Wireless communication systems are important in modern day life. Applications of wireless communication systems are used everywhere around the world, such as cell phones, wireless entertainments, satellites and navigation services. Because of the high volume usage of various wireless signals' spectra, it is desired to design systems that can accept the frequencies of multiple signals. A combination of antenna and diplexers can achieve such functionality. With antennas operating in dual frequency and diplexers which separate the signals, dual-frequency signals can be effectively transferred through the wireless communication systems simultaneously.
In this thesis, we simulate and characterize the behavior of antenna and diplexer functioning in dual frequency. For the antenna, a mathematical analysis and a circuit model analysis were conducted to replicate its behavior. On the other hand, several circuit designs and simulations have been performed for diplexers. Moreover, an initial implementation of a single-order diplexer is also discussed. After the measurement, we found reasonable results for the functionality of a single-order diplexer. We believe that this first step gives us a correct route to our final implementation goal.
In the future, more implementation tasks can also be discussed. In addition to the implementation of a first-order diplexer, higher-order diplexers constructed on printed circuited board (PCB) can also be developed. Moreover, an implementation of a combinational matching network construction between antenna and diplexer can also be discussed
