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Multiple-mode stub-loaded resonator with quad channel diplexer and tri-band bandpass filter are presented and analyzed theoretically in this paper. The multi-mode stub-loaded resonator employs the basic structure of a triple mode resonator. Herein, the triple-mode resonator is modified by introducing a mid-coupled line between the odd mode resonances to produce a quad-mode resonator. The proposed resonator is applied in the quad-channel diplexer design, composing of two independent dual-band bandpass filters. In turn, the triple-band bandpass filter based on a parallel quad-mode and a dual-mode stub-loaded resonator is developed. To validate the performance of the proposed resonators, two experimental examples, including a quad-channel diplexer and a triple-band bandpass filter are fabricated and measured. Each of the designed circuits occupies small area i.e. about 0.32lambda*0.22lambda and 0.18lambda*0.20lambda respectively. Good agreements between simulated and measured results are achieved.

The high peak-to-average power ratio (PAPR) is one of the major problems of orthogonal frequency division multiplexing (OFDM) systems in wireless transmission.Therefore, partial transmit sequence (PTS), a promising scheme that can provide good PAPR reduction performance, has been proposed for OFDM transmission to eliminate distortion. The PTS method divides the input data block into disjoint sub-blocks, computes Inverse Fourier Transform of the subblocks, rotates the sub-blocks with appropriate phase factors and combines them to form the transmitted signal.This paper presents an enhanced PTS approach that combines two PTS partitioning schemes (adjacent and interleaved) to effectively reduce the PAPR of the OFDM systems. The influence of the proposed approach on performance is investigated by varying the size of the disjoint sub-blocks.The PAPR reduction performance of the proposed PTS method is compared with two well known sub-blocks partitioning schemes, namely, Adjacent Partitioning (AP), Interleaved Partitioning (IP).The various computer simulation results for the various sub-blocks confirmed that the proposed method provides better PAPR reduction performance compared with AP and IP partitioning based PTS scheme. In addition, these PTS schemes largely depend on the chosen size of the partitions.

This paper presents a new design of miniaturized wideband bandpass filter using microstrip hairpin in multilayer configuration for X-band application. The strong coupling required for wideband filter is realized by arranging five hairpin resonators in two layers on different dielectric substrates. Since adjacent resonator lines are placed at different levels, there are two possible ways to change coupling strength by varying the overlapping gap between two resonators; vertically and horizontally. In this paper, simulated and measured result for a wideband filter of 4.4 GHz bandwidth at 10.2 GHz center frequency with fifth order Chebyshev response is proposed. The filter is fabricated on 0.254 mm thickness R/T Duroid 6010 and R/T Duroid 5880 with dielectric constant 10.2 and 2.2 respectively using standard photolithography technique. Two filter configurations based on vertical (Type 1) and horizontal (Type 2) coupling variation to optimize the coupling strength are presented and compared. Both configurations produce very small and compact filter size, at 5.0 x 14.6 mm2 and 3.2 x 16.1 mm2 for the first and second proposed filter type respectively. The measured passband insertion losses for both filters are less than 2.3 dB and the passband return loss is better than -16 dB for filter Type 1 and -13 dB for filter Type 2. Very small and compact filter is achieved where measured results show good agreement with the simulated responses.

This paper presents an Ultra-Wide Band (UWB) microstrip filter which is initially modeled from a quarter-wavelength short-circuited stubs, without the use of any vias. All vias that provide short circuit stubs are replaced by microstrip patches which have low impedance at high frequency. The purposes of substituting the vias are to simplify the fabrication process and reduce losses due to capacitive effects of vias. The microstrip patch impedance is determined by calculation and simulation in such a way that optimum S-parameters and frequency responses are obtained. The measured S-parameters have shown encouraging results of –3 dB cut-off frequencies from 3.58 GHz to 10.57 GHz with minimum magnitude of insertion loss better than 1 dB and return loss of better than –16.9 dB in the passband. The final dimension of “via-less” UWB microstrip filter is measured at 41.0 × 15.1 mm2.

