A complementary Sierpinski gasket fractal antenna array integrated with a complementary Archimedean defected ground structure for portable 4G/5G UWB MIMO communication devices

Abstract

This article presents the design, development, and experimental validation of an aperture coupled complementary Sierpinski gasket equilateral triangular fractal antenna array for portable 4G/5G UWB communication devices. The proposed antenna array is printed on two FR-4 substrate layers (ε r = 4.4, height = 1.57 mm, and tan δ = 0.024) with two fractal triangular patches on the top layer (separated by a distance of 3λ/2) and feed network on the bottom layer of FR-4. The fractal patches (optimized up to second order of iteration) are fed using an aperture-coupled feeding mechanism, where the aperture slots in the ground layer are modified to complementary Archimedean spiral slots which are interconnected by a modified "X" shaped slot to improve the impedance matching at the operational bands. The proposed array has overall volumetric dimensions of 41 × 99.4 × 3.245 mm 3 and provides a size reduction of 46% for the metallic area using the fractal geometry. The proposed array shows a simulated UWB response from 4.3 to 11.6 GHz (fractional bandwidth of 91.8% at 7.95 GHz) with a simulated peak gain of 4.7 dB (at 9.2 GHz) and port-to-port isolation of ≤−15.8 dB for the entire band. For validation of simulated responses, the proposed array is fabricated and tested for S-parameters (S 11 , S 22, S 12 , and S 21 ). A measured impedance bandwidth of 6.3 GHz is observed for a frequency band from 5.7 to 12 GHz. Two additional frequency bands are also exhibited by the array from 4.1 to 4.25 GHz and 4.7 to 5.3 GHz. The array diversity parameters such as envelope correlation coefficient (≤0.007 [simulated], ≤0.0057 [measured]), diversity gain (≥9.999 [simulated], ≥9.971 [measured]), mean effective gain (≥−3.9 dB [simulated], ≥−5.1 dB [measured]), and channel capacity loss, (≤0.37 bits/s/Hz [simulated], ≤0.4 bits/s/ Hz [measured]) which are calculated using the simulated and measured S-parameters of the array are also observed. These parameters allow the proposed fractal array to be implemented in a diversity combining technique to improve the overall SNR and hence support a high data rate for 4G/5G multimedia services. K E Y W O R D S aperture coupled feed, complementary Archimedean spiral, complementary Sierpinski gasket fractal, multiple-input multiple-output (MIMO), UWB

A novel modified Kock–Snowflake fractal MIMO antenna for 4G/5G UWB communication gadgets

“…Given the confined space inside the handheld devices, the array with tightly‐packed multiple antennas will gradually increase the interelement coupling and envelope correlation coefficient (ECC), which deteriorates the array's diversity operation 2 . Therefore, it is desirable to introduce self‐similar and space‐filling fractals like Sierpinski gasket, 3 Pythagorean tree, 4 Koch curve, 5 and so forth in compact multiport antennas to generate multi/wideband response and also aids in improving interport isolation 6 . Based on the scholarly research, isolation of the UWB array can be enhanced by several techniques like quasi‐self‐complementary structures, 7 metamaterial, 8 parasitic element, 9 neutralization line, 10 defected ground structures (DGS), stubs, 11 and so forth.…”

A Compact U-Shaped Uwb-Mimo Antenna With Novel Complementary Modified Minkowski Fractal for Isolation Enhancement

“…Many fractal UWB-MIMO antennas have been reported in the past [13][14][15][16][17][18][19][20][21][22]. Koch [13], selfsimilar [14], complementary Sierpinski gasket [15], modified Sierpinski carpet [16], and hybrid Sierpinski Koch [17] shaped two-element fractal monopole UWB-MIMO antennas are reported in [13][14][15][16][17]. Koch [18], hexagonal molecule shaped [19], and Sierpinski Knopp [20] shaped four-element fractal monopole UWB-MIMO antennas are reported in [18][19][20].…”

Computational analysis of a dual‐port semi‐circular patch antenna combined with Koch curve fractals for ultra‐wideband systems

“…In Reference 17, a 41 × 99.4 mm 2 aperture-coupled-fed complementary Sierpinski gasket fractal array integrated with two modified complementary Archimedean spiral-shaped DGS is reported to cover a wide operational range from 4.3 to 11.6 GHz (91.8% FBW) with S 21 /S 12 ≤ −15.8 dB and ECC ≤0.007. All the aforementioned fractal MIMO antennas [12][13][14][15][16][17] occupy a large surface area with a low degree of inter-port isolation, therefore, they cannot be considered as a good choice for the implementation in the modern portable electronic gadgets, functioning in a highly scattered surrounding. Also, some of the reported MIMO antennas 16,17 covers the frequency band outside the FCC's allocated UWB band, which can further give rise to interference problems.…”

“…All the aforementioned fractal MIMO antennas [12][13][14][15][16][17] occupy a large surface area with a low degree of inter-port isolation, therefore, they cannot be considered as a good choice for the implementation in the modern portable electronic gadgets, functioning in a highly scattered surrounding. Also, some of the reported MIMO antennas 16,17 covers the frequency band outside the FCC's allocated UWB band, which can further give rise to interference problems. Table 1 presents the shortcomings of the formerly investigated UWB-MIMO antennas as compared to the proposed fractal MIMO antenna.…”

“…With the goal of solving the trade-off among the high operational bandwidth, antenna compactness and good inter-port isolation characteristics, [12][13][14][15][16][17][18][19][20][21][22] a 2 × 2 miniaturized Koch curve fractal MPA array with a higher operational range and significant diversity performance is presented in this research. The proposed fractal array is modeled on a 1.57 mm thick FR-4 lossy substrate with relative permittivity ( r ) and loss tangent (tan ) of 4.4 and 0.024 respectively.…”