Increasing radiation power in half width microstrip leaky wave antenna by using slots technique

<p class="Default">The radiation power in the endfire is decreased while the main beam of half substrate integrated waveguide scan from broadside to endfire in a forward. The design of half-width microstrip leaky-wave antenna (HW-MLWA) has been presented in this work to increase the power radiation near endfire by using the slots technique in the radiation element. This slot leads to a decrease the cross-polarization. The proposed design comprises one element of HW-MLWA with repeated meandered square slots in the radiation element. One aspect of this antenna is generated by using a half substrate integrated waveguide with a full tapered feed line. The proposed antenna was terminated by load of 50 Ω, and feed on the other end of the antenna. Finally, the suggested design is simulated and acceptable results were found. The released gain is increased from 10.6 dBi to 12 dBi at 4.3 GHz. This design is suitable for unmanned aerial vehicle UAVs at C band application.</p>

Reflective and transmissive cross-polarization converter for terahertz wave in a switchable metamaterial

Utilizing the phase transition characteristic of vanadium dioxide, we present a metamaterial configuration to achieve both reflective and transmissive cross-polarization converters. When vanadium dioxide is metal, the design behaves as a reflective cross-polarization converter. It consists of metallic grating, topas spacer, and vanadium dioxide film. Polarization conversion ratio is more than 90% in the frequency range from 4.80 THz to 13.13 THz. When vanadium dioxide is insulator, the design behaves as a transmissive cross-polarization converter using cascaded metallic gratings with rotation angle . High-efficiency broadband cross-polarization wave conversion is achieved in the frequency band of 0.50-4.75 THz. The effects of oblique incidence on reflective and transmissive modes are studied on polarization conversion. The results tell that cross-polarization conversion is better when incident angle is in the range of -. The designed metamaterial may have a certain inspiration for the research of terahertz multifunctional polarization converter.

Compact line source generator for feeding continuous transverse stub arrays

Based on a substrate integrated lens (SIL), a compact line source generator (LSG) for feeding continuous transverse stub (CTS) arrays with linear-polarized (LP) beam scanning and dual-polarized (DP) operations is presented in this paper. The SIL consists of metamaterial cells with different sizes being arranged as concentric annulus and is printed on the center surface of two substrate layers. The SIL can convert the cylindrical wave generated by the feed probe of SIW-horn to the planar wave for feeding the CTS array. This rotationally symmetric SIL can be used conveniently to design LSG for feeding CTS arrays with the continuous beam scanning and DP operations, which has been verified by the fabrications and measurements. By simply rotating the SIW-horn along the edge of SIL, the 10-element LP-CTS array obtains a measured beam scanning range of ±35° with the highest gain of 20.6 dBi. By setting two orthogonal SIW-horns at the edge of the proposed SIL, the nine-element DP-CTS array with orthogonal radiation stubs is excited. The DP array obtains the gain of 20.3 dBi at the center frequency with the isolation of 28 dB and the cross-polarization level <−25 dB.

An approach to the evaluation of mutual resistances of vibrators in the construction of a logoperiodic antenna of double polarization

В данной работе приведены результаты теоретического исследования взаимного влияния двух вибраторов, произвольно ориентированных в пространстве. Авторы на основе метода наведенных ЭДС определили касательную составляющую электрического поля, создаваемого одним из вибраторов в месте расположения второго. С использованием данного выражения авторы предложили три способа оценки взаимного сопротивления системы двух скрещенных симметричных вибраторов. Сравнив способы по точности вычислений и затрачиваемому машинному времени, авторы выделили один из предложенных способов для проведения модельных исследований. Особенностью предложенного способа является возможность обобщения расчетного выражения не только для случая скрещенных вибраторов, но и для случаев вибраторов, расположенных в параллельных плоскостях и перпендикулярных одной и той же прямой. Поскольку указанные случаи охватывают все возможные варианты взаимной ориентации вибраторов в конструкции логопериодической антенны двойной поляризации, то предложенный подход может быть использован при проведении модельных исследований направленных свойств логопериодической антенны и оценки уровня кросс-поляризации. The results of two arbitrarily oriented in space vibrators mutual influence theoretical study are presents in this paper. Based on the method of induced EMF, the authors determined the tangential component of the electric field created by one of the vibrators at the location of the second one. Using this expression, the authors proposed three ways to evaluate the mutual resistance of a system of two crossed symmetrical vibrators. Comparing the methods by the accuracy of calculations and the machine time spent, the authors identified one of the proposed methods for conducting model studies. A feature of the proposed method is the possibility of generalizing the calculated expression not only for the case of crossed vibrators, but also for the cases of vibrators located in parallel planes and perpendicular to the same straight line. Since these cases cover all possible variants of mutual orientation of vibrators in the construction of a logoperiodic antenna of double polarization, the proposed approach can be used in conducting model studies of directional properties of a logoperiodic antenna and assessing the level of cross-polarization.