Thermal Strain Measurements of Solder Joints in Second Level Interconnections Using Moire Interferometry

A low-profile UHF antenna comprises two orthogonally positioned parallel plate radiators that are semi-circular in shape. The base of each radiator (filled with dielectric material) is connected to a circular metal ground plane. The radiators can be collectively excited with a single input feed or they can be independently excited in any phase relationship for changing direction or polarization of the radiation field. Thus, the antenna is capable of operating in either a linear or circular polarization mode. The antenna can also be switched rapidly from one linear polarization to a second linear polarization in a perpendicular plane by using techniques familiar to the art.