I hereby declare that this project report is based on my original work with the exception of quotations and citations which have been duly acknowledged. I certify that this project report entitled "DUAL-MODE DUAL-BAND MICROSTRIP BANDPASS FILTER" prepared by LIM PAY SUN has met the required standard of submission in partial fulfillment of the requirements for the award of the Bachelor of Engineering (Hons.) Electonic Engineering at Universiti Tunku Abdul Rahman. The copyright of this report belongs to the author under the terms of the Copyright Act 1987 as qualified by the Intellectual Property Policy of the University Tunku Abdul Rahman.
Due credit will always be given to the use of material contained in or derived from this report. I would like to thank everyone who contributed to the successful completion of this project. Lim Eng Hock for his valuable advice, guidance and immense patience during the development of the study.
A compact bandpass filter (BPF) with microstrip interdigital microstrip lines is fabricated and printed on a Duroid 6006 substrate. The measured results of the fabricated filters are in good agreement and in reasonable agreement with the simulated results.
Background
In addition, the losses of the filter play an important role as they affect the performance of the filters.
Aims and Objectives
Project Motivation
Microstrip Filter
Microstrip Lines
- Dielectric Constant
- Effective Dielectric Constant
- Characteristic Impedance
Dielectric constant is a measure of the degree to which it concentrates electrostatic flux lines. In general, the dielectric constant of the substrate will be different (and greater) than air, so the wave travels in an inhomogeneous medium. Since part of the fields from the microstrip conductor exist in air, the effective dielectric constant is less than the substrate's dielectric constant.
Balanis, the effective permittivity can be calculated using the formulas below, where W represents the width of the strip, H represents the height of the substrate, and εr represents the permittivity of the substrate. To minimize the reflection loss at the input port, the characteristic impedance of the microstrip should be equal to the input impedance. Since the height for the substrate is constant, the only variable is the width of the microstrip line.
Fortunately, some of the web applications and software are able to calculate the width of the microstrip lines by entering the desired characteristic impedance, height of the substrate and dielectric constant of the substrate. For example, one of the useful software writers used for characteristic impedance calculation in this project is TX Line 2003.
Microstrip Resonators
- Rectangular Patch Resonators
- Circular Patch Resonators
- Triangular Patch Resonators
A two-mode filter is then designed by appropriately setting two unequal lengths of T-shaped plugs.The resonant behavior of three single-mode patch resonators with sketches shown in Fig. Since the 15.6 mm crossed slots are centrally loaded on the square slot patch, the resonant frequency of the resonator (B) is greatly reduced to 2.45 GHz.
Furthermore, the comparative investigation is applied to demonstrate some attractive features of the inductively loaded patch resonator developed here, such as size reduction and radiation loss. This paper presents the miniaturization of a circular patch by modifying it with a properly oriented cross slit, which increases the path length of the fundamental current but keeps the path length of the second harmonic current unchanged. This reduces the resonance frequency of the fundamental mode and keeps the location of the next higher order mode unchanged, effectively increasing the separation between the two fundamental modes.
In order to reduce the resonant frequency of the fundamental mode, the length of the path taken by the current from one terminal to the other must be increased. In general, the barrier also increases the current path length of the second-order mode, which reduces the harmonic separation between the fundamental and second resonances. Two triangular cuts in the middle were used to introduce coupling between the two rectangular degenerate modes of the TM patch.
The proposed interference technique results in the formation of two attenuation poles on either side of the passband. They also do not occur if interference cuts are made in the first and third quadrants of the patch instead of the second and fourth. The insertion loss of both passband filters was mainly influenced by the substrate loss.
First, the radius of the circular resonator will determine the resonant frequency of the resonator. It should be noted that despite a similarity of the cascaded resonator structure to Figure 2.16(b), while the measured resonator structure in Figure 2.16(c), where the finite transmittance zero compared to the previous filter is on the opposite side of the passband, thereby improving the selectivity on that side as desired.
Background
Research Methodology
Simulation Stage
After consulting supervisor, the simulation result generated by HFSS version 8 is acceptable, HFSS is selected as our simulation software for this project. HFSS was selected as the simulation software to be used in this project, few tutorials were gone through to ensure that author is familiar with the software and practical experience about features first exist in the software before designing using the simulation tool be modeled. It is intended for beginners to understand and use all the features manually, it took the author about a week to complete the tutorials.
