New design approach of antennas with integrated coupled resonator filters

In the majority of microwave receiving and transmitting systems, a requirement is to have a filter immediately adjacent to the antenna or antenna array. This thesis presents a new methodology for antenna design where a filter is either fully or partially integrated with the antenna elements. The design of this antenna-filter follows the well-established coupled-resonator filter design theory, in which each resonator can not only be used as a filter element but also as a radiator. In order to verify the concept, a two-port bandpass filter designed using dipole antennas is the first work in this thesis to verify the use of dipole antennas as resonators. The coupling matrix has been used to obtain the filter response. One port antenna-filters made out of one, two and three dipoles. The method has also been utilised to implement X-band waveguide components which consist of an antenna-filter, antenna power divider and an antenna-diplexer. The calculation, simulation and measurement results are in good agreement. These proposed components has been designed, simulated, fabricated and measured. They have provided verification of the method, showing the antenna and filter theories and can be applied to miniaturise these components for use in the wireless communication and radar systems

UWB Bandpass Filter with Improved Rejection Band Performance Using Defected Ground Structure and Slotted Step Impedance Resonator

This paper presents an ultra-wideband (UWB) bandpass filter witb high performances for sharp rejection bands and wide stopband. The filter is designed with the combination of defected ground structure (DGS) and slotted step impedance resonator (SSIR). Two transmission zeros for controlling the stop band can be generated designing with tbe defected ground structure utili7.ed as a stop band resonator. Also its structure can be designed for improving the sharp rejection band. The wider upper stopbands caused by slotted resonator characteristics have also been obtained. The simulated and experimented results esbibited in good agreement and high sharpened rejection stopbands shown at 2.90 GHz and 11.50 GHz. High stopband performances are better tban 15 dB in tbe frequency range up to 18 GHz

Selective Six-Pole Microstrip Bandpass Filters for 4G Applications

Six-pole microstrip bandpass filters composed of square C-shaped resonators are designed for 4G applications at 2.6 GHz. To improve the filters selectivity around the passband, two pairs of transmission zeros are introduced by coupling of multiple resonators. The filters, which have different topologies, contain two cross couplings of opposite types in order to obtain a very sharp skirt. The simulation and measurement results show very good reflection and transmission characteristics. The proposed filters are synthesized using AWR® and simulated using CST® simulation tools. The simulated reflection coefficients are better than -13dB whereas the simulated transmission coefficients are better than -1 dB. In order to validate the simulations, one filter has been manufactured and measured. The simulated and measured results are in good agreement. The measured reflection and transmission coefficients are better than -12 dB and -4 dB respectively. The simulated and measured 3dB bandwidths are 80MHz and 60MHz respectively. A small shift in the centre frequency is obtained which is attributed to mechanical tolerances and tolerances of the thickness and dielectric constant of the substrate used