Electrically Tunable Antenna Design Procedure for Mobile Applications

Using a high-efficiency tunable antenna to cover a large bandwidth with low return loss is an interesting topic, especially in the case when the physical sizes of the mobile phone and antenna are too small to allow for the coverage of the full band. The limitations of tunable antennas are their losses and the nonlinearity introduced by the tuning devices. A design procedure for the tunable mobile antennas is presented, which accounts for the nonlinearity suppression. Following this procedure, a low-loss tunable digital video broadcasting-handheld (DVB-H) antenna has been designed and fabricated to cover the DVB-H band (470-702 MHz) with a return loss below 7 dB. This antenna exhibits a small volume of only 6 cm3. Despite the high-power signal from the extended global system for mobile communication transmitter on the same printed circuit board and the nonlinear tuning devices, this antenna is highly linear.