EFFICIENT MICROSTRIP FILTER DESIGN TECHNIQUE WITH FEBRICATION Vikas Ahirwar, Research Scholar
Jitendra Kumar Ahirwar Asst. Prof., IMEC Sagar
Abstract- The low-pass filter analyzed is one designed according to the criteria established.
As in the rectangular microstrip Ax, Ay, and Az are carefully chosen to fit the dimensions of the circuit. The space steps Ax and Ay are chosen to exactly match the dimensions of the rectangular patch; however, the locations and widths of the ports will be modeled with some error. The proposed architecture is based on a low isolation device and an adaptive cancellation unit. Some low isolation microstrip devices have been considered dual port filter systems are good low design effort choices. Filters or microstrip devices might provide a better solution since they provide some additional level of selectivity against other interfering signals. The proposed new algorithmusesa single cost function based on the superposition of squared errors.
Keywords- Low-pass (LP), High-pass (HP), Band-pass (BP), Band-stop (BS).
1 INTRODUCTION
Filters play an important role in microwave communications and are used to pass or eliminate specific frequency bands.
Filters are classified as low-pass (LP), high-pas (HP), band-pass (BP), and band-stop (BS). LPF is used at the output of a power amplifier to eliminate the harmonics generated by the nonlinearity of the power amplifier, at the output of a mixer to pass only the intermediate frequency, at the input of a receiver to reject the unwanted higher frequencies and in conjunction with a HPF to realize a wideband band-pass filter.
Microwave filters can be divided into two main different types, lumped or distributed. Lumped elements consist of discrete elements, such as inductors and capacitors, while distributed elements use the lengths and widths of transmission lines to create their inductive or capacitive values.
Micro strip line is a good candidate for filter design due to its advantages of low cost, compact size, light weight, planar structure and easy integration with other components on a single board. To achieve better performance for the microwave filters, such as increasing steepness of the cut-off slop, and to increase the stop band range of the microwave filters, defected ground structures (DGS) are used. This technique is realized by etching slots in the ground plane of the microwave circuit.
2 MICROSTRIP
A micro strip line filter type includes stub impedance, step impedance and coupled line filter.
2.1 Design and Optimization of Filter Using Micro Strip Lines
Filter designs beyond 500MHz are difficult to realize with discrete components because the wavelength becomes comparable with the physical filter element dimensions, resulting in various losses severely degrading the circuit performance. Thus to arrive at practical filters, the lumped component filters must be converted into distribution element realizations. Richards Transformation. To accomplish the conversion from lumped and distributed circuit designs, Richards proposed a special transformation that allows open and short circuit transmission line segments to emulate the inductive andthe design of micro strip low pass filters involves two main steps. The first one is to select an appropriate low pass prototype, The choice of the type of response, including pass band ripple and the number of reactive elements, will depend on the required specifications. The element values of the low pass prototype filter, which are usually normalized to make a source impedance g0=1 and a cutoff frequency Ωc=1.0, are then transformed to the L-C elements for the desired cutoff frequency and the desired source impedance, which is normally 50 ohms for micro strip filters.
Most communication system contains an RF front end which
performs signal processing with RF filters. Micro strip filters are a low cost means of doing this. This paper describes the design of low cost and low insertion loss microstrip stepped impedance fractal low pass filter (LPF) by using microstrip layout which works at 0.4GHz for permittivity 4.7 value with a substrate thickness 1.6mm with pass band ripple 0.1dB.Microstrip technology is usedfor simplicity and ease of fabrication.
The filter is required in all RF communication techniques. Low pass filters play an important role in power transmission systems. Transmitted and received signals have to be filtered at a certain frequency with a specific bandwidth. The design of filter is done in the ISM (Industrial, Scientific and Medical) band whose frequency lies between 1.55GHz-3.99GHz. After getting the specifications required, The practical filters have a small non zero attenuation and a small signal output in the attenuation band due to the presence of resistive losses in reactive elements and propagating medium Traditionally, designers used coaxial
lines or waveguides as
transmissionlines, however now new types of filters are designed using micro strip lines.
