Earticle

본 논문에서는 저고도각 고이득 특성을 이용한 3 소자 CRPA 배열 안테나 설계를 제안하였다. 제안된 안테나는 급전패치와 방사패치로 구성되어 있으며, 급전패치에 동축케이블을 통해 급전부가 직접 연결되고 방사패치에 전자기적으로 간접급전되어 저고도각 이득특성이 개선되는 구조를 가진다. 제안된 배열안테나의 성능 측정을 전파무반사실에서 수행하였으며, 전면 방향 이득은 2.8 dBic, 축비특성은 2.7 dB, 75°의 저고도각 평균 이득이 -1.4 dBic를 나타내어 항재밍 성능을 갖는 CRPA 안테나로 적합함을 확인하였다.

In this paper, we propose a three-element CRPA array with improved low-elevation gain. The proposed antenna consists of a feed patch and a radiating patch, and the feed patch is connected by a coaxial cable. The radiating patch is electromagnetically coupled to the feed patch, which allows to improve the low-elevation gain of the antenna. To demonstrate the suitability of the proposed antenna, the antenna characteristics are measured in a full anechoic chamber. The resulting bore-sight gain is 2.8 dBic with an axial ratio of 2.7 dB, and the average gain at the low-elevation direction of 75° is -1.4 dBic. The results verify that the proposed antenna is suitable for CRPA arrays with anti-jamming capability.

Performance of wireless mobile communication can be improved by using multiple antenna techniques. For different applications different types of multiple antenna techniques are used. This paper describes the technical details of multiple antenna techniques for various types of wireless communications. A comparison of all types of multiple antenna techniques (MTA), described in this paper, is also reported.

A 94-GHz phased array antenna using a log-periodic antenna has been developed on a GaAs substrate. The developed phased array antenna comprises four log-periodic antennas, a phase shifter, and a Wilkinson power divider. This antenna was fabricated using the standard microwave monolithic integrated circuit (MMIC) process including an air bridge for unipolar circuit implementations on the same GaAs substrate. The total chip size of the fabricated phased array antenna is 4.8 mm × 4.5 mm. Measurement results showed that the fabricated phased array antenna had a very wide band performance from 80 GHz to 110 GHz with return loss characteristics better than -10 dB. In the center frequency of 94 GHz, the fabricated phased array antenna showed a return loss of -16 dB and a gain of 4.43 dBi. The developed antenna is expected to be widely applied in many applications at W-band frequency.

This paper considers a broadband multicell system with key characteristics that base-stations and relays employ beamforming via large antenna arrays, as well as in-band full duplex relay operation. The signal to interference plus noise ratio gain (which is in excess of the maximum required for such a system) could be exploited either for reducing self-interference or the backhaul and access link transmitted powers. The presented results indicate that with a moderate front-to-back-ratio scenario for the antenna array, “small” antenna arrays with 8 elements can lower the requirement of full duplex self-interference cancellation by up to 55 dB, while large antenna arrays of 1024 elements will produce 100 dB reduction. Alternatively, for the same scenario, both the backhaul and access transmitted powers could be reduced by ∼55 dB and ∼25 dB with 1024 elements.

Steering vector and covariance matrix estimation mismatch along with moving jammer/platform, can affect the performance of null-steering beamformer. In this paper, by utilizing null-widening, null-deepening and diagonal loading shrinkage in space?time adaptive processing (STAP) structure, two methods for nullifying GNSS (global navigation satellite system) jamming/interference in cruise moving platforms are introduced. The enhanced performance of the proposed methods is investigated through numerical simulations. The results indicate improvement in the number of acquired GNSS satellites, in heavy jamming (GNSS denied) scenario, by reconstructing and acquiring at least 87% of satellites.

The present paper presents an array antenna of a microstrip patch for 5G applications. Four rectangular microstrip patch elements are arranged in parallel and series to form an array antenna. Two insets are made on both sides of each patch element to achieve a wide frequency bandwidth of 23.97-31.60 GHz. To attain a high gain and wider bandwidth, the microstrip patch antenna is fed using series and corporate feeding networks. Further, three director elements on top of the top-most patch elements, and one reflector element at the open end of each patch element, are added. The addition of the Yagi elements improved the overall gain and acquired a higher radiation efficiency throughout the operating frequency bandwidth, with the array antenna achieving a maximum peak gain of 8.7 dB. The proposed antenna is built on a low-loss and low-cost substrate of FR4-eproxy. The proposed antenna design with a simple structure is suitable for Internet of Things and 5G applications.

This paper provides a space temporal interference cancellation method for ultra wide-band (UWB) communication systems based on combination of tapped delay line array antenna and orthogonal matched filter. In order to reduce the interference from the other system using overlapping frequency band, space domain signal processing such as an array antenna has been proposed. However, principal array antenna cannot be applied to impulse radio (IR) UWB because IR-UWB does not have carrier signal. In this paper, we propose a novel tapped delay line array antenna combined with orthogonal matched filter detector. From the numerical evaluation, we show that the proposed system can make null direction to face to the interference signal direction. Additionally, we show that the proposed system can reduce interference signal even if the interference signal has equivalent pulse shape and equivalent incoming direction.

