Microsoft Word - ETASR_V12_N5_pp9166-9171 Engineering, Technology & Applied Science Research Vol. 12, No. 5, 2022, 9166-9171 9166 www.etasr.com Sarade & Ruikar: Development of a Wide Bandwidth Massive Eight Dissimilar Radiating Element … Development of a Wide Bandwidth Massive Eight Dissimilar Radiating Element Multiband MIMO Antenna for mm-Wave Application Shrenik Suresh Sarade Electronics Engineering Walchand College of Engineering Sangli, India shreniks2k7@rediffmail.com Sachin D. Ruikar Electronics Engineering Walchand College of Engineering Sangli, India sachin.ruikar@walchandsangli.ac.in Received: 10 June 2022 | Revised: 26 July 2022 | Accepted: 28 July 2022 Abstract-This paper proposes a massive MIMO antenna operating on 6GHz frequency as millimeter-wave. It consists of eight dissimilar-shaped radiating elements. The radiating element of the antenna is designed using square shape with different cut slots. Parasitic elements and defected ground structure are introduced for the enhancement of the correlation coefficients and total active reflection coefficients of the MIMO antenna. The rectangular shape parasitic elements are placed between the square radiating patches. The ground plane consists of rectangular shape defected ground structures. The antenna is constructed on the FR-4 substrate. Parameters such as isolation, cross-correlation, and bandwidth are enhanced. The obtained through simulations antenna parameters values of return loss, isolation, cross-correlation, total active reflection coefficients, and bandwidth are less than -10dB, less than -9.30dB, less than 0.16, less than 0.00015, and greater than 200MHz respectively. The antenna operates on various bands with fractional bandwidth greater than 3% for a frequency of 6GHz. This antenna is useful for a variety of applications in wireless systems. Keywords-MIMO; DGS; TARC; CC;ECC I. INTRODUCTION Antennas are a crucial part of communication systems. An antenna is used to transport data from one location to another without interfering with the original signal. As a result, there is a need to build an antenna that meets the requirements of the communication system, such as size, weight, and signal quality. Multiple Input and Multiple Output (MIMO) antennas play an important role in the antenna field nowadays. Multiple antennas may be present at the transmitter and the receiver. The low data rate in Single Input and Single Output (SISO) system can be improved using an MIMO antenna system. The data rate of MIMO antenna grows linearly and depends on the number of patches in the antenna. The performance of the MIMO antenna differs with return loss, isolation, correlation coefficients, and total active reflection coefficients. In a MIMO antenna, multiple radiating patches are positioned on the same substrate in close proximity to one another. The close proximity of the square radiating patches influences the isolation (which becomes high) between the radiating patches and the correlation coefficients become higher. There is a requirement of improvement in antenna's isolation, correlation coefficients, and data rate. To improve isolation and correlation coefficients, several studies employ Defective Ground Structure (DGS), Parasitic Elements (PEs), metamaterials, Decoupling Structure (DS), and Electromagnetic Band Gap (EBG) approaches. A DGS technique is used to improve isolation. Cut slots of various shapes are used in the ground plane [1-6]. To improve isolation, a decoupling structure is constructed that decouples the input of radiating patches from the matching network setup in [7-11]. PEs are used to improve the isolation between the patches in [12-17]. From the above literature survey, it can be concluded that there is a requirement to develop a massive MIMO antenna that operates on wide bandwidth multiband applications, with better TARC and better cross correlation. A diverse shaped-element gigantic MIMO antenna is proposed in this work. It operates at multiband frequency with wide band operation. Parasitic elements and a defective ground structure are used to improve antenna parameters such as isolation, cross correlation, and total active reflection coefficients. II. DESIGN OF THE MASSIVE MIMO ANTENNA The concept of the MIMO antenna is explained above along with the literature survey. In this section, the massive MIMO antenna is designed and explained in detail. The designed antenna comprises of 8 square radiating patches with distinct cut slots for the 6GHz frequency, as shown in Figure 1. The antenna dimensions are provided in Figure 2. The antenna is developed using a FR-4 substrate with 1.6mm height h and 4.4 dielectric constant. The antenna's geometrical structure, i.e. length Lre and width Wre, was created using the square radiating patch transmission line model [20], which has the dimensions listed in Table I, which shows the measurements of 8 radiating elements with varying cut slots. A rectangular cut slot [20] is placed in patch-1 and patch-3, with length C and width D. A similar rectangular cut slot [20] is placed in