Asia-Pacific Journal of Advanced Research in Electrical and Electronics Engineering Vol. 1, No. 1 (2017), pp. 39-46 http://dx.doi.org/10.21742/ajaeee.2017.1.1.04
Performance Comparison of Microstrip Band-Pass Filters for Different Dielectric Materials Vivek Singh Kushwah1, G.S. Tomar2, Sarita Singh Bhadauria3 1
Dept. of Electronics, Amity School of Engineering & Technology, Gwalior, India 2 THDC IHET, Tehri and MIR Labs Gwalior, Gwalior, India 3 Dept. of Electronics, Madhav Institute of Technology & Science, Gwalior, India
[email protected],
[email protected],
[email protected] Abstract
In this paper performance has been compared for various designs of Microstrip bandpass filters with different dielectric materials for GSM Guardband applications. The results are investigated using standard performance parameters in the range of frequency. IE3D 14.1 simulation tool has been used for obtaining the Insertion loss and return loss values of microstrip filters of the subject designs. The fabricated design has been subjected to the comparison and results are in accordance to the expected lines. Keywords- Microstrip Filters, Return Loss, IE3D EM Simulation, Scattering parameters, Insertion Loss
1. Introduction The present communication systems are going wireless at fast pace and need to have better quality of components, which are being used in wireless communication systems. Filters are one of the primary components used for selection of wanted signals to have communication with better performance. Microwave filters are commonly used for passing the desired band of frequencies and rejecting other frequencies for various modern microwave applications such as satellite-communication, Radar and mobile communication etc [1]. The work is focused on filter design, mathematical modeling of the filter designs along with the determining performance parameters like scattering parameters and losses. Almost every wireless communication systems have been brought in the microwave frequency range. In this range of frequency various active and passive components need to be fabricated with greater care and efficiency to obtain expected performance for better and efficient communication. The filters need much care and consideration as it is vital component in the communication systems to select the actual band of frequencies needed or need to be rejected, depending on the position of the filter in the communication system. Filters are an integral component of any microwave communication system. Filters are essential to perform task of separating, sorting of signals and impedance matching in communication systems [2]. Filters are also applicable in Radio Frequency front-ends as pre-select filters where pre-select filters select the desired frequency band. It is also highly recommended to have good quality of band reject filters with high insertion loss at its center frequency to reject selected pass band, which may be communicated in common media along with required base band [3]. There is also need for having high quality low/high pass filters at this range of frequency as to give better options of selection for various required or not required band of frequencies. Most of the communication systems require an RF front end LNA and filters processing elements for analog signal at the input [4]. This stage is an important stage in any communication system and needs high quality of filtering devices. The microstrip filters are generally used in transmitters and receivers at frequency ranges beyond 800 MHz.
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Asia-Pacific Journal of Advanced Research in Electrical and Electronics Engineering Vol. 1, No. 1 (2017)
There have been many designs, which are proposed by researchers for various types of filters [5-12]. The basic design structure of the filters has been investigated by revisiting primary characteristics of the material and their applications according to the required applications and requirements. The design is considered with standard patch and modifications thereon for achieving parameters as desired. Various types of dielectric materials are proposed for the design of microstrip filters in GSM band of frequencies on microstrip patch which have reduced filter size drastically and have given better option for various design considerations and options to have sharp cutoff, improved bandwidth and high performance filter design. In this work performance comparison of Microstrip band pass filter is presented for various dielectric materials.
2. Fundamental Design of Microstrip Band- Pass Filters Microstrip Band-pass filters may also be designed with a large number of stubs as illustrated in Figure 1. In this type of filter all the branches i.e. connecting lines and all stubs have different dimensions and it is quarter guided wavelength (λg0/4) long where λg0 is the guided wavelength for the design. The filter characteristics based on the characteristic admittances of the stub lines represented as Yi and the characteristic admittances of the linking lines represented as Yi,i+1. A microstrip line has become popular planar component for design of microstrip filter which has a single ground plane and thin strip conductor on a low loss dielectric substrate above the ground plane and input-output are drawn using one of the popular coupling techniques by mounting on the surface of the component. The various shapes and dimensions are key component of filter type and operational range. The performance of filters is measured on the basis of Scattering Parameters.
