변강일 교수

This communication proposes the design of a quadrifilar helix antenna (QHA) with stepped-width arms and a meander feeding network. The stepped-width arms are applied to reduce the antenna size and adjust the frequency interval for dual-band operation. The feeding network includes a 90°-hybrid chip coupler and two meander lines that are designed to give a 180°-phase delay. The proposed QHA is optimized using a genetic algorithm (GA) and then fabricated to measure its performances in a full anecho

This paper presents a systematic approach to the optimum placement of direction finding (DF) antennas in a harsh platform environment. A circular array with omni-directional elements is considered for azimuthal direction of arrival (DOA) estimation based on the multiple signal classification (MUSIC) algorithm. The element positions are optimized by the use of a genetic algorithm (GA) in conjunction with the FEKO electromagnetic simulator. The proposed approach is first tested with a generic plat

This communication proposes a curved array split into two subarrays to improve the pattern null depth and width for controlled reception pattern antenna (CRPA) systems. The proposed array consists of a single reference element at the center and two subarrays that are arranged on a spherical coverture. To consider both signal processing and electromagnetic (EM) perspectives, array patterns are calculated by using a microstrip patch antenna in conjunction with a constraint least-mean-square (LMS)

This paper proposes an optimum array configuration to improve null steering time for mobile controlled reception pattern antenna (CRPA) systems. The proposed array consists of a single reference element at the center and nine auxiliary elements arranged in a circular array. The array radius and the vertical positions of the center element are optimized using a genetic algorithm in conjunction with a constrained least-mean-square algorithm. The results demonstrate that the proposed array is suita

This communication proposes a glass-integrated antenna using a coupled feed structure for military FM radio communications on aircraft. The proposed antenna consists of a feed strip and two radiators, printed on the left-side window of the cockpit. The proposed antenna structure is optimized with the genetic algorithm in conjunction with the FEKO EM simulator. The optimized antenna is built and installed on a 1/10-sized KUH-Surion mock-up and antenna performance, such as reflection coefficient a

This communication proposes the design of an arc-shaped antenna array with high isolation to increase the null depth for controlled reception pattern antenna applications. The array is composed of three identical antennas, and each array element is transformed from a rectangular shape to an arc shape to maximize the distance between antenna edges for isolation improvement. The proposed array is fabricated on a 5.5-inch circular substrate to measure antenna characteristics in a full anechoic cham

A novel and simple approach to adjust the polarisation properties of a microstrip patch antenna in the entire axial ratio (AR) range is proposed. The proposed antenna consists of a radiating patch and a parasitic strip separated into two parts, and the separated strip is placed at the outer perimeter of the patch for capacitive coupling. This structure enables the antenna to induce opposite‐direction currents on the strip, which allows flexible polarisation adjustment by moving the separated pos

ABSTRACT This article proposes a novel feeding mechanism to improve the isolation characteristics in the GPS L1 and L2 bands for electromagnetically small arrays (aperture diameter < λ). In the mechanism, a feeding patch is sandwiched between two radiating patches and excited by two pins with a 90° phase difference. To improve the isolation, ceramic with a high dielectric constant is used as the antenna substrate, and then four identical antennas are mounted on the ground platform. The result

Abstract Emerging internet‐of‐things technologies require widespread antennas and sensors. They should be cheap enough to be widely deployed, but still should be highly functional and tunable. Here, a thorough, in‐depth study of spectral shifts and phase vortices in kirigami Fano‐resonant metamaterials is presented. Microwave metamaterials are printed on paper using metal inks. Then, the printed metamaterials are cut line‐by‐line and folded, so that a step height between neighboring unit cells c

This paper proposes the design of small CRPA arrays for dual-band Global Positioning System (GPS) applications. The array consists of five elements and is mounted on a circular ground platform with a diameter of 15-cm. Each antenna element has a coupled feed structure and consists of a feed patch and two radiating patches for dual-band operation. An external chip coupler is utilized for a broad circular polarization (CP) bandwidth, and its measured characteristics are taken into account in our s

This paper proposes a coupled-feed structure accompanied by cavity walls for an extremely small four-element array with an aperture size of less than 0.4 λ. The feeding loop of the proposed structure is connected to two output ports of a hybrid chip coupler, and the radiating loop is coupled to the feeding loop through near electromagnetic fields confined within the substrates. This structure allows to increasing the effective dielectric constant of the antenna, which helps to miniaturize the ap

A method of array manifold calibration using one steering vector measured in a single direction is proposed. The phase information of the measured steering vector is used to derive a novel calibration matrix that is proposed to compensate for the relative phase distortion (RPD) at each antenna port. We also present a metric function defined as a standard deviation of the RPD to determine the optimum calibration angle, which provides intuition for the cause of the accuracy degradation in the dire

This study proposes the design of the periodic lossy magnetic (PLM) surface with a low profile for enhanced array characteristics. The proposed PLM surface consists of multiple rectangular grooves with equal spacing, and the grooves are filled with lossy magnetic materials to increase the surface impedance between array elements to mitigate the mutual coupling. To verify its feasibility, the authors fabricate a two‐element circularly‐polarised patch antenna array with the PLM surface inserted in