Yagi antenna question

Hi all,

I'm searching for theory and/or tools for building a 433 MHz Yagi-Cuda antenna.
I understand the principle of Yagi-Cuda antenna, the use of parasitic elements to increase directivity, I found some informations about it, but without explanations why I should separate each element by this distance, nor this one.

And, by the way, a question: what is the consequence of putting dielectric, instead of simple air, between elements ? Will it change the gain of the antenna ?

I think my question could be answered by reading Yagi-Cuda antenna theory so, if you have technical information, this will be great !

Thanks a lot in advance !
Regards

First of all the name of the inventors of this antenna are Yagi and Uda.

The distance between elements is related to fractions of the wavelength (of resonant frequency), in this way reflecting or directing the radio waves in a particular direction.

A Yagi antenna always uses a dielectric between elements, whatever this dielectric is: air, epoxi, alumina, etc.

The Er of different dielectric materials will affect the resonant frequency of the driven element, and also the frequency bandwidth and beamwidth angle of the antenna.

Yagi Uda, Yagi Uda, Yagi Uda... that's what happened when you search for 2 different things, that are Cuda and antennas :D

Apologies !

Thanks vfone. By the way, do you have any paper related to this ?

Regards

Useful links for your studies:

http://en.wikipedia.org/wiki/Yagi_antenna
http://www.dxzone.com/catalog/Antennas/Yagi/

have a look at:
http://www.k7mem.150m.com/Electronic.../yagi_vhf.html

you will find theory/equations in the ARRL book.