There is a special class of antennas known as planar antennas. Sometimes these are called microstrip or patch antennas. The key feature of these is that they can conform to a flat plane, or even a curved plane. This is a fascinating realm of antenna design.

Say you wanted to design a durable antenna that is small and can conform to the cylindrical body of a mortar shell, and report telemetry back to the base.

You want to design a patch antenna!

The most critical design parameter for patch antennas is called relative dielectric permittivity, given like e sub r here, often called keff.

The material between your ground and antenna affects the end result greatly! Common types of filling are silica and teflon fibreglass.

Head on over to microwaves101 if you want to learn more!