Abstract-In this paper a compact antipodal Vivaldi antenna with dimensions of 40 × 85 mm 2 for Ka band is presented. To enhance the antenna gain epsilon near zero metamaterial (ENZ) unit cells are embedded at the same plane of the Vivaldi flare aperture. These ENZ unit cells have the advantage of confining the radiated fields with additional compact size. The obtained antenna exhibits an ultra-wide bandwidth from 23 GHz to 40 GHz with a reflection coefficient less than −10 dB. This is suitable for 5G applications at both 28 and 38 GHz. The antenna gain in this frequency band is found in the range from 14 to 17.2 dBi. The proposed antenna is designed by using CST-MW Studio, and the results are verified with experimental measurements.
This paper exhibits a high-gain, low-profile dipole antenna array (DAA) for 5G applications. The dipole element has a semi-triangular shape to realize a simple input impedance regime. To reduce the overall antenna size, a substrate integrated cavity (SIC) is adopted as a power splitter feeding network. The transition between the SIC and the antenna element is achieved by a grounded coplanar waveguide (GCPW) to increase the degree of freedom of impedance matching. Epsilon-near-zero (ENZ) metamaterial technique is exploited for gain enhancement. The ENZ metamaterial unit cells of meander shape are placed in front of each dipole perpendicularly to guide the radiated power into the broadside direction. The prospective antenna has an overall size of 2.58 λg3 and operates from 28.5 GHz up to 30.5 GHz. The gain is improved by 5 dB compared to that of the antenna without ENZ unit cells, reaching 11 dBi at the center frequency of 29.5 GHz. Measured and simulated results show a reasonable agreement.
A quad-port multiple-input multiple-output (MIMO) filtenna with compact dimensions of 50 × 50 mm2 are configured, in which each element is placed orthogonally to its adjacent to enhance the isolation. The MIMO element is configured based on the novel COVID-19 virus shape with a co-planar waveguide feeding structure (CPW) and dimensions 17 × 22 mm2. The element bandwidth is ranging from 3.3 GHz to more than 60 GHz. Three frequency notches are designed at 3.5 GHz for WiMAX and 5.5 GHz for WLAN, and 8.5 GHz for X-band applications. A bandpass filter (BPF) with high out of band rejection is used as a decoupling structure (DS) to improve the isolation to more than 30 dB across most of the bandwidth. The equivalent circuit model is scrutinized to investigate the enactment of the decoupling structure. The proposed MIMO filtenna system provides an impedance bandwidth of 2.4-18 GHz, a peak gain of 13.2 dBi, and an envelope correlation coefficient (ECC) less than 0.00021. In turn, channel capacity loss does not exceed 0.2. The MIMO filtenna is fabricated and measured. Good agreement between the measured and simulation results is achieved.
This paper presents a wideband eight-port multiple-input-multiple-output (MIMO) circularly polarized antenna system for mm-wave applications. The proposed antenna element is an L-shape microstrip line with a series fishtail stubs on one side. The spacing between these stubs is adjusted to be a guided wavelength at the center frequency. These fishtail stubs are used to cancel the anti-phase magnetic currents to enhance the radiated fields from the microstrip line. A 90 • phase difference between the fields of the two arms of the L-shape is obtained by shifting the feeding point from the center of the corner by one eighth guided wavelength. This 90• phase difference introduces the required circular polarization. The proposed antenna covers the frequency range from 27.5 up to 31 GHz, which is suitable for mm-wave N261 5G-band which cover the range from 27.5 to 28.35 GHz. These antenna elements are arranged on the four corners of a rectangular substrate to configure the proposed MIMO antenna system. Different parameters of this MIMO antenna are investigated by using numerical simulation and verified by experimental results.
A design of high sensitivity Vivaldi antenna is introduced for detecting the low sugar and salt concentrations in water. The reason for selecting the Vivaldi antenna configuration is to provide two desired features; ultra-wideband and a high directivity so the surrounding clutter effect can be minimized. The prospective antenna embraces the ultra-wideband (UWB) from 4 GHz to 11 GHz. Two techniques are exploited to improve the antenna detectability; epsilon-near-zero (ENZ) metamaterial and antenna aperture amending. The ENZ metamaterial is very sensitive to the permittivity of the substrate, so any loading effect can easily alter the electric field distribution and hence affect the antenna phase properties. The high sensitivity can be increased by operating at a higher frequency. The aperture amending is used to improve substrate-air matching. An equivalent circuit model is scrutinized for further emphasis of the ENZ metamaterial operation, showing good agreement with EM simulation results. In terms of phase variation, the designed antenna is employed to sense sugar and salt in water. The amount of sugar and salt affects the material characteristics of the solution and, as a result, the reflected phases. Practical observations reveal that when the sugar and salt contents in the liquid increase, the phase falls. The simulation and measurement results of a fabricated prototype have good agreement. The time-domain analysis is discussed, revealing low distortion of received pulses.
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