In radio frequency and microwave systems, filters are the most essential component to select the required signals. They are built together with other components such as mixers, amplifiers, oscillators and switches. Filters work by blocking the unwanted signals and allowing the desired signals through them before feeding it into other components or devices. In the latest interest and future radio frequency and microwave high speed communication technology like Ultra-Wideband (UWB), a bandpass filter with large bandwidth (> 500 MHz) is required to fulfill the specifications. This is due to the UWB format signal which uses very short time pulse wave within 1.0 ns to 0.1 ns. This thesis presents theories, methods, parameters, simulations and measurements of designed and development of bandpass filters to support UWB communication systems. There are four types of bandpass filters which are designed and developed to operate within 3.1 GHz to 10.6 GHz to support the UWB frequency range specification.Initially, the designed model is derived from J-inverter which it is a transformation of low pass to bandpass Chebyshev filter. Type of response is chebyshev since it is able to perform an equal-ripple return loss response in the whole passband. The equal-ripple return loss response can keep the insertion loss almost flat in the whole pass band and sharp-out-of-band rejection response. In the thesis, bandpass filters are designed and developed based on five poles quarterwavelength short-circuited stubs model. The model is theoretically capable to expand the frequency bandwidth by tuning its h (interior admittance level of the stubs) factor. The related mathematical equations are applied into mathematical software to speed up the optimization of h factor and obtain the required admittance level for stubs and transmission lines. The first bandpass filter has successfully shown the expansion in frequency bandwidth to support Ultra-wideband specifications. The filter uses five vias

This paper presents a novel compact “via-less” UWB filter derived from a quarter-wavelength short-circuited stubs model. In this compact “via-less” UWB filter, there is no connecting vias as short circuit elements. Unlike its previous model that has 5 short-circuited stubs, this novel shape consists of two pairs of stubs which are joint together to share on the same microstrip patch and thus reduces total size of the UWB filter itself making it more compact in nature. With proper width optimization, the microstrip patch is able to decouple and provides low impedance to the ground in the UWB frequencies range. The filter delivers 3.85GHz to 10.44 GHz frequency range with 92.23% of fractional bandwidth. The magnitude of insertion loss is below than 0.53 dB and the return loss is lower than −14.8dB in the passband frequencies. The −3 dB bandwidth is from 3.85 GHz to 10.44 GHz with 92.23% of fractional bandwidth. The group delay only varied by 0.47 ns in the passband, which makes it suitable for radio communication systems.

Five poles quarter-wave short-circuited stubs is designed and developed to support the ultra-wide band (UWB) applications. The filter, with a total size of 41 mm × 12 mm operates within 2.7–9.83 GHz, produces a fractional bandwidth of greater than 100%. The filter is fabricated on RT/Duroid 5880 board with thickness of 0.508 mm. Measured results indicate that the filter, consisting of five short-circuited stubs, and a stepped impedance transmission line can cover up to 114% bandwidth within UWB frequency range with insertion loss (S21) better than 1.27 dB.

We present here a new pattern with compact size of Ultra Wideband (UWB) microwave filter. The filter is based on quarter-wave length short-circuited stubs model. We introduced here a new schematic model by extracting all parasitic elements such as T-junction and discontinuity in our new pattern of UWB filter. This new filter has minimal number of vias and improved frequency bandwidth, insertion loss and return loss. It is fabricated on RT Duroid 5880 with 0.508mm of substrate thickness. The final dimension is measured as 21mm×14 mm. It is not only compact, but also delivers excellent scattering parameters with magnitude of insertion loss, |S21| lower than 0.85 dB and return loss better than -11.6 dB. The fractional bandwidth is 109% from 3.06 GHz to 10.43 GHz. In the pass band, the measured group delay varies in between 0.47 ns to 0.32 ns, showing stability with minimum variation of only 0.15 ns.

A narrowband trisection substrate-integrated waveguide elliptic filter with coplanar waveguide (CPW) input and output ports is proposed and demonstrated for X-band applications. The filter is formed by incorporating metallized vias in a substrate (RT/Duroid) to create cross-coupled waveguide resonators. The result is an attenuation pole of finite frequency on the high side of the passband, therefore exhibiting asymmetric frequency response. The fabricated trisection filter with a centre frequency of 10.05 GHz exhibits an insertion loss of 3.16 dB for 3% bandwidth and a return loss of -20 dB. The rejection is larger than 15 dB at 10.37 GHz.

In this paper, a compact 5 poles Ultra-Wideband (UWB) microwave filter is designed by using a quarter wave short-circuited stubs. The UWB filter bandwidth is covered from 2.75 GHz to 10.0 GHz. This filter designed is developed from a Low Pass Chebychev prototype with a 0.1 dB passband ripple. The first pattern layout uses 5 vias connecting to the ground. This pattern layout is then re-arranged to reduce the total area space needed on microstrip by maintaining the optimum filter response. Finally, a compact microwave filter with 21 mm X 16.1 mm dimension is presented here with excellent scattering characteristic results.

