Inverted F antenna - short circuit line

Hi, I am currently designing an IFA for 865-867 MHz. I would like to get a clear explanation regarding the following question

Why do we use a short circuit line to the ground plane?

Hi,

The respons is simple because a IFA is in fact a slot line with a lenght of lambda/2 (dual of a wire dipole). This slot is ,cut in half to give in one side an open circuit and in the other side a "short circuit". Electric Field is maximum at the open end and nul at the short end. The feeder is between the short and the open to give "50 ohms" usually.

Bye.

The answer to your question: Why do we use a short circuit line to the ground plane? is: For proper impedance matching.

IFA is a variant of ILA (Inverted L Antenna) which has an L shape and don't use this short transmission line for "proper" impedance matching as IFA.
ILA gets the right port impedance changing the length and the shape above the ground plane, characteristics which also in IFA are important.

I suggest that you see this link, its really well explained.
http://www.antenna-theory.com/antennas/patches/pifa.php