433 MHZ Antenna Design

[aquib]

I am trying to desing a Helical antenna for the 433MHz ISM band.
I want to make the antenna as small as possible, but want a performance close to that of a 1/4 wave.

Design techniques for the helical antenna is what I am looking for.

Cheers
Aquib

 

[Leftyretro]

I am trying to desing a Helical antenna for the 433MHz ISM band.
I want to make the antenna as small as possible, but want a performance close to that of a 1/4 wave.

Design techniques for the helical antenna is what I am looking for.

Cheers
Aquib

I would search the ham radio sites if I was you as 432mhz is a ham radio band and there are tons of antenna designs for their bands.

one example: **broken link removed**


Lefty

 

[JimB]

I but want a performance close to that of a 1/4 wave.

Then you need a 1/4 wave!
The performance of the helical is always worse than the straight 1/4 wave.

JimB

 

[Leftyretro]

Then you need a 1/4 wave!
The performance of the helical is always worse than the straight 1/4 wave.

JimB

I think I might have mistaken what is being asked for. It sounds like you guys are talking about a helical wound 1/4 vertical antenna, where I was referencing helical wound BEAM antennas which have very high gain relative to a 1/4 antennas.


Lefty

 

[Nigel Goodwin]

I think I might have mistaken what is being asked for. It sounds like you guys are talking about a helical wound 1/4 vertical antenna, where I was referencing helical wound BEAM antennas which have very high gain relative to a 1/4 antennas.

Yes, I think you were talking about completely the wrong type of aerial - but radio ham sites should have info on making what he wants, or at least the books should (ARRL or RSGB handbooks).

 

[RadioRon]

You want an axial mode helical. Here is a starting point:
https://www.dxzone.com/catalog/Antennas/Helical/

but this might be overwhelming. For some help, here is a handy helix calculator:

https://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=10523

and here is a cookbook version for one third your frequency so you would have to scale it up to 430MHz by multiplying dimenions by 144/430.

https://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=13537

 

[aquib]

Thanks guys for the suggestions. I looked at the site suggested by Leftyretro and found that it has the equations to design the antenna.
From what I understand that a helical antenna can be used in normal mode(as a DIPOLE) by designing its diameter much smaller than its wavelength.
I want to use the antenna for a telemetry based sensing project and space contraint is a big issue.

Cheers
Aquib

 

[JimB]

Yes, we had a normal mode helix in mind.

So, what do you REALLY want?
An antenna the size of a 1/4 wave, or one with large gain? It is not clear from your posts.

If you want a large gain, you need something bigger than a 1/4 wave.
An axial mode helix or a yagi with significant gain, will be (much) bigger than a 1/4 wave.

JimB