The microstrip patch antenna with the advantages of low cost and easy installation is suitable for use in communication systems. but it has the disadvantage of having a narrow bandwidth, low gain, etc. These disadvantages make them unsuitable for application in the ultra-wideband (UWB) or millimeter...
The microstrip patch antenna with the advantages of low cost and easy installation is suitable for use in communication systems. but it has the disadvantage of having a narrow bandwidth, low gain, etc. These disadvantages make them unsuitable for application in the ultra-wideband (UWB) or millimeter wave (mmWave) bands. To solve this problem, by applying metamaterials with electromagnetic characteristics that do not exist naturally in the antenna, the performance (high gain, notch characteristics, wideband, etc.) suitable for UWB or mmWave bands can be improved. Thus, this thesis presents the performance improvement of microstrip patch antennas using metamaterial characteristics.
First, the design of a UWB antenna with quadruple band notch characteristic using negative permittivity unit cells is presented. Quad notched band characteristics are achieved at desired frequency bands by etching four complementary split ring resonators (CSRRs) on the modified rectangular patch, which is then validated by experimental results. The antenna has impedance bandwidth for voltage standing wave ratio (VSWR) < 2 from 2.85–11.52 GHz, with a notched band characteristic in the sub-6 GHz 5G (3.39–3.82 GHz), IEEE 802.11a WLAN at 5.2 GHz (5.13–5.40 GHz), IEEE 802.11a WLAN at 5.8 GHz (5.71–5.91 GHz), and ITU 8 GHz (7.5-8.61 GHz) signal bands. Furthermore, the antenna has a compact overall size of 40×30×0.81 mm3 with a stable radiation pattern, and the antenna has a lower band error than the existing antenna and satisfies the frequency of the desired notch band.
Next, the gain improvement of a microstrip patch antenna using two metamaterials with double negative (DNG) characteristic for mmWave applications is presented. The narrow bandwidth and low gain of microstrip patch antenna are improved using vertically coupled split ring metaplate (VCSRM) by periodically arranging split rings on the front and back sides of a dielectric slab. Numerical and experimental results show that the proposed antenna attains good radiation pattern, a high gain of 11.94 dBi, and a measured fractional bandwidth covering 26.58 GHz – 29.31 GHz (9.77 %). The gain of the antenna is increased by 5.35 dBi and the bandwidth is improved by 3.87 % when compared to microstrip patch antenna without VCSRM.
Moreover, to improve the performance of the proposed antenna, using double-layer concentric rings metaplate (DLCRM) is placed on the microstrip patch antennae. This is explained using the different shapes of DLCRM, and the effects of the DLCRM on the microstrip patch antennae are validated by experimental results. The proposed antenna attains a high-gain of 11.59 dBi and a bandwidth covering 27.1 GHz–29.56 GHz (8.68 %) with a small size of 18 × 22 mm2. The measurement results show that the bandwidth of the antenna with metamaterial is improved by 2.04 %, and broadside gain is increased by 4.69 dBi compared to the microstrip patch antennae without a DLCRM. Thus, the proposed antennas are suitable candidates for mmWave applications and demonstrate better performance over MIMO, metasurface, metamaterial, and array antenna with its high gain and small size.
The microstrip patch antenna with the advantages of low cost and easy installation is suitable for use in communication systems. but it has the disadvantage of having a narrow bandwidth, low gain, etc. These disadvantages make them unsuitable for application in the ultra-wideband (UWB) or millimeter wave (mmWave) bands. To solve this problem, by applying metamaterials with electromagnetic characteristics that do not exist naturally in the antenna, the performance (high gain, notch characteristics, wideband, etc.) suitable for UWB or mmWave bands can be improved. Thus, this thesis presents the performance improvement of microstrip patch antennas using metamaterial characteristics.
First, the design of a UWB antenna with quadruple band notch characteristic using negative permittivity unit cells is presented. Quad notched band characteristics are achieved at desired frequency bands by etching four complementary split ring resonators (CSRRs) on the modified rectangular patch, which is then validated by experimental results. The antenna has impedance bandwidth for voltage standing wave ratio (VSWR) < 2 from 2.85–11.52 GHz, with a notched band characteristic in the sub-6 GHz 5G (3.39–3.82 GHz), IEEE 802.11a WLAN at 5.2 GHz (5.13–5.40 GHz), IEEE 802.11a WLAN at 5.8 GHz (5.71–5.91 GHz), and ITU 8 GHz (7.5-8.61 GHz) signal bands. Furthermore, the antenna has a compact overall size of 40×30×0.81 mm3 with a stable radiation pattern, and the antenna has a lower band error than the existing antenna and satisfies the frequency of the desired notch band.
Next, the gain improvement of a microstrip patch antenna using two metamaterials with double negative (DNG) characteristic for mmWave applications is presented. The narrow bandwidth and low gain of microstrip patch antenna are improved using vertically coupled split ring metaplate (VCSRM) by periodically arranging split rings on the front and back sides of a dielectric slab. Numerical and experimental results show that the proposed antenna attains good radiation pattern, a high gain of 11.94 dBi, and a measured fractional bandwidth covering 26.58 GHz – 29.31 GHz (9.77 %). The gain of the antenna is increased by 5.35 dBi and the bandwidth is improved by 3.87 % when compared to microstrip patch antenna without VCSRM.
Moreover, to improve the performance of the proposed antenna, using double-layer concentric rings metaplate (DLCRM) is placed on the microstrip patch antennae. This is explained using the different shapes of DLCRM, and the effects of the DLCRM on the microstrip patch antennae are validated by experimental results. The proposed antenna attains a high-gain of 11.59 dBi and a bandwidth covering 27.1 GHz–29.56 GHz (8.68 %) with a small size of 18 × 22 mm2. The measurement results show that the bandwidth of the antenna with metamaterial is improved by 2.04 %, and broadside gain is increased by 4.69 dBi compared to the microstrip patch antennae without a DLCRM. Thus, the proposed antennas are suitable candidates for mmWave applications and demonstrate better performance over MIMO, metasurface, metamaterial, and array antenna with its high gain and small size.
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