W. Y. Sam

Design of reconfigurable defected ground structure (DGS) for UWB application

This paper presents the design of reconfigurable defected ground structure (DGS) resonator that can be integrated with ultrawide-band (UWB) microwave filter to produce bandpass and bandstop response simultaneously. The reconfigurable DGS is designed based upon coplanar waveguide (CPW) technology to exhibit bandstop characteristic at 3.5 GHz and 5.5 GHz using FR-4 on a 1.6 mm dielectric substrate thick with dielectric constant εr = 4.6. The simulation performance shows promising results that could be further validated during the experimental works. This topology of reconfigurable DGS is useful for applications when the undesired signals need to be removed such as in wideband systems.

Rectangular microstrip patch antenna based on resonant circuit approach

This paper presents the investigation based upon the resonant circuit approach to characterize the rectangular microstrip patch antenna from the low-pass prototype lumped element. The physical layout of the rectangular microstrip patch antenna based on single-mode and dual-mode will be established. An improvement on bandwidth of the antenna can be achieved by increasing the number of modes. In the paper, the understanding of microwave filter synthesis technique is applied in order to obtain the resonance at 2 GHz. A notch technique is used in the design to produce dual-mode frequencies on the microstrip patch antenna. The prototype circuit and proposed physical layout of the single and dual-mode microstrip patch antennas are demonstrated through the analysis of circuit and EM simulations in order to proof the proposed concept. This study would be useful to realize antenna for broadband applications as well as to investigate the appropriate technique for integrating antenna and microwave filter.

Microwave filter and antenna for wireless communication systems

This paper presents the investigation and characterization of integrated microwave filter and antenna to reduce the overall physical volume for RF/ microwave front-end subsystems. This study focuses on the integrating of rectangular Substrate Integrated Waveguide (SIW) filter with rectangular microstrip patch antenna to produce filtering and radiating element in a single device. To proof the concept, the integrated microwave filter and antenna at center frequency of 2 GHz is demonstrated and validated through simulation and analysis. This class of microwave filters and antenna integration would be useful in microwave systems where the reduction of size and weight as well as cost is very important such as in base stations and multiplexer in any communication systems.

A Review on Reconfigurable Integrated Filter and Antenna

In the past few years, several satisfying various objectives and designs of reconfigurable integrated microwave filter and antenna have been proposed for wireless communication systems. Several designs are new concepts and techniques, whereas others are inspired from previous works. The improvement concepts of these designs can be reviewed from this compilation of studies. This paper begins with an explanation of the reconfigurable filter, reconfigurable antenna and reconfigurable integrated microwave filter and antenna, followed by discussion on several designs in terms of size, measurement, performance and technology used. Among various designs, reconfigurable on planar structures are extensively used because of their simple design procedures and easy to tune on the desired frequency, bandwidth and attenuation. Most of the existing studies are focusing tunable on single element, i.e. either on filter or antenna side; however, it limits the tunable range and flexibility of the filtering antenna response. An alternative design of filtering antenna can be suggested to produce reconfigurable tuning capabilities on both microwave filter and antenna to produce overall good performance for multifunction operation in RF/microwave applications.

Design of integrated rectangular SIW filter and microstrip patch antenna

This paper presents a new class of integrated rectangular Substrate Integrated Waveguide (SIW) filter and microstrip patch antenna for RF/microwave front-end subsystems. To validate this concept, the integrated microwave filter and antenna based upon a cascaded approach at center frequency of 2 GHz is demonstrated and verified through simulation and measurement. Experimental results show good agreement with simulated results. This study also proposes a new technique to integrate the rectangular SIW filter and the microstrip patch antenna based upon the multilayered approach. The simulation is implemented using FR-4 on a 1.6 mm dielectric substrate thick with dielectric constant εr= 4.6. The simulation performance shows promising results that could be further proved during the experimental works. This study is useful for any microwave system design where the reduction of overall physical volume and weight as well as cost is very important.