Since most studies for estimating an angle-of-arrival (AOA) based on the antenna array have considered the antenna array with a single configuration, they are not proper to simultaneously estimate AOAs of multiple signals with various frequencies. In this paper, we introduce a cascade AOA estimation technique consisting of CAPON and Beamspace Multiple Signal Classification (MUSIC), based on a Combined Array Antenna (CAA) with Uniform Rectangular Frame Array (URFA) and Uniform Circular Array (UCA), for enhancing the above problem. In addition, we provide the computational complexity analysis for showing the low computational complexity of this technique comparing to the conventional technique.

This paper newly proposes a direct antenna array control approach to reduce channel spatial correlation for multiuser spatial multiplexing. Conventional rectangular arrays can form three dimensional beams and have superior signal separation performance compared to linear arrays. However, when the arrival angles of some signals are close, the signal separation (interference cancellation) performance deteriorates since the projection points onto horizontal/vertical axes of several antenna elements overlap and spatial resolution along each axis is degenerated. The key proposal is to improve signal separation performance by mechanically changing the positional relationship of antenna elements. The proposed scheme can achieve better Bit Error Rate (BER) performance by searching the optimal antenna rotation angle.

Adaptive smart antenna arrays are used for cellular communication. This paper presents a comparative study of beamforming techniques for adaptive smart antenna using hybrid algorithms like Simple Matrix Inversion with Recursive Least Square (SMI-RLS) and Least Mean Square with Recursive Least Square (LMS-RLS) algorithm. The results are compared on the basis of null depth and error plot for different signal –to-noise (SNR) values, ranging from high to low values of SNR for heavily faded case..

위성방송수신 및 위성 양방향 인터넷, VSAT 등의 위성통신서비스를 차량 이동 시에도 이용할 수 있기 위해서는 차량에 탑재하기 용이하도록 소형이며 높이가 낮은 안테나 구조가 요구된다. 또한 중위도 지역에서 평면 안테나 상태로 45도 틸트 특성을 갖고, Ku 밴드의 위성통신용으로 충분한 고이득을 얻기 위해, 빔폭이 좁고 사이드로브가 적으며 저손실 구조의 배열안테나 개발이 필요하다. 본 논문에서는 이러한 성능을 만족시키기 위해, 진행파형 누설파 모드를 기초로 한 수직 편파로 동작하는 도파관 종방향 슬롯 배열안테나를 제안하였다. 16개 누설파 소자의 배열안테나 이득은 30 dBi 이었으며, 빔폭은 4.9도, 사이드로브 레벨은 -20 dB 이하, 중심주파수에서 빔틸트 각도는 45도를 얻었다. 급전선로는 도파관의 병렬급전 방식으로 설계하여 광대역, 저손실 특성을 얻을 수 있었다.

Small size and low profile antenna for mobile vehicular-top-mounted is needed in satellite communication services such as DBS, Satellite Internet and VSAT. In middle latitudes, the development of an array antenna which has the conformal, low profile and 45 degree beam tilted configuration, and has the high gain with sharp beamwidth, low sidelobe and low loss is required for Ku-band satellite communication. In this paper, in order to meet with these performances, an array antenna consisting of the vertical polarized waveguide longitudinal slots based on the leaky-wave mode of traveling wave antenna is proposed. An array antenna consisting of 16 leaky-wave elements is showing 30 dBi of gain, 4.9 degree of beamwidth, below than -20 dB of sidelobe level, 45 degree of beam tilt angle in center frequency. Feed network designed by waveguide cooperated feed shows good performance of wideband and low loss.

The structure of MMSE receiver front-ended by CMA(Constant Modulus Array) array working in CDMA forward link which is applicable to LEO spread spectrum satellite communication system is proposed. By using the despreaded pilot signal of forward link as a reference signal, the CMA array can capture multi-path signals securely even in severely faded LEO satellite channel. The remaining MAI (Multiple Access Interference) is cancelled by the cascaded MMSE receiver. Besides theoretical development, through relevant computer simulation, it is proved that the proposed system shows much better BER performance than any other possible candidate systems. As a spatio-temporal receiver mounted on a mobile vehicle, the proposed system also reduces implemental cost and complexity by adopting the simplest algorithm for its spatial and temporal domain processing.

