عباس رضایی

Microstrip technology is widely applied for design and implementation of several communication devices such as filters, diplexers, triplexers, multiplexers, couplers, etc. They are utilized to isolate desired signals and remove disturbing signals. The layout of filters, diplexers and triplexers have two, three and four ports, respectively. Passive filters have at least one pass channel, whereas diplexers have at least two channels to transmit the desired signal, and multiplexers have more passbands with more channels. In order to implement the passive components, first a cell called resonator must be designed. Creativity is very important in resonator design. It must be small and novel to get a better device than previous works. Therefore, the layout of previous reported resonator, used in passive microstrip devices, are studied in this work. There is a fierce competition among designers to miniaturize and increase the device performance. Hence we will investigate them, from the point of view size and performance, in this work. Some diplexers are multi-channel, which are more difficult to design than two-channel diplexers. Therefore, the multi-channel diplexers are less reported than the two-channel diplexers. The design of multiplexers is also very difficult because several channels must be controlled. Hence, they are less designed than filters and diplexers. The diplexers can be bandpass-bandpass or lowpass-bandpass, where the latest is less designed. This is because designing a lowpass-bandpass diplexer needs lowpass and bandpass resonators, whereas the design of a bandpass-bandpass diplexer needs only a bandpass resonator.