Re: Microstrip antenna
You can imagine a microstrip antenna just a simple two side PCB.
One side is almost out etched, only small portion in form of rectangle
or circular (and so on), so you get rectangular/circular microstrip antenna.
The dimension of the form must be chosen, so that the antenna work
effectively as a radiator. Also the thickness of the material of the PCB and
its dielectric charateristics.
The advantages of microstrip antennas are:
robust, low profile, you can attach it whereever you want, especially
you can hide it.
you can produce in mass with small intolerances. It becomes cheap.
The disadvantages are:
less directive (you must combine several antennas/array to get high gain),
low power antennas, and last but not least
microstrip antennas (and its derivative) probably, the most complicated
form of antenna to be analyzed
There are many good references on microstrip antennas :
Gupta K.C, Pozar, Hall etc
regards