3 FABRICATION PROCESS IN MICROSTRIP
With the advent of technology, researchers and designers use various technologies aided software’s, machines and techniques for fabricating a micro strip effectively. The modern day technology helps in simulation and designing of a micro strip as per requirement. The fabrication process consists of the following steps:
1. A mask or transparency is prepared with the help of the available software.
2. The next step in the fabrication process consist of creating a photo resist pattern for which a photo resist material (consisting of photo resist solution and plastic tray) and photo resist equipment consisting of Ultra Violet light compartment and temperature controlled hot plate.
3. The next step involved in the process of fabrication consists of
removing or etching the unwanted copper using some common solution so as to get the required copper as conductor pattern.
4. The next step associated with the fabrication process involves preparing a Micro strip housing i.e.
the micro strip base using good conductor materials like aluminum or copper.
5. The final step involves soldering the connectors into the circuit of micro strip after the same are properly screwed with the ground plane.
3.1 Fabrication Technologies
The researchers and designers embarked on the development of printed circuits which were planar in nature and also the efficacy of lumped components in the domain of microwave frequencies subsequent to the development of transmission lines which were planar in nature like the micro strip lines and also the strip lines.The microwave industry witnessed a sea change with the miniaturization as well as the batch fabrication of large number microwave functions in respect of bulk volume production. Preliminary research on printed circuits which were planar in nature
Figure 1 Microstrip
Micro strip transmission lines consist of a conductive strip of width "W" and thickness "T" and a wider ground plane, separated by a dielectric layer (the
"substrate") of thickness "H" as shown in the figure 1. The micro strip has most of its field lines in the dielectric region, concentrated between the strip conductor and the ground plane, and some fraction in the air region above the substrate as shown in fig. Micro strip is by far the most popular microwave transmission line, especially for microwave integrated circuits and MMICs. The major advantage
of micro strip is that all active components can be mounted on top of the board. Having a finite thickness of metal for the conductor strips tends to increase the capacitance of the lines, which affect the effective dielectric constant and the characteristicimpendence.
In the previous years, wireless communication systems has developed tremendously, there was a prompt development in ultra-wideband systems, wireless internet like Wifi and Wimax, broadband personal communication systems and 3G (third generation), 4G (fourth generation) technologies. Due to this rapid development there was a need for more rigid microwave components.
And now day’s satellite systems changed their path from static telecommunications systems to mobile, remote sensing and navigation applications. Microwave components play an important role in the satellite systems. Microwave components include microwave resonant components such as microwave filters, dielectric resonant antenna arrays (DRA), duplexers. Because of the rapid growth in the wireless communication area, it created more challenging requirements that enforce challenges on various novel designs, optimization and understanding of components. In microwave filters the challenges are to be faced in miniaturization, bandwidth, phase linearity, and selectivity of the filters.
4 TYPES OF MICROSTRIP FILTERS AND THEIR APPLICATIONS
4.1 Lowpass and Bandpass Filters Orthodox microstrip low pass and band pass filters such as pseudo-combline filters, stepped-impedance filters, semi- lumped element filters, open-stub filters, end- and parallel-coupled half-wavelength resonator filters, hairpin-line filters, interdigital and combline filters, and stub- line filters, are extensively used in various RF/microwave applications. Different types of lowpass and bandpass filters are listed below:
4.2 Lowpass Filters
There are two main steps in the design of micro strip lowpass filters. The initial one is to select a suitable lowpass model. The type of response, comprising and the number of reactive elements and pass band ripple, will be determined by the required specifications. The low pass
filters are designed approximately in three types, they are:
Stepped-impedance L-C ladder- type lowpass filters
L-C ladder type of lowpass filters using Open-circuited stubs
Semi-lumped lowpass filters having Finite-Frequency Attenuation Poles
4.3 Band Pass Filters
The Bandpass filters are designed approximately in seven types, they are:
End-Coupled, Half-Wavelength Resonator Filters
Parallel-Coupled, Half-Wavelength Resonator Filters
Hairpin-Line Bandpass Filters
Interdigital Bandpass Filters
Combline Filters
Pseudocombline Filters
Stub Bandpass Filters
Filters with 0/4 Short- circuited Stubs
Filters with 0/2 Open-circuited Stubs
4.4 Highpass and Bandstop Filters There are different types of microstrip High pass and Band stop filters are present including, narrow-band and wide- band band stop filters, quasilumped element and optimum distributed high pass filters, as well as filters used for RF chokes. Different types of high pass and bandstop filters are listed below:
4.5 Highpass Filters
The Highpass filters are designed approximately in two ways, they are:
Quasilumped Highpass Filters
Optimum Distributed Highpass Filters 4.6 Bandstop Filters
The Bandstop filters are designed approximately in four ways, they are:
Narrow-Band Bandstop Filters
Band stop Filters with Open- Circuited Stubs
Optimum Bandstop Filters
Bandstop Filters for RF Chokes.
