A Wideband Circularly Polarized Antenna Based on Anisotropic Metamaterial

This paper presents a novel circularly- polarized (CP) antenna based on an anisotropic metamaterial. The antenna is capable of performing linear-to-circular polarization conversion over a wideband of frequencies in the X-band (8-12GHz). The proposed antenna was constructed from a metamaterial-based polarizer mounted above the aperture of a rectangular waveguide. The polarizer was oriented at 45 degrees to E-plane of the waveguide. The proposed polarizer is composed of multiple metamaterial layers. The unit cell of the proposed polarizer consists of a single dielectric slab incorporating a series of rectangular split ring resonators that are printed on both sides of the slab. Impedance matching layers (IML) are introduced to enhance the Axial-ratio (AR) bandwidth. The polarizer has a low profile in terms of electrical length (thickness of 0.41 λ0, where λ0 is the free-space wavelength at 10.5 GHz). A full-wave electromagnetic simulator was used to verify the anisotropic characteristics of the unit cell. This was achieved by showing that the metamaterial exhibits two different refractive indices along the orthogonal components of the incident electric field. The prototype of the proposed design is fabricated and measured to validate the performance. The measured results agree with the simulated ones and demonstrated a wide impedance bandwidth of 62.4% ranging from 7.08 GHz to 13.5 GHz with a 3dB AR bandwidth of 29.9% (9.25-12.5 GHz)

Dual-Layer Corrugated Plate Antenna

This letter presents a subwavelength slot-fed high-gain dual-layer corrugated plate antenna for X-band applications. The antenna is realized by placing a second corrugated layer that has three radiating slots on top of the traditional corrugated plate antenna. The addition of the second layer improves the gain and bandwidth of the proposed antenna. Compared to a traditional single-layer corrugated plate antenna, the proposed dual-layer antenna has higher gain, lower sidelobe level, narrower half-power beamwidth, and better impedance bandwidth. A prototype of the proposed antenna is built and tested, and the measured results show that the antenna has a peak gain of 16.3 dBi at 11.3 GHz. The gain of the proposed antenna has been improved by more than 4 dBi due to coupling more energy to the second layer's three slots. Finally, the operating principles of the proposed antenna are also discussed and analyzed thoroughly

A Reconfigurable Microstrip Patch Antenna with Switchable Liquid-Metal Ground Plane

This letter presents a novel reconfigurable microstrip patch antenna that is reconfigured using liquid metal. The proposed antenna employs two approaches in unison to switch the direction of the main beam. Specifically, the antenna uses the parasitic steering approach together with a novel switchable ground plane. The antenna operates at 5.9 GHz. It consists of a driven patch surrounded by four parasitics. All five elements are circular disk resonators. Each of the parasitic resonators incorporates a drill hole. The drill holes can be filled or emptied of liquid metal to control the behavior of the parasitics. The ground plane incorporates two reconfigurable segments. The switchable ground plane can be reshaped by adding or removing the additional segments of ground plane which are formed from liquid metal. To the best of the authors' knowledge, this is the first antenna that is capable of reconfiguring its radiation pattern by reshaping the ground plane using liquid metal. A hardware prototype of the antenna was fabricated and measured. The measurement results show that the antenna can switch between five different beam directions, namely: 0°, ±20°, and ±40°. The design has only 0.5 dB of scan loss across the beam switching range

Continuous Beam Steering Realized by Tunable Ground in a Patch Antenna

A continuously steerable patch antenna employing liquid metal is presented. The proposed antenna employs a novel tunable ground plane together with parasitic steering to steer the direction of the main beam. The tunable ground plane consists of a permanent region, made from copper, and two tunable regions formed from liquid metal. The liquid metal channels were fabricated using 3D printing technology. By continuously injecting liquid metal into channels, the proposed patch antenna can provide continuous beam steering from -30 to +30 in the elevation plane, while achieving low side lobe level performance combined with low scan loss performance. Such an approach has never been tried before and it is only possible due to the unique properties of liquid metal. To the best of the authors’ knowledge, this is the first time that tunable ground plane has been used for a patch antenna to achieve continuous beam steering. The proposed antenna operates at 5.3 GHz. The antenna is fabricated and measured. Measurement results agree well with the simulation results and validate the effectiveness of the proposed beam steering technique. The proposed antenna has a measured gain of 8.1 dBi at 5.3 GHz and wide bandwidth performance. The tunable ground technique proposed in this work will find numerous applications within future wireless communications systems

