Why do we have to use dielectric material on microstrip antennas?

Hi

As far as I know all materials have dielectric constants, so......

Hello;
I think that microstrip concept needs a dielectric substrate for implementation; that is without use of dielectric substrate you can't refer your circuit as microstrip.

Hi:
as "no one" written , utilizing the substrate help us to fabricate microstrip network and antenna by Printed Integrated Circuit technology as "Microwave Integrated Circuit".

Because the substrate carry mechanicaly the resonant p@tch (conductor). As lower is the substrate permittivity as wider is the antenna bandwidth (wanted)

Other reason is to use dielectric is to decrease antenna size (wavelent is denominated with the square root of the relative permittivity)

Third reason is to simplify the feeding tract. Microstrip line feeds are imposible to create without dielectric. If you have probe feed, you are not obligate to use dielectric layer.

You should look around a little more. Most antennas do not use a dielectric substrate at all. Horns, dipoles, yagi, whip, loops, etc do not need a dielectric--only metal.