Tunable Antenna Design Procedure and Harmonics Suppression Methods of the Tunable DVB-H Antenna for Mobile Applications

Using a high-efficiency tunable antenna to cover wide band with good match is an interesting topic, especially in the case when the physical size of the terminal and the antenna is too small to allow for coverage of the full band. A design procedure for tunable mobile antennas is presented. A tunable antenna with the volume of only 6 cm³ has been designed and fabricated to cover the DVB-H band (470 MHz to 702 MHz) with a return loss of at least 7 dB. A limitation of the tunable DVB-H antenna is its non-linear behavior when it is recquired to coexist with the GSM transmitter in the same mobile phone. The harmonics generation and radiation is the most critical issue. Low-loss methods to suppress the harmonics are presented and the second tunable prototype DVB-H antenna shows excellent linearity.