patches-5, -7, and - 8. A square cut slot is placed in patch-6, with both length and Corresponding author: Shrenik Suresh Sarade Engineering, Technology & Applied Science Research Vol. 12, No. 5, 2022, 9166-9171 9167 www.etasr.com Sarade & Ruikar: Development of a Wide Bandwidth Massive Eight Dissimilar Radiating Element … width C. The cut slot dimensions of the single patch are optimized using the equivalent circuit explained in Section III. Inset Feed Line (IFL) [20] with length C and width D is used to excite the antenna elements (dimensions listed in Table I). The antenna's dimensions (FR-4 substrate) which consist of length E and width F of the patch are summarized in Table I. The distance between the parasitic elements and the radiating patches is less than half of the wavelength. Fig. 1. Massive MIMO antenna with 8 distinct shaped components with PEs and a GDS. Fig. 2. The dimensions of the developed massive MIMO antenna. Fig. 3. The ground plane of antenna with DGS. Engineering, Technology & Applied Science Research Vol. 12, No. 5, 2022, 9166-9171 9168 www.etasr.com Sarade & Ruikar: Development of a Wide Bandwidth Massive Eight Dissimilar Radiating Element … PEs and DGS improve the Total Active Reflection Coefficients (TARC), the Correlation Coefficient (CC), and the Envelope Correlation Coefficient (ECC) values between the radiating elements. Table I shows the size of parasitic elements (P1 to P14) [12-17]. As indicated in Figure 1, rectangular shaped Parasitic Elements (PEs) are used between the radiating patches. The PEs are used to negate parts of the coupled field between the elements because it creates an opposite coupling field, which lessens the original field and hence reduces total coupling on the antenna. The PE structure and the radiating patch are not physically related. Figure 3 depicts the antenna's ground plane, while Figure 4 depicts its dimensions. Table I shows the length D and width C of the DGS in the ground plane. The ground plane is made up of rectangular-DGS cut slots [1-6] that are utilized to improve isolation TABLE I. ANTENNA DIMENSIONS Sr. no. Parameter Dimensions (in mm) 1 Patch length (Lre) A = 11.38 2 Patch width (Lre) B = 11.38 3 Length of IFL D = 6.41 4 Width of IFL C= 2.942 5 Length of substrate E= 36.522 6 Width of substrate F= 80 III. EQUIVALENT CIRCUIT MODEL OF THE ANTENNA In this section, the operation of the single radiating patch of the antenna is explained using the equivalent circuit model. That is applicable to all radiating patches. DGS and PEs are used in the development of the gigantic MIMO antenna. These two techniques are used to improve the antenna's isolation, TARC, CC, ECC, and bandwidth. The equivalent circuit mathematical model is used to describe how antennas work. The corresponding circuit of a single radiating patch is shown in Figure 5. Fig. 4. The dimensions of the ground plane of the antenna with DGS. Fig. 5. Equivalent circuit model for square-radiating patch. As shown in Figure 1, the antenna comprises of a square radiating patch with a cut slot. Figure 5 is divided into two parts: a square shape circuit with impedance Z1 and rectangular cut slot-1 and 2 with impedance Z2 and Z3. The inductor and capacitor values of the equivalent circuit [21] are used to compute the cut slot dimensions using (1) and (2): G� � �.����� � �1 � 0.04167�k�H���� �� (1) B� � �.����� � �1 � 0.636 ln�k�H���� � (2) where G1 is the resistive value of the circuit, B1 is the capacitive or inductive value of the circuit, W= Lre the width of the patch, h the height of the substrate, and k0 constant. Because the antenna elements have distinct cut slots, the antenna can function on many frequencies. This antenna's operating concept is similar to that of any other radiating patch, and cut slots are provided according to the desired frequency. IV. RESULT ANALYSIS The antenna is simulated using the High Frequency Structure Simulator (HFSS). Isolation, CC, ECC, TARC, and bandwidth [19] are the performance parameters of the MIMO antenna. The 8 radiating patches are arranged in a row (close to each other) which results in high level of isolation among the radiating patch. DGS and PE techniques are employed to improve the isolation between the radiating patches. The rectangular carved slit acts as a DGS in the ground. The DGS alters the properties of the transmission line's inductor and capacitor, resulting in a shift in the antenna's frequency response. A rectangular shaped PE is placed between the radiating elements to improve the antenna's isolation and bandwidth. It prevents the radiating energy passing from one element to the nearby element. The isolation performance between the parameters helps improve CC, ECC, and TARC. The return loss (S11) and the acquired isolation between the remaining elements of patch-1 are shown in Figure 6. The antenna operates on 6.2GHz (m1) and 7.1GHz (m3), with less than -17.50dB return loss (S11), less than -11.25dB isolation (S12 (m2 and m4)), and 347.4MHz (5.79%) bandwidth. The isolation between the remaining patches, S13, S14, S15, S16, S17, and