Quasi Yagi-Uda Antenna Research Articles

Graphene load for harmonic rejection and increasing the bandwidth in Quasi Yagi–Uda array THz antenna for the 6G wireless communication

The THz array antenna is necessary for many applications such as the 6G satellite communication for the next generation of cell phone services. In this type of antenna increasing the bandwidth and harmonic rejection is vital. In this paper, a novel substrate integrated waveguide (SIW) Quasi Yagi–Uda antenna is suggested with a high Q-factor of 573 for 0.482 THz, and the photonic band-gap structure is also added for amending the antenna Q-factor and reduces the side-lobe level. Basic studies show the effect of SIW formation and PBG on the Q-factor and gain of this antenna. However, arraying and adding a power divider can impact the antenna return loss and increasing the harmonic or resonance in other frequencies which is not interesting in real antennas. Therefore, a THz filter based on the graphene load is added between the power divider and the array antenna to reduce the return loss in harmonic and increasing the bandwidth of the antenna to 15.2 % and the total gain of the antenna is 9.07 dB with a directive pattern and side-lobe level of −5 dB. As a result, the graphene load in the power dividers can be used for omitting unwilling harmonic in the array structure.

Via-Monopole Based Quasi Yagi-Uda Antenna for W-Band Applications using Through Glass Silicon via (TGSV) Technology

This paper presents a W-band planar type via-monopole based quasi Yagi-Uda antenna using metal coated through glass silicon via structures. The antenna was designed and fabricated on 350 μm thick borosilicate glass substrate, which has very low dielectric loss compared with silicon at millimeterwave frequencies. We used a microstrip line to feed the antenna, and the Yagi-Uda configuration using via structured radiator; reflectors; and director were fabricated using tungsten coated silicon via structures embedded in reflowed glass substrate with good high frequency characteristics. The proposed antenna achieved vertical polarization in planar configuration with height 0.09λo. High gain with end-fire radiation was achieved due to the Yagi-Uda configuration. Measured results confirmed the fabricated antenna operated in the W-band with 10 dB fractional bandwidth (FBW) of 12.5% from 76.3 to 86.5 GHz and peak gain of 7.82 dBi at 81 GHz in the end-fire direction. Thus, the proposed antenna with end-fire radiation will be useful for millimeter-wave onboard wireless communication, radar imaging, and tracking applications.

Compact and wide-band Quasi Yagi-Uda antenna based on periodic grating ground and coupling method in terahertz regime

We are supposed to design a compact antenna and improve the bandwidth of a planar Quasi Yagi-Uda Antenna in the Terahertz band by the periodic ground layer and parasitic metamaterial elements. For these goals, we suggest the grating structure for the ground plane to dispense the current of the antenna to attain higher impedance matching and two concentric rectangular parasitic loops are used to improve it. The ground plane is altered to improve bandwidth enhancement and provide size reduction. In this structure, a dipole driver is exploited on both sides of a transparent glass with refractive index of 1.95 and thickness of 1 μm as the substrate, and a microstrip-line is utilized for feeding the dipole element. The structure is optimized by parametric studies and parameters for the best performance are presented for achieving higher bandwidth. We compact this antenna size more than 42.2 % in comparison normal antenna while the bandwidth is achieved more than 27 % at 1.84–2.42 THz. Thus, this antenna can be used for various applications in the THz spectrum such as the medical imaging and THz communication systems for early skin cancer.

Tunable Bandpass-to-Bandstop Quasi-Yagi–Uda Antenna With Sum and Difference Radiation Patterns

A design of the double-element E-plane quasi-Yagi–Uda antenna is proposed offering two different radiation patterns and reconfigurable bandpass-to-bandstop frequency-tunable responses. The double-element antenna covers a wide frequency range that is exploited for the realization of the tunable operation modes. This is achieved by the integration of a pair of bandpass-to-bandstop filters, each of which can be reconfigured using two varactor diodes and one p-i-n diode. The p-i-n diode serves the function of switching between bandpass and bandstop states, and the varactors facilitate the frequency tunability for both states of operation. The bandpass filter provides a continuous frequency tuning function with a minimum rolloff rate of 57 dB/GHz and out-of-band transmission coefficient −1 dB. Importantly, the reconfigurable filtering functionality of the two-element antenna is preserved when fed by a wideband hybrid coupler to produce both the sum and difference radiation patterns. To obtain a high beam symmetry, the antenna elements are fed by the difference ( $\Delta $ ) signal to produce the directive radiation pattern and they are fed by the sum ( $\Sigma $ ) port to produce the null in the main radiation direction. The experimental results validate this concept with a measured tunability of 50.0% for the bandpass state and 50.4% for the bandstop state.

