Today mobile telephones almost become an indispensable part of our lives. Mobile telephones bring a lot of convenience to us. Mobile wireless communications develop very quickly. In the mobile communication, in the past decade, the industry has grown significantly. We all see that the mobile communication system is developing in rapid change. The change is shown in mobile handset antenna for example. Before 2000, most of the mobile handset''s antennas were visible on the phone, thus it was bulky sized and unattractive. From the mid of 2000, mobile handsets became more compact, attractive and thin, it all related to antenna design. The antenna design of the mobile handsets which we are using nowadays, they are designed separately for each frequency. This makes handset bulky.
Thus, This paper is proposed to design mobile handset antenna for make mobile handset more compact and thin. This antenna has an advantage of performing different frequency bands by one antenna design. For this purpose, a varactor diode is used in antenna design. Design and simulations are done using CST Microwave Studio program. A Reconfigurable Antenna is designed by using the FR-4 ( lossy ) substrate with the dielectric constant of er=4.3 and dielectric loss tangent 0.025. The substrate thickness of h=1.6[mm], length=L_sub, width=W_sub. The ground is designed by using the PEC material with h-0.035[mm] and length=3/L_sub. The patch designed by using the copper with h=0.035[mm], length=1/L_sub.
In a result, return loss was below (S|11|<-17[dB] at 0.8[GHz], S|11|<-[16dB] at 0.9[GHz] band.
An integrated Low Noise Amplifier which includes bias circuit and input/output matching was produced. A substrate size is about 2.7[cm]. A frequency bandwidth of the produced Low-Noise Amplifier is 800[MHz] to 1[GHz], gain is 20-21[dB], and noise ratio is less than 0.7[dB]. A measured S11 of the low loss is -17[dB], and S22 is less than -9.8[dB].
After we manufactured the Low-Noise Amplifier, we measured Channel1, Channel2 and Channel4 by the value of the measured data. We set and measure Channel1 by S11, Channel2 by S21
and Channel4 by S22. and the result of the measured range of 800 [MHz] to 1 [GHz].
In the future, this antenna design will be fabricated and used in a mobile handset systems.