5 METHODOLOGY
The low-pass filter analyzed is one designed according to the criteria established. As in the rectangular microstrip Ax, Ay, and Az are carefully
chosen to fit the dimensions of the circuit.
The space steps Ax and Ay are chosen to exactly match the dimensions of the rectangular patch; however, the locations and widths of the ports will be modeled with some error.
The space steps used are Ax = 0.4064 mm, Ay = 0.4233 mm, and Az = 0.265 mm, and the total mesh dimensions are SOX lOOX 16 in the 2, 9, and 2 directions respectively.
The long rectangular patch is thus 50Ax X6 Ay. The distance from the source plane to the edge of the long patch is 50 A y, and the reference planes for ports 1 and 2are 10 Ay from the edges of the patch. The strip widths ofports 1 and 2 are modeled as 6Ax.
The time step used is At = 0.441 ps. The Gaussianhalf-width is T = 15 ps and the time delay t,, is set to be3T. The simulation is performed for 4000 time steps toallow the response on both ports to become nearly 0.
Fig. 2 Computational Domain 5.1 Design & Simulation
Fig. 3 Proposed Design Simulation Analysis
Total mesh dimensions and grid cells sizes
nx = 80; ny = 40; nz = 100;
dx = 0.4064e-3; dy = 0.4233e-3; dz = 0.2650e-3;
Fig. 4 Proposed Design Simulation Analysis
Total mesh dimensions and grid cells sizes (without PML)
nx = 80; ny = 30; nz = 70;
dx = 0.4064e-3; dy = 0.4233e-3; dz = 0.2650e-3;
Fig. 5 Proposed Design Simulation Analysis
5.2 Ground Plane
Index((1+PML):(nx-PML), (1+PML):(ny-PML), PML+1) = 2;
Rectangular patch (one cell thickness)
Index((nx/2-20):(nx/2+20), (ny/2- 3):(ny/2+3), PML+5) = 2;
Transmission line from port 1 to rectangular patch
Index((nx/2-10):(nx/2-5), (PML+1):ny/2, PML+5) = 2;
Transmission line from rectangular patch to port 2
Index((nx/2+5):(nx/2+10), ny/2:(ny- PML), PML+5) = 2;
Dielectric substrate between ground plane and filter patch
Index((1+PML):(nx-PML),
(1+PML):(ny-PML), (PML+2):(PML+4))
= 3;
Matched load before port 1
Index((nx/2-10):(nx/2-5), PML+1, (PML+2):(PML+4)) = 4;
Matched load after port 2
Index((nx/2+5):(nx/2+10), ny-PML, (PML+2):(PML+4)) = 4;
The spatial distribution of E,(x, y, t ) just beneath the microstrip at 200, 400, 600, and 800 time steps The scattering coefficient results, 9 and 10, again show good agreement in the location of the response nulls. The desired low-pass filter performance is seen in the sharp S,, roll- off beginning at approximately 5 GHz.
There is again some shift near the high end of the frequency range. In the S,, results, the stopband for the calculated curve is somewhat narrower than the measured results. Some experimentation with planar circuit techniques has led to the conclusion that this narrowing is caused predominantly by the slight
misplacement of the ports inherent in the choice of Ax and Ay.