Figure. 1 Basic design of microstrip filter with the stubs
Dimensions of filter are calculated with the help of Characteristic admittance and Characteristic admittances can be derived by using design equations (1-8). 𝜽=
h=2
𝝅 𝑭𝑩𝑾 �𝟏 − � 𝟐 𝟐
𝑱𝟏,𝟐 𝒉𝒈𝟏 = 𝒈𝟎 � , 𝒀𝟎 𝒈𝟐
𝒉𝒈𝟎 𝒈𝟏 𝑱𝒊,𝒊+𝟏 = � 𝒀𝟎 𝒈𝒊 𝒈𝒊+𝟏
40
𝑱𝒏−𝟏,𝒏 𝒉𝒈𝟏 𝒈𝒏+𝟏 = 𝒈𝟎 � 𝒀𝟎 𝒈𝟎 𝒈𝒏−𝟏 𝒇𝒐𝒓 𝒊 = 𝟐 𝒕𝒐 𝒏 − 𝟐
(𝟏) (𝟐) (𝟑)
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Asia-Pacific Journal of Advanced Research in Electrical and Electronics Engineering Vol. 1, No. 1 (2017)
𝑱𝒊,𝒊+𝟏 𝟐 𝒉𝒈𝟎 𝒈𝟏 𝒕𝒂𝒏𝜽 𝟐 � +� � 𝒀𝟎 𝟐 𝒇𝒐𝒓 𝒊 = 𝟏 𝒕𝒐 𝒏 − 𝟏 𝒉 𝑱𝟏,𝟐 𝒀𝟏 = 𝒈𝟎 𝒀𝟎 �𝟏 − � 𝒈𝟏 𝒕𝒂𝒏𝜽 + 𝒀𝟎 �𝑵𝟏,𝟐 − � 𝒀𝟎 𝟐 𝑵𝒊,𝒊+𝟏 = ��
(𝟒) (𝟓)
𝑱𝒏−𝟏,𝒏 𝒉 𝒀𝒏 = 𝒀𝟎 �𝒈𝒏 𝒈𝒏+𝟏 − 𝒈𝟎 𝒈𝟏 � 𝒕𝒂𝒏𝜽 + 𝒀𝟎 �𝑵𝒏−𝟏,𝒏 − � 𝒀𝟎 𝟐
𝒀𝒊 = 𝒀𝟎 �𝑵𝒊−𝟏,𝒊 + 𝑵𝒊,𝒊+𝟏 −
𝒇𝒐𝒓 𝒊 = 𝟐 𝒕𝒐 𝒏 − 𝟏
𝑱𝒊−𝟏,𝒊 𝑱𝒊,𝒊+𝟏 − � 𝒀𝟎 𝒀𝟎
(𝟔)
(𝟕)
𝑱𝒊,𝒊+𝟏 (𝟖) � 𝒇𝒐𝒓 𝒊 = 𝟏 𝒕𝒐 𝒏 − 𝟏 𝒀𝒊,𝒊+𝟏 = 𝒀𝟎 � 𝒀𝟎 Here Y0 is the Characteristic admittances of the line. Characteristic admittances of inverters are denoted as Ji,i+1 ,h is the constant which is unitless, the element values of prototype filter are g0, g1 and gn such as a Chebyshev, given for a normalized cutoff Ωc = 1.0.FBW is the fractional bandwidth of the filter which is used to decide the bandwidth of filter. For five short circuited stubs, The prototype parameters of bandpass filter are in standard and fixed format. g0 =1, g1 = 1.1468 , g2 =1.3712, g3 = 1.9750, g4= 1.3712, g5 = 1.1468 , g6 = 1.0 The various design parameters of microstrip filter is calculated for 1.8 GHz frequency using standard design equations. The characteristic admittance of all the stubs and connecting microstrip line is listed in Table 1. Table 1. Characteristic admittance of microstrip line
i 1 2 3 4 5
admittance of stubs in mhos 𝑌𝑖 0.03514 0.06931 0.06823 0.06935 0.03524
admittance of connecting line in mhos mhos (𝑌𝑖,𝑖+1 ) 0.02586 0.02786 0.02786 0.02586
3. Performance Comparison Of Microstrip Band- Pass Filters Three Dielectric materials are mostly used as a substrate for fabrication of Microstrip filters. (1) RT/Duroid 6010 LM which has Dielectric Constant (εr) of 10.2 , Thickness(h)=0.635 mm, Loss tangent (δ) =0.0023 (2) Dielectric Material FR4 Substrate which has the following properties : Dielectric Constant (εr) =4.4 , Thickness(h)=1.6 mm, Loss tangent (δ) =0.02 (3) RT/Duroid 6006: Dielectric Constant (εr) = 6.15 , Thickness(h)=1.27 mm, Loss tangent (δ) =0.0027 (1) For Dielectric Material RT/Duroid 6010 LM: It has Dielectric Constant (εr) = 10.2, Thickness (h)=0.635 mm, Loss tangent (δ) =0.0023
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Asia-Pacific Journal of Advanced Research in Electrical and Electronics Engineering Vol. 1, No. 1 (2017)
The widths and guided wavelengths linked with the characteristic admittances of microstrip line can be derived with the help of designed equations and are summarized in Table 2. Table 2. Basic Design Parameters of first Microstrip Filter
Stubs Width of Microstrip stubs in mm 1 1.6 2 4 3 3.9 4 4 5 1.6
Quarter Guided Wavelength in mm 15 14.47 14.48 14.47 15
Width of Length of Connecting Connecting lines lines 0.97 1.10 1.10 0.97
15.6 15.5 15.5 15.6