A compact DMS triple-band bandstop filter with U-slots for communication systems

This paper presents compact structure of bandstop filter with Defected Microstrip Structure (DMS) to produce a triple - band reject response. To prove the concept of the narrow notched DMS, the operating on centre frequency of 4.0 GHz is demonstrated and validated through simulation. The DMS structure is embedded in the middle of transmission lines in order to reject any undesired signals which may interfere with any communication systems. The design was simulated based on Roger Duroid RO4350B with a thickness of 0.508 mm and dielectric constant of 3.48. This type of filter is useful in any RF/ microwave communication systems, particularly to eliminate any undesired signals in wideband spectrum. While maintaining its excellent performance, the overall physical and cost reduction can also be achieved using this technique.

Intermodulation distortion of Integrated Power Amplifier and filter using single stub tuners for green communication

Integrated Power Amplifier (PA) and filter which is part of important component for Radio Frequency (RF) transmitter is designed using Adavance Design Simulation (ADS). The main aims of the design is to provide linear amplifier and filter at the center frequency of 2 GHz and biased at the conditions of class AB. GaAs transistor is used as an active device due to ability in operating at high frequencies and can generate signals with lesser noise. Linearity of the integragted design was simulated with two tone test and the intermodulation products (OIP3) value resulted to be 50 dBm. ACPR of -50.86 dBC with 10MHz frequency spacing is achieved using the Butterworth Bandpass Filter. On the other side, high linearity will lead to more efficient transmission of the signals.

Design of generalized Chebyshev lowpass filter with Defected Stripline Structure (DSS)

This paper presents the design of generalized Chebyshev lowpass filter (LPF) and integrated with Defected Stripline Structure (DSS) using Suspended Stripline Structure (SSS). The study involves circuit analysis to determine generalized Chebyshev responses with a transmission zero at finite frequency in order to produce a reduced number of elements values of prototype circuit. The LPF provides a cut-off frequency at 6 GHz with a return loss better than -19 dB, while the DSS exhibits a notch at frequency of 3.2 GHz with a stopband response better than -40 dB. Thus, the integrated LPF and DSS will produce lowpass and band reject response simultaneously. The design is implemented on a Roger Duroid RO4350 with a thickness of 0.168 mm and dielectric constant, εr of 3.48. The simulation performance results show promising results that could be proved in the experiment works. This new class of integrated LPF and DSS would be useful in any RF/ microwave communication systems particularly in wideband applications where the reduction of overall physical volume, weight and cost is critical to maintaining its good performance.

Design of microstrip bandpass filter with electronically tunable notch response

An integrated high selectivity microstrip wideband bandpass filter with tunable notch response is presented in this paper. The bandpass filter is designed using 7th order short circuited stub filter. Then, the first short circuited stub is replaced with two sections of open circuited stub to exhibit the transmission zeros at lower/higher stopband. The integration with notch filter is realized using U-shape Defected Microstrip Structure (DMS) with varactor diode. By properly varying the DC bias voltages, the notch response can be tuned over a constant bandwidth of around 17%. The experimental result shows that the bandwidth of the wideband bandpass filter is between 2.9 GHz - 5.8 GHz. The notchs tuning range from 4 GHz to 5 GHz is achieved using varactor diode respectively. This type of filter is suitable for applications such as the multi-service and multiband communication system in order to discriminate the undesired signals.

The investigation of reconfigurable SIW filter using varactor diodes

This paper introduces a novel reconfigurable SIW filter for 4G applications by using varactor diodes. This SIW filter consists of two floating islands with two via holes that connected with two varactor diodes. This method allows designing SIW filter with the tunable centre frequency with a constant absolute bandwidth. The filter is designed through the simulation on a standard printed circuit board technology. The SIW filter at 2.097 GHz shows an insertion loss of 1.87 dB and 3 dB bandwidth of 163.39 MHz. SIW filter is used to obtain a good performance that suitable for integration with any reconfigurable planar structure. This investigation provides an alternative solution for reconfigurable SIW filter, particularly in 4G communication systems.