I. INTRODUCTION
The license-free frequency band (about 7 GHz) around
60 GHz on the one hand and the developments of electronics
and modern communication at higher frequencies on the
other hand make the 60 GHz band worldwide extremely
attractive for wireless communications. Antennas are key
elements in a wireless communication system and because of
short wavelength at 60 GHz they can be embedded in
package. Many efforts have been made to improve the
capabilities and feasibilities of an antenna concept in package
[1], [2].