Millimeter‐wave antenna with wide‐scan angle radiation characteristics for MIMO applications

A three-element quasi Yagi-Uda antenna array with printed metamaterial surface generated from the array of uniplanar capacitively loaded loop (CLL) unit-cells printed on the substrate operating in the band 25-30 GHz is proposed. The metamaterial surface is configured to provide a high-refractive index to tilt the electromagnetic (EM) beam from the two dipole antennas placed opposite to each other. The metamaterial region focuses the rays from the dipole antenna and hence increases the gain of the individual antennas by about 5 dBi. The antenna elements are printed on a 10 mil substrate with a center to center separation of about 0.5 λ 0 at 28 GHz. The three-element antenna covers 25-30 GHz band with measured return loss of 10 dB and isolation greater than 15 dB between all the three ports. The measured gain of about 11 dBi is achieved for all the antenna elements. The three antenna elements radiate in three different directions and cover a radiation scan angle of 64°.

Beam-Scanning Microstrip Quasi-Yagi–Uda Antenna Based on Hybrid Metal-Graphene Materials

In this letter, a beam-scanning seven-element microstrip quasi-Yagi–Uda antenna working at terahertz (THz) frequencies is presented. This antenna is printed on the surface of a silicon dioxide substrate. The directing elements are made from metal and extended to the length of the reflecting element by graphene. Metal and graphene strips are printed on the bottom of the dielectric substrate. The $H$ -plane radiation pattern of the quasi-Yagi–Uda antenna can be deflected from −70° to 70° by controlling the bias voltage of graphene on the upper and lower substrate surfaces. The proposed antenna configuration has potential applications in THz beam-scanning antennas.

Design equations for the Quasi Yagi-Uda antenna operating in the UHF band

Design equations for the standard Quasi Yagi-Uda antenna built on 60 mil FR4 are presented to be used on fixed wireless telecommunication systems, Wi-Fi, WiMAX and LTE. In this work, the design equations are systematically proposed for the band between 1 GHz and 3 GHz, where relative bandwidth is better than 39%, the cross-polarization is lower than - 15dB for every angle and frequency, the cross-polarization is lower than -25dB in the main lobe and a front to back ratio better than 12dB in all the bandwidth. Three antennas where designed, built and measured with the proposed equations at 1.5GHz, 2GHz and 3 GHz, showing good agreement with the simulation results.

Multi-Objective Design Optimization of Planar Yagi-Uda Antenna Using Physics-Based Surrogates and Rotational Design Space Reduction

A procedure for low-cost multi-objective design optimization of antenna structures is discussed. The major stages of the optimization process include: (i) an initial reduction of the search space aimed at identifying its relevant subset containing the Pareto-optimal design space, (ii) constructionusing sampled coarse-discretization electromagnetic (EM) simulation dataof the response surface approximation surrogate, (iii) surrogate optimization using a multi-objective evolutionary algorithm, and (iv) the Pareto front refinement. Our optimization procedure is demonstrated through the design of a planar quasi Yagi-Uda antenna. The final set of designs representing the best available trade-offs between conflicting objectives is obtained at a computational cost corresponding to about 172 evaluations of the high-fidelity EM antenna model.

A New Broadband Quasi Yagi–Uda Antenna With an EBG-Truncated Ground Plane

The design of a new broadband quasi Yagi-Uda antenna is presented. The antenna is composed of an electromagnetic band-gap (EBG)-truncated ground plane and a feeding network formed by a Marchand balun and a coupling network. The quasi Yagi-antenna was designed to work at a central frequency of 3.5 GHz using a 30-mil FR4 substrate. The simulated and measured results show a relative bandwidth better than 53%, a cross polarization lower than -19 dB in the main lobe, and a front-to-back ratio better than 12 dB in the entire bandwidth.

Broadband Planar Antenna Combining Monopole Element with Electromagnetic Bandgap

New structure of broadband planar antenna, combining monopole elements with electromagnetic bandgap (EBG) structures, is proposed. The antenna has a simple single layer structure and unique beam pattern. Antenna is fabricated on a surface of a single layer dielectric substrate and back side of the substrate is covered with metal layer. At the center of the substrate, an inverted L monopole strip is fabricated and on both sides of this monopole, EBG unit cells are placed. By tuning monopole length and EBG bandgap frequency, the monopole resonates even if metal layer exists close to the monopole radiator. Three types of EBG, one dimensional (1D), square two dimensional (2D) and hexagonal 2D, are tested. By combining monopole strip with hexagonal 2D-EBG, the bandwidth of prototype antenna, whose return loss is less than 10dB, is 840MHz in 5GHz band. To control beam patterns of antenna, parasitic elements are placed close to the monopole radiator and EBGs. These parasitic elements work as directors of quasi Yagi-Uda antenna and radiation gain at lower tilt angles is improved.