The basic design of microstrip filter is shown in Figure 2 which is obtained by using some mathematical calculations with the help of design equations for microstrip filter and plotted by using IE3D electromagnetic simulation software. It consists of five stubs of quarter guided wavelength long linked with each other with the help of connecting microstrip lines. The 50 ohm terminating microstrip line is used for connecting the 50 ohm load/port so that input is provided to the microstrip filter through input port and output characteristics response is measured from the output port. The total area of the proposed design of microstrip filter is 1152 mm2 which is more compact as compared to existing designs [2-8]. Length of the proposed filter is 72mm and width of the proposed filter is 16mm.Fabricated design of proposed microstrip filter is shown in Figure 3.
Figure 2. Fundamental Design of first Microstrip Filter for RT/Duroid 6010 LM
Figure 3. Fabricated Design of Microstrip Filter with stubs
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Asia-Pacific Journal of Advanced Research in Electrical and Electronics Engineering Vol. 1, No. 1 (2017)
(2) For Dielectric Material FR4 Substrate: This material has the following properties: Dielectric Constant (εr =4.4), Thickness h=1.6 mm, Loss tangent (δ) = 0.02 Table 3. Basic Design Parameters of second Microstrip Filter
Stubs Width of Quarter Guided Microstrip stubs Wavelength in in mm mm 1 6.94 21.97 2 16.17 21.04 3 15.86 21.06 4 16.17 21.04 5 6.94 21.97
Width of Length Connecting Connecting lines lines 4.498 22.457 5.01367 22.3378 5.01367 22.3378 4.498 22.457
of
Figure 4. Fundamental Design of second Microstrip Filter with stubs
(3)For RT/Duroid 6006: Dielectric Constant (εr) = 6.15, Thickness (h)=1.27 mm, Loss tangent (δ) =0.0027
Figure 5. Fundamental Design of third Microstrip Filter with stubs
Table 4. Basic Design Parameters of third Microstrip Filter
Stubs Width of Quarter Guided Width of Length of Microstrip Wavelength in Connecting Connecting stubs in mm lines lines mm 1
4.48
19
2.84
19.5
2
10.6
18
3.18
19.37
3
10.4
18.1
3.18
19.37
4
10.6
18
2.84
19.5
5
4.48
19
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Asia-Pacific Journal of Advanced Research in Electrical and Electronics Engineering Vol. 1, No. 1 (2017)
4. Implementation and Results Figure 6 illustrates the frequency response of microstrip band pass filter for the dielectric material RT/Duroid 6010 LM which shows the bandwidth of the filter ranges from 1.24 to 2.26 GHz for GSM guard-band applications.
Figure 6. IE3D EM simulated performance of the first microstrip bandpass filter for RT/Duroid 6010 LM dielectric substrate
Performance of the filter is measured in terms of return- loss and insertion-loss which is measured in the form of S- parameters (S11, S21). Figure 7 shows the frequency response of microstrip band pass filter for the dielectric material FR4 Substrate which shows the bandwidth of the filter ranges from 1.2 to 1.8 GHz for mobile communication. It has very low return loss and high insertion loss as compared to previous design.
Figure 7. IE3D EM simulated performance of the second microstrip bandpass filter for Glass Epoxy FR4 dielectric substrate
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Asia-Pacific Journal of Advanced Research in Electrical and Electronics Engineering Vol. 1, No. 1 (2017)
Figure 8 illustrates the frequency versus return/ insertion loss response of microstrip band pass filter for the dielectric material RT/Duroid 6006 Substrate which shows the bandwidth of the filter ranges from 1.5 to 1.8 GHz for narrowband application. It also has very low return loss and high insertion loss as compared to previous design.