10 GHz Low Loss Liquid Metal SIW Phase Shifter for Phased Array Antenna

This paper presents a proof of concept demonstrator for a pair of novel phase shifters based on substrate integrated waveguide (SIW) technology. Gallium-based liquid metal (LM) is used to reconfigure each phase shifter. The paper presents LM phase shifters that, for the first time, have a phase shifting range of 360⁰. The phase shifters have a small electrical size, and they are intended for use within phased array antenna applications. The paper also presents a design procedure for the phase shifters. The procedure has been used to design two phase shifters operating at 10 GHz. The design process can be readily scaled for operation at other frequencies. The proposed phase shifters are reciprocal and bidirectional and they have very low insertion loss. A series of reconfigurable LM vias are used to achieve the phase shift. Each of LM via is activated once a drill hole is filled with LM and it is deactivated once LM is removed. Using this method; it is possible to achieve a phase shift step ranging from 1° to 100° using a single LM via. Moreover, the overall phase shift can be extended to 360° by employing several LM vias in series inside the SIW. The proposed phase shifters have an insertion loss lower than 3 dB and provide a total phase shifting range of approximately 360° in eight steps of approximately 45° each. This enables the proposed two phase shifters to have an extraordinary Figure of Merit (FoM) of 131.3 ⁰/dB and 122.4 ⁰/dB

Evaluating the performance of some Primitive Wheat Triticum dicoccum Genotypes

Seven wheat genotypes (Triticum dicoccum) and the local check sham5 variety were planted during  growing season 2010/2011under rainfed conditions using RCBD with three replications. Yield components (number of total and fertile tillers, number and weight of grains per spike, weight of thousand grain and individual plant grain yield) were studied in two sites in order to define the differences between the studied genotypes in both sites and to provide the superior genotypes for breeding programs. Results showed that the genotype PW70 was significantly superior in (grain yield, number and weight of grain per spike) comparing to check. While, the genotypes (PW96, PW119, PW123) were significantly superior in thousand grain weight comparing to check, as well as the genotype (PW81, PW127) were significantly superior in total and fertile tillers number comparing to check. Most traits were significantly superior in Al-Ghab site

Correlation, Regression and Path analysis among yield and yield traits in Triticum dicoccum

Seven wheat genotypes (Triticum dicoccum) and the local check sham5 were planted all at Al-Ghab and Izra Research centers in The General Commission for Scientific Agricultural Research in Syria during growing season 2010/2011. Yield components (number of total and fertile tillers per plant, number and weight of grains per spike, weight of thousand grain and individual plant grain yield) were studied in two sites in order to predict their effect and to determine their effects on grain yield in order to define selection criteria for grain yield. Results revealed all studied traits except total tillers number were positively correlated with grain yield, and only (fertile tillers number and grain number per spike and grain weight per spike) had a significant regression with grain yield and these traits can explain about (27.6, 67.7, 62.2)% respectively of the variation final grain yield. Results of path analysis indicated that the direct effect of fertile tillers per plant and grain weight per spike on grain yield was positive and high (0.6178, 0.7563) respectively, so that we can depend on them in breeding program as selection criteria to increase grain yield in plant

Compact and Low-Cost 3-D Printed Antennas Metalized Using Spray-Coating Technology for 5G mm-Wave Communication Systems

This letter presents a design of two compact, light, rigid, and low-cost three-dimensionally (3-D) printed millimeter-wave antennas for a fifth-generation (5G) communication system. The proposed antennas consist of a radiating slot that is surrounded by a rectangular cavity and corrugations, which boost the gain performance of the antennas. Furthermore, the proposed antennas are fabricated using 3-D printing technology, and they are metalized using novel, simple, and low-cost techniques, which utilize the commercial conducive spray-coating technology. The proposed antennas operate at a 28 GHz band, where the first design is fed by a waveguide to prove the performance, whereas the second design is fed by a microstrip line to demonstrate the ability to be integrated into a compact structure. Measurement results show a wide impedance bandwidth, which enables the proposed antenna design to be a strong candidate for 5G applications

mm-Wave Low Insertion Loss SIW Phase Shifter Based on Liquid Metal Technology

This paper presents proof of concept of first liquid metal (LM) based millimeter-wave (mm-wave) phase shifter that have very low insertion loss (IL) performance. The proposed phase shifter has a phase shift up to 360° with a phase resolution of 45°. The phase shifter operate on 26GHz 5G band and have IL performance of lower than 2.1dB. This enables the proposed phase shifters to have an excellent figure of merit (FoM) of 174.7°/dB at 26GHz. The proposed phase shifter has several advantages including the capability to be integrated with SIW based feeding network for mm-wave phased array antennas. The phase of the phase shifters is controlled by introducing vias formed of LM. When the via is required, the via hole is filled with LM and when the via is no longer required, the holes are emptied of LM. The proposed reconfiguration approach will be also applicable within a wide range of different reconfigurable mm-wave devices

Liquid Metal mm-Wave Phased Array Antenna for 5G Wireless Communication

This paper presents a mm-wave phased array antenna enabled by Liquid Metal technology. The proposed mm-wave phased array antenna operate on 26 GHz band and it is intended for 5G wireless applications. The proposed array consists of 1 × 4 array of printed dipole antennas with reconfigurable directors consisting of Liquid metal. The proposed array combines two different beam steering concepts to maximize the beam steering angle and the gain of the array with minimum number of elements; while keeping the side lobe level (SLL) performance low. These two concepts are reconfigurable one through using liquid metal directors rotation and electronic one through using phased shifters. The proposed array resonates at 26 GHz with a wide bandwidth performance and beam steering angle up ±40° in the end fire direction with gain performance exceeds 12.6 dBi