Fundamental Research On Parallel Coupled Line Filter And UC-EBG Application In The Integration Of Muti-Antennas

With the rapid development of modern wireless systems, it put forward to higher requirement to the transceivers, the market competition increasingly fiercer and fiercer. Consequently, it demand the whole system more compact, high reliability and low cost. Antenna and filter are two essential components in modern communication system. Antenna provides instrumentality for radiation and reception of radio waves, the performance of antenna directly affects the quality of the communication system. Filter plays a major role of filtering out undesired frequencies and passing the desired signals. In response to this need, this thesis investigates the parallel coupled line filter and UC-EBG applied in the integration of multi-antennas. The contributions of this thesis are as follows:1. Presented a compact wideband high-rejection microstrip filter using two meandered parallel-coupled lines of different electrical lengths and characteristic impedances in shunt. The filters based on signal interference technology. A set of analytical formulas and guidelines for the design of the filter are provided in two theoretical analysis methods, one is even-and odd-mode analysis theory, the other is two ports analysis theory. The transmission zeros and reflection zeros of the filter can be controlled through the analytical equations and rulers given. Bandwidth and rejection level of the filters of this bandstop filter can be designed by choosing different even-and odd-mode characteristic impedances values of the coupled lines. To validated this topology, a wideband bandstop filter with a3dB cutoff frequency bandwidth of92%centered at2.6GHz with sharp rejection characteristics is built to verified the theoretical prediction, the measured frequency response of the filter agrees excellently with the predicted result. The structure can also for bandpass filter, to validated this topology, two wideband bandpass filters centered at3.0GHz are built to verify the theoretical prediction, the measured frequency response of the filter agrees excellently with the predicted result.2. Using coupled lines and open stub design T-type filters. The first part of the bandstop filter consists of two meandered parallel coupled lines and one open stub, the filter use a direct feed methods. Through analysis the frequency response with the open stub impendence and odd and even mode characteristic impendence change, select appropriate physical parameters, produce filter to very the design. In the second part, this paper proposes four T-type circuit structures formed by three sets of parallel-connected coupled-lines. The circuits could achieve bandstop or bandpass characteristics with slightly changes in the structure. Simulate the circuits use software ADS and HFSS. Based on the above analysis and discussion, a prototype filter was built on Rogers R04350B. Measured results of the four filters are the same as the simulation results indicating that the filter structures proposed in this study function well as expected.3. Putting forward a new type of resonator, and analysis of the mode of the resonator. Through weak coupling, we find in0-5GHz range, there are four resonator peaks, study the way for the first and second resonator peaks formed the first passband, the third and fourth one formed the second passband. Added an open stub at the bottom of the resonator, through suitable coupled method formed a dual-band filter. The experimental results concerning the fabricated filter measured by network analyzer agree well with the simulation results4. Design diploes of CPW-CPS fed worked at3.45GHz, and formed an3×2antenna arrays. Applied UC-EBG to the integration of multi-antennas arrays, study the mutual coupling between antennas. A wideband coplanar waveguide-to-coplanar strip balun was designed and used to transform the unbalanced CPW feed line to a balanced CPS feed line for the dipole antenna. Design the UC-EBG size bandgap at the3.45GHz position, used the UC-EBG structure for antenna reflector, also placed UC-EBG between the adjacent antennas, Mutual Coupling between Antenna Elements is investigated, through measured and computed the antenna correlation coefficient is blow0.7.