Diversity antennas for portable telephones

The design of high-performance built-in diversity antennas are described for two types of portable telephones: over-the-shoulder and handheld type telephones. First, the fundamental characteristics of a planar inverted-F antenna (PIFA) are presented. This type of antenna was chosen as the diversity antenna element for its compactness. The diversity antennas for the over-the-shoulder telephone are described. Location optimization yields an average correlation coefficient of 0.25 and an average gain of -2.9 dBd in carrying. Next, the diversity antennas for the handheld telephone are presented. Experimental results show that even a 0.1-wavelength separation provides an average correlation coefficient of less than 0.5. The PIFA element location is also optimized to give an average gain of -6.8 dBd in speaking