Research Of Microwave Filter And Antenna

The demand for multi-bands,ultra wideband,miniaturized and more flexible microwave passive devices is growing.It has xwide application prospect in various wireless communication systems.Among all kinds of microwave passive devices,microwave filters and antennas occupy a large proportion,which has a very important role in the wireless communication system.Miniaturization,integration is the main trend of the development of communication systems in the future.Therefore,the design and implementation of a variety of new microwave filters and antennas and realizing microwave devices in multi-band and ultra wideband applictions has very important engineering significance.It is an important research direction of modern microwave passive devices.In this paper,the realization form and design method of multi-band and ultra-wideband microwave filters and antennas are studied.The main results are as follows:1.Research on microstrip dual band filter based on slot structure.A single patch resonator with right crossed slots and rectangular perturbation is proposed to design a dual-mode dual-band bandpass filter.The compact design has a flexibly controlled first passband and a fixed second passband.The first resonance varies with the width and length change of the slots,but the second resonance is not perturbed because of the right crossed slots.The proposed dual-mode dual-band filer operating at 1.57 and 5.2GHz for GPS and WLAN application.This greatly increases the application flexibility of the dual band filer.2.A dual-mode dual-band bandpass filter with novel perturbation element using open loop resonator is proposed.A couple of open stubs are placed in each inner corner points of the square loop resonator.The designed filter using a novel perturbation arrangement without extra perturbation elements is different from the other dual-mode dual-band filter configurations.The two degenerate modes are excited by the movement of gaps between the open stubs.The new type of perturbation structure enriched the realization form of dual mode filter.3.A novel ultra-wideband bandpss filter using a modified multiple-mode resonator is proposed.The resonant frequencies of this MMR in the design are properly adjusted equally within the ultra-wideband passband.The 3 dB passband covers the range of 2.5-11.1 GHz,and the fractional bandwidth is 126%.The circuit size of the proposed filter is extremely compact which amounts to only 0.58 ?0×0.12?0,where ?0 is the guided wavelength on the substrate at the midband frequency,realizing the miniaturization of ultra-wideband filter.4.Two kinds of novel ultra-wideband filters with notched bands are proposed.Firstly,an ultra-wideband filter based on ring resonator is designed.Through embedding open circuited stub with different lengths in the traditional coupling feed line structure,a notched band and transmission zero in high frequency can be generated without extra circuit size.Finally,in order to generate multiple notched bands in ultra-wideband passband,asymmetric dual-line coupling structure is applied to the feed line,resulting in triple notched bands obtained in ultra-wideband passband.5.A simple triple band metamaterial-loaded small planar monopole antenna is proposed.In addition to the regular monopole resonance,two inverted L-shaped slots on the monopole patch are introduced to realize two other resonances.The metamaterial loading is then used to expand the lower resonant frequency.The proposed monopole antenna can operate at two narrow bandsand one wide band.The frequency bands can be flexibly adjusted,covering a plurality of mobile communication frequency bands.