Then, a feed line of 50 ohm characteristic resistance is formed to avoid any reflection of the input signal. The characteristic impedance of the supply line can be calculated using equation 2.2 or software such as TX Line 2003. In this project TX Line 2003 was used due to the simplicity and accuracy of the software.
Later, few tests were performed on the microstrip digital bandpass filter. Finally, a final version of the microstrip interdigital bandpass filter configuration is proposed as in Figure 3.1. As shown by studies in Zhu Lei's papers, perturbation elements can be introduced by adding cross slits to a rectangular patch which excites dual degenerate modes.
Running the simulation consumes some time during the filter design process.
Fabrication Stage
Experiment Stage
Proposed Filter Configurations
Results and Discussions
Case Studies
Width
At the same time, the gap distance between the third and fourth striplines also affected the second passband. At the same time, the gap distance between the third and fourth striplines also affected the second passband. At the same time, the width of the second and fourth striplines also affected the second passband.
At the same time, the width of the second and third strips also affected the second passband. At the same time, the width of the first, second and fourth band lines also affected the second pass band. At the same time, the width of the second, fourth and sixth strip lines also affected the second pass band.
By observing Figure 4.18, the second passband clearly disappears as it is affected by W2. At the same time, the distance between g1, g2, g4, g5 and also g6 also affected the second pass band. From Figure 4.23, it can be seen that the second pass band breaks down faster when the width of the third strip line W4=1.10 mm.
By observing Figure 4.24, the second passband clearly disappears as it is affected by W4. By observing Figure 4.25, the second passband clearly disappears as it is affected by W4. From Figure 4.26, it can be seen that the second pass band breaks down faster when the width of the fourth strip line W5=0.92 mm.
By observing Figure 4.27, the second passband obviously disappears as it is affected by W5. By observing Figure 4.28, the second bandpass obviously disappears as it is affected by W5. If we observe Figure 4.30, the second passband obviously disappears as it is affected by W6.
By observing Figure 4.31, the second passband clearly disappears as it is affected by W6. By observing Figures 4.33 and 4.34, the second passband clearly disappears as it is affected by W7.
Conclusion
Recommendation
Therefore, the performance of the filter can be further improved by increasing the number of fingers. They are ideal as tuning, coupling and matching elements where small capacitor values are required and accurate values are needed. Mohamed Azaga1, Masuri Othman, "Design of Microstrip Line Bandpass Filter (BPF) for Ultra Wideband (UWB) Applications" IEEE International Conference on Computer and Communication Engineering., p.
Lei Zhu, Boon Chai Tan and Siang Juay Quek, "Miniaturized Dual-Mode Bandpass Filter Using Inductively Loaded Cross Slotted Patch Resonator" IEEE Microwave and Wireless Components Letters., vol. Yatendra Kumar Singh and Ajay Chakrabartyand, "Miniaturized Dual-Mode Circular Patch Bandpass Filters With Wide Harmonic Separation" IEEE Microwave and Wireless Components Letters., vol. Chiou and C.-Fai.Tai, "Dua-band microstrip band-stop filter using dual-mode loop resonator,” Electron.
Dan Cheng, Hong-Xing Zheng, Li-Ying Feng, and Feng-You Gao, “Investigation of compact second-order microstrip bandpass filter,” IEEE Microw. Erick Emmanuel Djoumessi, and Ke Wu, “Multilayer dual-mode dual-bandpass filter,” IEEE Microwave and Wireless Components Letters., vol.19, no.1, pp.21-23, Jan. Wen-Hua Tu, and Kai Chang, "Piezoelectric transducer-controlled dual-mode switchable bandpass filter," IEEE Microwave and Wireless Components Letters., vol.17, no.3, pp.199-201, Mar.
Wen-Hua Tu and Kai Chang, "Miniaturized dual-mode bandpass filter with harmonic control," IEEE Microwave and Wireless Components Letters., Vol. 17, No. 12, pp. 838-840, Dec. Jung-Woo Baik, Lei Zhu and Yong-Sik Kim, "Dual-mode dual-band bandpass filter using balun structure for single substrate configuration," IEEE Microwave and Wireless Components Letters., vol.20, no.11, pp.613- 615, Nov. Falk Hettstedt, Thomas Lehmann, and Reinhard Knoechel, "Novel dual mode microstrip bandpass filter," IEEE Microwave Magazine., Vol. 16, Feb.