6 RESULT DISCUSSION
Table 1 Result Discussion Parameter
Type
TOTAL MESH DIMENSIONS
GROUND PLANE Size nx = 80; ny =
40; nz = 100; Index((nx/2- 10):(nx/2-5), (PML+1):ny/2, PML+5) = 2;
Frequency 4.5 G-6GHz &
14GHz -20GHz
6.2 G-12 GHz / 17-20 GHz Performance
based on Design
High below 10 db After 14 GHz
Moderate below 10 db after 6.2 GHz and high @ 17 GHz
Geometry based design approach
Most preferred design Approach
Alternate Design Approach
7 CONCLUSION
Novel architecture is proposed and described in this eliminates many external components in the multi-band filters. This solution handles the desensitization problem and receiver sensitivity problem due to Tx leakage in multi-band port front end.
The proposed architecture is based on a low isolation device and an adaptive cancellation unit. Some low isolation microstrip devices have been considered dual port filter systems are good low design effort choices.
REFERENCES
1. Hui Zhao and Juebang Yu, “A Novel Neural Network-based Approach for Designing Digital Filters” IEEE International Symposium on Circuits And Systems, June9- 12, 2020, Hong-Kong”
2. Wu-Sheng Lu, Minimax “Design Of FIR Filters With Low Group Delay Using Enhanced Sequential Quadratic Programming” Dept. of Elec. and Comp Engineering University of Victoria Victoria, BC, Canada V8W 3P6 2020 3. Arojit Roychowdhury “FIR Filter Design
Techniques” M. Tech. credit Seminar report Electronic Systems Group, EE Dept, IIT Bombay, submitted November 2019
4. Xiaohua Wang and Xianzhi Meng, “ A Novel Neural Networks-Based Approach for Designing FIR Filters” Proceedings of the 6th World Congress on Intelligent control and Automation, June 21-23, 2016 Dalian , China 5. Amanpreet Kaur, “Design of FIR Filter Using Particle Swarm Optimization Algorithm for Audio Processing “ International Journal of Computer Science and Network
(IJCSN) Volume 1, Issue 4, August 2012 6. Lo-Chyuan Su,“ Neural Least-Squares Design
of FIR Digital Filters with Trigonometric Properties. “WHAMPOA An
Interdisciplinary Journal 54 (2008) (103- 110).
7. S. M. Shamsul Alam, “Performance Analysis of FIR Filter Design by Using Optimal, Blackman Window and Frequency Sampling Method “International Journal Electrical &
Computer Sciences” IJECS-IJENS Vol:10, No:
01 (13-18).
8. Ricardo A. Losada. “Practical FIR Filter Design in MATLAB “The Math Works Inc.
Apple Hill Dr. Natick, MA 01760, USA March 31, 2003 ”
9. [9]Sheenu Thapar, “A Low Pass FIR Filter Design Using Genetic Algorithm Based Artificial Neural Network “International Journal of Computer Technology and Electronics Engineering (IJCTEE) Volume 2, Issue 4, August 2012
10. Yong Ching Lim, “A Weighted Least Square Algorithm for Quasi Equiripple FIR and IIR Digital Filter Design “Tranasactions On Signal Processin Vol.40. NO. 3. March 1992, (551- 558)
11. Graham. Goodvin and Kwai Sang Sin, Applied To Problfms In Prediction Filtering And Control Study of A Particular Adapative Paraketw Estimator “Department of Electrical and Computer Engineering The University of Newcastle New South Wales, 2308,” Australia.
12. V. Ralph Algazi “On the Frequency Weighted Least Square Design of Finite Duration Filters”, IEEE Ansactions on circuits and systems, VOL. CAS-22,
13. Nasir Mahmood Asif, “A Unified approach Using Neural Networks efficient Algorithms in Audio Signal Processing” Engineering College National University of Science and Technology.
14. David Hermann, “window based prototype filter design for highly oversampled filter bankin audio application” IEEE (ICASSP) April 16- 20, 2007 Honolulu.
