In this paper, we propose a deployable broadband mesh reflector antenna for use in signals intelligence (SIGINT) satellite systems, considering performance degradation due to shape deformation. To maximize gain by increasing the diameter of the reflector while reducing the weight of the antenna, the reflector of the antenna is designed using lightweight silver-coated Teflon mesh. The mesh reflectors are typically expanded by tension to maintain their parabolic structure; thus, shape deformation cannot be avoided. This shape deformation results in shape differences between the surface of the mesh reflector and the ideal parabolic reflector, thus resulting in the degradation of the performance of the mesh reflector antenna. To observe this degradation, we analyze antenna performance according to the number of arms, the number of joints, the feed distance, and the distance from the reflector center to each joint. The performance of the mesh reflector antenna is examined using an effective lossy conducting surface (ELCS) that has the same reflectivity as the silver-coated Teflon mesh to reduce simulation time and computing resources. The designed silver-coated Teflon mesh reflector and the double-ridged feed antenna are fabricated, and the bore-sight gain is measured using the three-antenna method. The measured bore-sight gain of the proposed antenna is 31.6 dBi at 10 GHz, and the measured and simulated results show an average difference of 3.28 dB from 2 GHz to 18 GHz. The proposed deployable mesh reflector antenna can be used in a variety of applications where small stowed volume is required for mobility, such as mobile high-gain antennas as well as satellite antenna systems. Through this study, we demonstrate that shape deformation of the mesh reflector surface significantly affects the performance of reflector antennas.

This paper proposes a novel wideband leaf-shaped printed dipole antenna sensor that uses a parasitic element to improve the impedance matching bandwidth characteristics for high-power jamming applications. The proposed antenna sensor consists of leaf-shaped dipole radiators, matching posts, rectangular slots, and a parasitic loop element. The leaf-shaped dipole radiators are designed with exponential curves to obtain a high directive pattern and are printed on a TLY-5 substrate for high-power durability. The matching posts, rectangular slots, and a parasitic loop element are used to enhance the impedance matching characteristics. The proposed antenna sensor has a measured fractional bandwidth of 66.7% at a center frequency of 4.5 GHz. To confirm the array antenna sensor characteristics, such as its active reflection coefficients (ARCs) and beam steering gains, the proposed single antenna sensor is extended to an 11 × 1 uniform linear array. The average values of the simulated and measured ARCs from 4.5 to 6 GHz are −13.4 dB and −14.7 dB. In addition, the measured bore-sight array gains of the co-polarization are 13.4 dBi and 13.7 dBi at 4 GHz and 5 GHz, while those of the cross-polarizations are −4.9 dBi and −3.4 dBi, respectively. When the beam is steered at a steering angle, θ₀, of 15°, the maximum measured array gains of the co-polarization are 12.2 dBi and 10.3 dBi at 4 GHz and 5 GHz, respectively.

In this paper, we propose an all-metal Vivaldi array antenna with dual-slant polarization for high-power jammer systems. The single Vivaldi element of the proposed array consists of radiating flares and an inner cavity to achieve high directivity and wide-frequency band impedance-matching characteristics. We expanded the proposed Vivaldi element to a 4 × 4 array antenna with dual-slant polarization considering the occurrence of grating lobes. The fabricated array antenna produced measured active voltage standing wave ratios below 2.74:1 (Port 1) and 2.85:1 (Port 6) in the frequency range of 2.5–5.5 GHz for all steering angles. In addition, the measured array gain is above 9.5 dBi in the frequency range from 2 GHz to 6 GHz. These results confirm that the proposed array antenna consisting of metallic components for high durability is suitable for application to high-power jammers.

한국전자파학회논문지 (The Journal of Korean Institute of Electromagnetic Engineering and Science)

This paper analyzes performance degradation caused by mechanical errors in rib-type deployable mesh reflectors to propose error tolerance levels that can be used as a reference when designing antennas composed of these reflectors. In rib-type deployable mesh reflectors, five types of errors may occur: joint stop angle error, feeder alignment error, feeder pointing error, defective surface error, and wrinkled surface error. In this study, antenna performance degradation stemming from these mechanical errors are analyzed, and error tolerances corresponding to a reduction in the boresight gain by 1 dB (20.6%), 2 dB (36.9%), and 3 dB (50%) are suggested. These boresight gain reduction levels are widely adopted as intuitive indicators of antenna performance degradation. In addition, the corresponding variations in half-power beamwidth, sidelobe level, and main lobe direction are calculated for each error case. The error tolerances at which a performance degradation of 1 dB occurs for each error type are as follows: 0.32° at 10 GHz for joint stop angle error, 9.5% at 3 GHz for defective surface error, 0.0071 m at 10 GHz for wrinkled surface error, 0.016 m at 10 GHz for feeder alignment error, and 23.6° at 3 GHz for feeder pointing error. These results reveal that the most sensitive and critical error is the joint stop angle error, which must be significantly minimized when designing and fabricating rib-type deployable mesh reflector antennas.

전자기 스펙트럼 작전 환경에서는 통신 시스템의 성능 확보를 위해 레이더 간섭을 보상할 수 있는 기술이 필요하다. 본 논문에서는 레이더 펄스 신호가 존재할 때 통신 시스템의 수신기에서 간섭 신호의 영향을 학습하여 오류 발생을 감소시킬 수 있는 기계 학습 기반의 복조 구조를 제안한다. 제안하는 복조기는 심층 신경망을 이용하여 구성되며, 은닉층의 개수와 노드 개수에 따른 심볼 오류율 성능을 분석하여 저복잡도의 복조 신경망 구성 방안을 제시한다. 컴퓨터 시뮬레이션 결과를 통해 간섭 대 신호비가 0.5보다 큰 상황에서 신호 대잡음비 25 dB 기준으로 기존의 최대 우도 복조 방식은 약 10%의 심볼 오류율을 나타내었으나, 제안하는 기계학습 기반 복조는 0.01%의 심볼 오류율을 나타내는 것을 확인하였다.