Sometimes there is even a hole for soldering. Maybe this is there for this very purpose. I think it works better. Never tested it completely scientifically though.
 

manuka

Senior Member
It's called a centre fed half wave dipole - of total antenna width ½ a wavelength. Hence a 100 MHz ½ wave dipole would be 3x10^8 / 1x10^8 = ½ of 3m = 1.5m across. Many other factors arise- impedance matching, radiation pattern, day/night coverage ( important on SW bands), polarity (H/V), & of course such practical issues as the ease of erecting a single tower rather than 2 side supports.

Although essentially simple enough, RF antennas encompass a vast field- it's akin to someone asking for insights on the workings of the opposite sex.
 
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boriz

Senior Member
Ha. That reminds me of an old joke. For those who have not heard it…

A pious man is rewarded by god.
“I WILL REWARD YOU WITH ONE GIFT, ANYTHING YOU WANT.”
“I’d like an 8-lane super highway across the Atlantic please.”
“YOUR JOKING RIGHT? NO, REALLY, WHAT DO YOU WANT?”
“Hmm, ok, I’d like to understand women.”
…after a pause…
“OK, HOW MANY LANES DID YOU SAY?”

:)
 

Vroom

Member
maximum range antenna for 433mhz

Whip antenna length is normally 173mm for 433Mhz, but many different some length, which best 150mm or 160mm or 167mm or 170mm or 173mm? I haven't test for 150m and 160mm and 167mm range yet, i will test with them which best length for long range. I believe 167mm is longest range.

Andy
 

westaust55

Moderator
antenna for 433mhz

Vroom,

please go back and read the earlier posts to you in the thread - even your own post No 5.

for 433MHz frequency using a ¼ wave whip the ideal length is ~173mm as a straight length . Not more and not less.

Shorter or longer will still work but if it is not an exact ¼ wavlength the antenna impedance changes and you do not transmit the maximum power. :eek:
 

Dippy

Moderator
Are we still trimming our antenna after 4 months? Lordy, you must work for the Government :)

What does the manufacturer's Data Sheet say?

If your RF Module is on a PCB then the tracks will contribute towards the antenna length though there are track techniques when using D/s PCB especially for RF when taking connections to antenna or coax connectors.

Absorb what Zizka has said. He probably knows more about nitty-gritty RF than anyone else here.
(Apologies to experienced Hams).
 

slimplynth

Senior Member
Am I the only person who is worried that men in grey suits will call round everytime they switch on their remote temp sensing etc?:D

Go for full spectrum domination, reach for the skies.. mount a tx/rx pair on a suitabley sized box kite.. that should do the trick. (i'm obviously joking - but curious as to how effective that could be.) My neighbour did this to take aerial pictures in the 70's.. the results were brilliant.
 
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Dippy

Moderator
Um, if you mount the Tx and Rx pair on your box kite how do you pick up anything on the ground? (assuming the box kite is flying of course :))

If you're curious why don't you try it?

I can see this thread going into Monty Python mode rapidly.

I prefer the idea of an Airship myself. With GPS, so it can come home when the wind blows it away.
 

slimplynth

Senior Member
i thought have a tx/rx pair so you can distribute what ever it is over a broad area with LOS to several locations.. and no I won't be letting curiosity get the better of me, as previous post I'm scared of the grey suits (puts tinfoil around his picaxe box and head) :D My Norwegian Blue Parrot modules have unlimited range.
 
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