simulation of rf fields (newbie)

[leonix]

Hi,
I want to integrate a 2.4GHz part inside a metallic case (imagine that it is a ring that is closed top and bottom, with the HF module inside).
But dont want a external antenna (there should be no external rod that one can break). Instead I want to add a non metallic ring or some holes, like this is done with waveguide antennas.
How can I calculate or simulate this? Is there a simple software available with that I (a newbe in the field of HF modelling) can simulate RF fields and antennas? (I only need 1-2 metres range with 4dBm at 2.4GHz).

thx

leonix

 

[vfone]

In my opinion, the best is to do a prototype. Put the radio in the box and see if you can get the connection.
At this frequency, and at this distance you can have a lot of parasitic resonance’s that can help you.

 

[leonix]

Yes this is true, but playing with the geometrics in a model would be much more effective than doing it blind in hardware. You could get a idea what to do and what to avoid. (experimenting with spice is also much better than bread boarding). Only some finetuning is needed then in hardware.

E.g. If I am near than 1/4 lambda to a wall I probably have a big attenuation.
Exactely 1/4 Lambda would be best I think, but how does other metallic parts influence this (and the other walls inside the ring).

Leo

 

[steveninvan]

Try NEC (Numeric Electromagnetic Code). I guess there are some old versions which are free. Just need to take some time to learn it. It is pretty good for analyzing antenna structures.

Go to <http://www.si-list.org/swindex2.html> to have a look.