Figure 8. IE3D EM simulated performance of the second microstrip bandpass filter for RT/Duroid 6006dielectric substrate
Table 3 represents the performance comparison of microstrip filter in terms of return and insertion loss for various dielectric substrates. Table 5. Performance Comparison of Microstrip Filter for different substrate
Material/Substrate RT/Duroid 6010 LM
Return loss in dB -37.1 dB
Insertion Loss in dB -0.52 dB
Bandwidth
Glass EpoxyFR4
-11.9 dB
-2 dB
1.24 to 2.26 GHz 1.2 to 1.8 GHz
RT/Duroid 6006
-5.3 dB
-2.2 dB
1.5 to 1.8 GHz
It is obvious from table 5 that most suitable substrate for the designing of microstrip band-pass filter is RT/Duroid 6010 LM which provides wide bandwidth and improved insertion and return loss with compact structure as compared to other substrates.
5. Conclusion In this paper three types of dielectric substrates are used for the performance and design comparison of Microstrip band-pass filters which is used for GSM guard-band applications. Scattering parameters are calculated from the simulated performance of the filter in terms of insertion and return loss. It is concluded that RT/Duroid 6010 LM is the best dielectric substrate for obtaining good bandwidth, better performance and compact size as compared to other two substrates.
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Asia-Pacific Journal of Advanced Research in Electrical and Electronics Engineering Vol. 1, No. 1 (2017)
References [1] J.S.G. Hong and M.J. Lancaster, “Microstrip Filters for RF/Microwave Applications”, (1/e),John Wiley & Sons Inc., (2001). [2] D.M. Pozar, “Microwave Engineering” (2/e), John Wiley, (2000). [3] Y.S. Mezaal and H.T. Eyyuboğlu, “A New Narrow Band Dual-Mode Microstrip Slotted Patch Bandpass Filter Design Based on Fractal Geometry,” 7th IEEE International Conference on Computing and Convergence Technology (ICCCT), pp. 1180-1184, (2012). [4] A.M. Abbosh, “Design Method for Ultra-Wideband Bandpass Filter With Wide Stopband using Parallel-Coupled Microstrip Lines,” IEEE Transactions on Microwave Theory and Techniques, Vol. 60, No. 1, pp. 31-38, (2012). [5] L.W. Cross, M.J. Almalkawi and V.K. Devabhaktuni, “Theory and Demonstration of Narrowband Bent Hairpin Filters Integrated With AC-Coupled Plasma Limiter Elements,” IEEE Transactions on Electromagnetic Compatibility, No. 99, pp. 1-7, (2013). [6] P. Chakravorty, “A Microstrip Wideband Bandpass Filter based on λ/2 Stub with Spurious Passband Suppression Scheme,” Taylor & Francis; International Journal of Electronics, Vol. 100, pp. 37-41, (2013). [7] L. Tan, Qiang Li, Ruijie Li and J. Teng, “Design of Transimpedance Low-pass Filters,” Taylor & Francis; International Journal of Electronics, Vol. 100, pp. 142-149, (2013). [8] J. Xu, Y.X. Ji, C.H. Chen and W. Wu, “Compact and High Performance Bandpass Filter and Diplexer Based on SCMRC-loaded SIR,” Taylors and Francis; International Journal of Electronics, Vol. 100, pp. 1-13, (2013). [9] S. Fallahzadeh, A. Akbarzadeh and M. Tayarani, “Spurious Response Suppression in Microstrip Bandpass Filters using Defected Microstrip Structures,” Taylors and Francis; International Journal of Electronics, Vol. 100, pp. 389-400, (2013). [10] Y.H. Cho and S.W. Yun, “Design of Balanced Dual-Band Bandpass Filters using Asymmetrical Coupled Lines,” IEEE Transactions on Microwave Theory & Techniques, Vol. 61, No. 8, pp. 2814-2820, (2013). [11] G.S. Tomar, V.S. Kushwah and S.S. Bhadauria, “Artificial Neural Network Design of Stub Microstrip Band-pass Filters,” International Journal of Ultra-wideband Communication Systems, Inderscience publishers, Vol. 3, No. 1, pp. 38-49, (2014). [12] V.S. Kushwah, G.S. Tomar and S.S. Bhadauria, “Design of Grooved Microstrip Patch Resonator Filters for Mobile Communication,” International Journal of Future Generation Communication and Networking, Vol. 9, No. 5, pp. 131-142, (2016). [13] V.S. Kushwah, G.S. Tomar and S.S. Bhadauria, “Performance Comparison of Microstrip Band-Reject Filters for Different Dielectric Materials,” International Journal of Future Generation Communication and Networking, Vol. 9, No. 10, pp. 209-216, (2016).
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