S18 is less than -11.25dB (S12). Fig. 6. Return loss (S11) and isolation of patch-1. The antenna element bandwidth [18-20] is obtained at - 10dB return loss. The return loss (S22) and the isolation Engineering, Technology & Applied Science Research Vol. 12, No. 5, 2022, 9166-9171 9169 www.etasr.com Sarade & Ruikar: Development of a Wide Bandwidth Massive Eight Dissimilar Radiating Element … between the remaining elements of patch-2 are shown in Figure 7. It operates on the 5.7GHz, with less than -24.79dB return loss (S22 (m1)), less than -11dB isolation (S26 (m2)), and 437.3MHz (7.289%) bandwidth. The isolation between the remaining patches such as S21, S23, S24, S25, S27, and S28 is less than -11dB (S26). The return loss (S33) and the isolation between the remaining elements of patch-3 are shown in Figure 8. It operates on 5.8GHz (m1) and 6.9GHz (m3), with less than - 12.50dB return loss (S33), less than -11.40dB isolation (S34 (m2) and m4)), and 403.32 MHz (6.72%) bandwidth. The isolation between the remaining patches such as S31, S32, S35, S36, S37, and S38 is less than -11.40dB (S34). Fig. 7. Return loss (S22) and isolation of patch-2. Fig. 8. Return loss (S33) and isolation of patch-3. Fig. 9. Return loss (S44) and isolation of patch-4. The return loss (S44) and the isolation between the remaining elements of patch-4 are shown in Figure 9. It operates on 6.1GHz (m1) and 6.7GHz (m3), with less than - 10.25dB return loss (S44), less than -9.35 dB isolation (S43 (m2 and m4)), and 488MHz (8.146%) bandwidth. The isolation between the remaining patches such as S41, S42, S45, S46, S47, and S48 is less than -9.35 dB (S43). The return loss (S55) and the isolation between the remaining elements of patch-5 are shown in Figure 10. It resonates on 5.8GHz (m1) and 6.8GHz (m3), with less than - 18.50dB return loss (S55), less than -9.70dB isolation (S51 5.8GHz (m2 and 5.8GHz m4)), and 399MHz (6.65%) bandwidth. The isolation between the remaining patches such as S52, S53, S54, S56, S57, and S58 is less than -11.33dB (S51). The return loss (S66) and the isolation between the remaining elements of patch-6 are shown in Figure 11. It resonates on 5.8GHz (m1), with less than -20.92dB return loss (S66), less than -11.17dB isolation (S67 5.8GHz (m2)), and 425.76 MHz (7.096%) bandwidth. The isolation between the remaining patches such as S61, S62, S63, S64, S65, and S68 is less than -11.33dB (S67). Fig. 10. Return loss (S55) and isolation of patch-5. Fig. 11. Return loss (S66) and isolation of patch-6. Fig. 12. Return loss (S77) and isolation of patch-7. The return loss (S77 (m1)) and the isolation between the remaining elements of patch-7 are shown in Figure 12. It resonates at 5.7GHz, with less than -16.25dB return loss (S66), Engineering, Technology & Applied Science Research Vol. 12, No. 5, 2022, 9166-9171 9170 www.etasr.com Sarade & Ruikar: Development of a Wide Bandwidth Massive Eight Dissimilar Radiating Element … less than -10.98dB isolation (S76 (m2)), and 297MHz (4.95%) bandwidth. The isolation between the remaining patches such as S71, S72, S73, S74, S75, and S78 is less than -11.33dB (S76). The return loss (S88) and the isolation between the remaining elements of patch-8 are shown in Figure 13. It resonates at 5.8GHz (m1) and 6.8GHz (m3), with less than - 20.30dB return loss (S88), less than -11.10dB isolation (S84 (m2 and m4)), and 379.2MHz (6.32%) bandwidth. The isolation between the remaining patches such as S81, S82, S83, S85, S86, and S87 is less than -11.33dB isolation (S84). Fig. 13. Return loss (S88) and isolation of patch-8. The results of the antenna parameter investigation show that the gain attained is 2.69dB, as shown in Figure 14. Figure 15 shows the antenna radiation pattern. TARC is less than 0.16, CC is less than 0.0122, ECC is less than 0.00015, and DG is near to 9.9985 [20]. Fig. 14. Gain of the MIMO antenna. Fig. 15. Radiation pattern of the MIMO antenna. V. COMPARISON The proposed antenna's parameters are compared with other works in Table II. The comparison shows that the proposed antenna is developed for 8-different shaped radiating elements. It operates on the multiband frequency with a wide bandwidth. TABLE II. COMPARISON OF THE PROPOSED ANTENNA WITH OTHER WORKS Ref Technique used Parameter Frequency band and bandwidth Radiating patches [1] DGS -10 dB RL, -12dB isolation Single band and narrow band Same shape 8-radiating patches [7] DGS -20 dB RL, -15dB isolation Dual band and narrow band Same shape 8-radiating patches [12] PE -10 dB RL, -10dB isolation Dual band and wide band Same shape 8-radiating patches Proposed DGS + PE -10 dB RL, -9.30dB isolation Multiband and wide band with better cross correlation Different 8- shaped radiating patches VI. CONCLUSION The proposed 8 dissimilarsized element antenna operates on various frequency bands for a wide bandwidth. The antenna parameters are enhanced using DGS and PEs. The proposed antenna operates at 5.7GHz, 5.8GHz, 6.1GHz, 6.2GHz, 6.7GHz, 6.8GHz, 6.9GHz, and 7.1GHz. 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