본 논문은 고정위성업무(FSS; Fixed-Satellite Service) 및 방송위성업무(BSS; Broadcasting-Satellite Service)의 다운링크 대역을 통합하는 Ku 대역의 위성통신용 광대역 혼합 패치 배열 안테나의 설계에 관한 것으로써, 제안한 안테나는 FR4 기판 상에 사각 패치를 6 x 2 형태로 배열하여 구현되었다. FSS 다운링크 대역(10.7~10.95 GHz, 11.2~11.45 GHz) 및 BSS 다운링크 대역(11.7~12.5 GHz, 12.2~12.75 GHz, 11.7~12.2 GHz)을 모두 포함하는 광대역(10.7~12.75 GHz) 안테나를 설계하기 위해 11.5 GHz 및 12.5 GHz에서 동작하는 사각 패치를 각각 교대로 배열하였고 이를 통해 중심주파수의 30.8%에 해당하는 광대역을 확보하였다. 안테나의 성능을 확인하기 위해 제안한 안테나를 제작 및 측정하였고 모의시험 결과와 유사함을 확인하였으며 따라서 제안된 안테나는 FSS 및 BSS 다운링크를 위한 안테나로 적용이 가능하다.

This paper proposes a design of a wideband array antenna involving the downlink bands of fixed satellite service (FSS) and broadcasting satellite service (BSS) by applying two mixed patch sets. The proposed antenna is implemented on FR4 substrate by arranging rectangular patches in 6 by 2. To design a wideband antenna (10.7~12.75 GHz) covering both FSS downlink bands (10.7~10.95 GHz, 11.2~11.45 GHz) and BSS downlink bands (11.7~12.5 GHz, 12.2~12.75 GHz, 11.7~12.2 GHz), rectangular patches working at 11.5 GHz and 12.5 GHz are arranged alternately, and thus the proposed antenna can obtain a wide bandwidth equivalent to 30.8% of the center frequency. The proposed antenna was fabricated and measured, and the results are well matched with the simulated ones. From the performances, the proposed antenna can be applied to the receiving antenna for FSS and BSS downlinks.

종래 유도탄의 경우 대부분 유도탄의 전방부에 GPS (Global Positioning System) 안테나가 장착되는 경우가 많아 종말 유도단계에서 수직 낙하하는 유도탄의 경우 GPS 안테나가 전방부에 위치하면 동체에 의한 위성 신호 가림 현상이 생겨 GPS 성능이 떨어진다. 본 논문에서는 위성 신호에 대한 가시영역을 최대로 확보하기 위해 GPS 안테나를 유도탄의 후방 부에 기울임을 주어 배치하였으며 배열안테나의 패치를 기울여 설계하는 것을 제안하였다. 제안된 안테나 배치 형상에 대하여 GPS 신호의 신호 수신 범위를 분석하기 위해 LOS (Line Of Sight) 관점에서 가시영역을 분석하였고 실제 무반향 챔버에서 수신 신호 세기 측정을 통해 위성 신호의 유효 수신영역을 분석하였다. 또한 야외시험과 비행시험을 통해서 위성 신호의 음영지역이 줄어드는 것을 확인함으로써 GPS 안테나가 유도탄의 후방에 배치되었을 때 얻을 수 있는 장점을 확인하였다.

In this paper we investigate the advantages when the GPS Antenna is installed on the rear missile body. In conventional design the GPS antenna locates on the front part of missile. However it causes degraded GPS positioning performance since the missile body blocks the GPS signals. This paper proposes the GPS array antenna design which locates on the rear part of missile body and has the tilted antenna patches to achieve the maximum area of receiving GPS signals. We simulate LOS region of receiving signals and conducted anechoic chamber test to define the effective signal receiving region. And we conduct field test and flight test to check out the enhancement of signal receiving area.

본 논문에서는 패치배열안테나에 혼 형상의 반사기를 적용하여 넓은 빔 폭을 형성하는 안테나를 연구하였다. 넓은 빔 폭을 구현하기 위해 정사각형 마이크로스트립 기판 상의 4개 방면에 3개의 패치들을 각각 배열하였고, 배열안테나 후방에 혼(Horn) 형상의 반사기를 각각 적용하였다. 이 구조를 통해 패치로부터 형성 된 수직 빔 패턴이 사선 방향으로 변환되었고 결과적으로 네개의 섹터에서 형성된 각각의 빔 폭이 더해져서 반구형에 가까운 넓은 빔 폭을 만들 수 있었다. 제안된 안테나는 UAV(unmanned aerial vehicle)에 적용하기 위해 연구되었고 모의시험결과, 4.5 dBi 빔 폭이 146.8°임을 확인하였다.

In this paper, we studied an antenna that forms a wide beam width by applying a horn-shaped reflector to a patch array antenna. To implement a wide beam width, three patches were arranged in each of the four directions on a square microstrip substrate, and a horn-shaped reflector was applied to the rear of the array antenna. Through this structure, the vertical beam pattern formed from the patch was converted to a diagonal direction, and as a result, the beam widths formed in each of the four sectors were added to create a wide beam width close to a hemisphere. The proposed antenna was studied for application to UAV(unmanned aerial vehicle), and the simulation test results confirmed that the 4.5 dBi beam width was 146.8°.