This paper is a study on the design of microwave waveguide filter suitable for micromachining process. Novel structure and processes are introduced which allow accurate fabrication of low loss waveguide filter. This new technique applies micro-fabrication processes to improve fabrication accuracy. A W-band micromachined rectangular waveguide filter utilizing SU-8 micromachining with CPW input and output ports has been designed. Simulated frequency responses exhibit insertion loss of 1.18 dB across 1 GHz bandwidth for W-band frequency range centered at 93 GHz with return loss better than -20 dB.

In this paper, a compact 5 poles ultra-wideband (UWB) microwave filter is designed by using a quarter wave short-circuited stubs. The UWB filter bandwidth is covered from 2.75 GHz to 10.0 GHz. This filter designed is developed from a low pass Chebychev prototype with a 0.1 dB passband ripple. The first pattern layout uses 5 vias connecting to the ground. This pattern layout is then re-arranged to reduce the total area space needed on microstrip by maintaining the optimum filter response. Finally, a compact microwave filter with 21 mm times 16.1 mm dimension is presented here with excellent scattering characteristic results.

Radio Frequency Identification (RFID) system has been widely used recently to replace a bar code system. The purpose of the RFID device is the same as a bar code device that provides a unique identifier data for an object. In the bar code device, the identifier data is printed on the object, while in the RFID device the identifier data can be stored and updated from time to time because it has a small size of memory chip or microprocessor located in its tag. Besides that, the RFID device does not need a line of sight to retrieve the data from the tag since it uses a magnetic wave or radio frequency wave at 134.2 KHz or 13.56 MHz to communicate between the reader and tag. The common RFID reader in the market nowadays is using a wire communication between the reader and the host computer. This limits the reader performance since it is not portable. To make it portable, the device can be connected to the Personal Digital Assistant (PDA) or Bluetooth wireless device, but the solutions are costly. In this thesis, the research is concentrated on the design and development of the communication system between the reader and the host computer. The communication between the RFID reader and the computer host is by using wireless and the communication is set to RS232 protocol. The system is operated at UHF 370 MHz band and it uses an amplitude shift keyed (ASK) modulation technique The system is established by modulating the amplitude of the high bit or bit ‘1’ of the signal at radio frequency wave at the UHF carrier wave. For the low bit or bit ‘0’ there is no radio frequency (RF) modulation taken place at the transmitter circuit, therefore the receiver does not receive any RF modulation wave from the RF transmitter reader and this is defined as low bit or bit ‘0’ at the receiver. This RFID wireless reader communication system can provide a good communication range in between 20 to 30 meters for line of sight or without line of sight. It is very useful for the outdoor such as

In this paper, the proposed communication between the RFID reader and computer host is by using wireless and the communication is set to RS232 protocol. The system is operated at UHF band (378 MHz) and it uses an amplitude shift keyed modulation technique. The system is established by modulating the amplitude of the high bit or bit ‘1’ of the signal at radio frequency wave at the UHF carrier wave. For the low bit or bit ‘0’ there is no RF modulation taken place at the transmitter circuit, therefore the receiver receives a low input and defines it as the bit ‘0’. This RFID wireless reader communication system can guarantee a good communication range in between 20 to 30 meters line of sight or without line of sight. It is very useful for the outdoor such as tree tagging and electronic gardening applications.

This paper discusses the design and development of cafeteria system equipped with RFID system to enhance the flow of item identification and payment process. The goal of the study is to reduce the total time spend in the process by automating the manual task involved by using RFID. In this project, the proposed solution is to tag the food container with RFID transponder so that it could carry information associated with the container. The information contained in the transponder is the most vital component of the automation process. RFID transponder enables the information to be carried from the ordering counter to the payment counter. As RFID transponder communicates by using radio signal, they do not require line of sight between the transponder and the reader antenna. The reader system at the payment counter is able to read multiple RFID tag in the reader’s field. Therefore, total price and number of items purchased, is automatically determined by the software in the computer at the counter. Manual verification is only needed to make sure that the automation process works as intended. An RFID-based payment system is also used to further reduce the total time spent in the process.