• Current Optics and Photonics
• /
• v.3 no.6
• /
• pp.522-530
• /
• 2019

We present simulation methods to accurately determine the transmission efficiency and far-field patterns (FFPs) of a shallow-etched waveguide grating antenna (WGA) formed on a silicon-on-insulator wafer based on the finite-difference time-domain (FDTD) approach. The directionality and the FFP of a WGA with >1-mm in length can be obtained reliably by simulating a truncated WGA structure using a three-dimensional FDTD method and a full-scale WGA using a two-dimensional FDTD with the effective index method. The developed FDTD methods are applied to the simulation of an optical phased array (OPA) composed of a uniformly spaced WGA array, and the steering-angle dependent transmission efficiency and FFPs are obtained in OPA structures having up to 128-channel WGAs.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.22 no.4
• /
• pp.59-65
• /
• 2022

In this paper, a digital active phased array antenna is briefly introduced and beam forming method for a dual-channel side-lobe blanking applied to blank the side-lobe of the main beam is described. Next, the antenna performance was verified from results of design and antenna near-field measurement for the antenna main beam and side-lobe blanking beam. Then, a single-channel side-lobe blanking beam forming method was proposed to reduce the number of channels than the existing system operating dual-channel side-lobe blanking beam and weight distribution for each element of the side-lobe blanking antenna was designed with the proposed method. Finally, the designed single-channel side-lobe blanking beam pattern and blanking ability were verified and compared with the dual-channel side-lobe blanking beam. In addition, by comparing/verifying the conventional dual-channel and the proposed single-channel side-lobe blanking beam patterns measured through the receiving near-field test of the digital active phased array antenna and their ability to blank side-lobe of the main beam, validity of the proposed method for forming single-channel side-lobe blanking beam was confirmed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.4
• /
• pp.514-522
• /
• 2000

In this thesis, a two-dimensional active phased array antenna without phase shifter is studied for two-dimensional beam scanning. A designed two-dimensional oscillator-type active array antenna, radiation elements and the oscillator circuits were combined with via-hole and coupled by slot on the opposite ground plane. The operating characteristics are analyzed and experimentally demonstrated , The two-dimensional $4\times4$ elements were designed for the proper coupling strengths and coupling phases by adjusting the width, length and offset position of slot-lines. The fabricated active phased array antenna shows the beam shift characteristics capable of scanning from $-17^{\circ}$ to $18^{\circ}$ with respect to broadside in one dimension, from $-5^{\circ}$ to $10^{\circ}$ in two dimension. The experimental results show that it is possible to use the oscillator-type active phased array antenna as a two-dimensional planar array antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.7
• /
• pp.625-634
• /
• 2016

A full digital receiving active phased array antenna generates final receiving beams by digital beam forming of received digital signals in element-level that makes difficult to use typical near-field measurement method. Thus in this paper, a modified near-field measurement method which is suitable for full digital receiving active phased array antenna is proposed. Also the measured results of receiving beam pattern and G/T using developed L-band full digital receiving active phased array antenna are shown for the verification of proposed method.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.8
• /
• pp.1963-1970
• /
• 1998

In this paper, a two-dimensional slotline coupling structure is proposed for the planar active phased array antenna system with scanning the beam by coupled oscillators without phase shifters. The operating characteristics are analyzed and experimentally demonstrated. The proposed two-dimensional slotline coupling structure consists of $|{=}|$-type slotline in the ground plane for the coupling of E-plane and H-plane. From the simulation results of coupling strength with the variation of width, length and the number of slotlines, the optimal coupling structure is proposed and applied to $2{\times}5$ elements of planear phased array antenna. The experimental results show that the beamwidth of E-plane and H-pland are $42^{\circ}$ and $15^{\circ}$, respectivly, and the scanning range is from $-20^{\circ}$ to $15^{\circ}$ from the broadside. Therefore, it is shown the two-dimensional slotline coupling structure for oscillator-type active phased array antenna can be applied to the planar phased array antenna system.

• Journal of information and communication convergence engineering
• /
• v.18 no.4
• /
• pp.254-259
• /
• 2020

Phased-array antennas comprise a demanding antenna design methodology for commercial wireless communication systems or military radar systems. In addition to these two important applications, the phased-array antennas can be used in beamforming for wireless charging. In this study, a four-way analog beamforming front-end module (FEM) for a hybrid beamforming system is developed for 2.4 GHz operation. In a hybrid beamforming scheme, an analog beamforming FEM in which the phase and amplitude of RF signal can be adjusted between the RF chain and phased-array antenna is required. With the beamforming and beam steering capability of the phased-array antennas, wireless RF power can be transmitted with high directivity to a designated receiver for wireless charging. The four-way analog beamforming FEM has a 32 dB gain dynamic range and a phase shifting range greater than 360°. The maximum output RF power of the four-way analog beamforming FEM is 40 dBm (=10 W) when combined the four individual RF paths are combined.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.2 no.1
• /
• pp.46-54
• /
• 1991

A noble phased-array antenna of the circular form with microstrip slots was designed for steering the radiation beam and increasing the directivity and gain. The directivity and gain could be controlled, varying the number of slots and the radius of a circle, but here, the 40 .deg. beam scanning antenna system was achieved by tangentially arranging 4 mi- crostrip slots on a circumference and the analog phase shifter was used to adjust phase difference in the adjacent elements. And such a system has a microstrip configuration taking the effects of the line dispersion and discontinuities into account at 10 Ghz. The experimental results were fairly agreed with theoretical values, and this circular phased array had an improved performance over the rectangular phased array with 64-microstrip patches in a view of the number of array elements.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.10
• /
• pp.1071-1078
• /
• 2003

In this paper, the planar, compact, and broadband phased array antenna system for IMT-2000 applications has been investigated. Two methods far designing a low-cost and low-complex beam-farming network are proposed. First, a new compact and broadband phase shifter with continuously controlled phase bits is designed by using parallel coupled lines. Second, its equivalent phase delay line is suggested to be capable of replacing the complex phase shifter with a reference phase bit on a phased array antenna. For the purpose of achieving the broadband system, in addition to the broadband phase shifter, a wide-slot antenna with a ground reflector is utilized as an element antenna. Therefore, the phased array antenna system has achieved compact size, broad bandwidth, and wide steering angle, although it has low complexity and low fabrication cost. The 3${\times}$1 phased array antenna system has a compact size of 1.6 λ${\times}$ l.6 λ, which is the sufficient ground plane of the wide-slot antenna. Experimental results present that the S$\_$11/ has less than 15 dB within the band and its radiation patterns on an E-plane have the capability of steering an antenna beam from -29$^{\circ}$to +30$^{\circ}$.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.12B
• /
• pp.1752-1757
• /
• 2011

In a traditional phased array radar, closely spaced antenna elements transmit a scaled version of single waveform to maximize the signal energy. On the contrary, a multiple-input multiple-output (MIMO) radar consists of widely separated antennas and transmits an arbitrary waveform from each antenna element. These waveforms and spatial diversity enable superior capabilities compared with phased array radar. At high signal-to-noise ratio (SNR), the detection performance of the MIMO radar is better than the phased array radar due to the diversity gains. However, the phased array radar outperforms the MIMO radar at low SNR, due to the energy maximization. In this paper, we investigate the compromised scheme between the MIMO radar and the phased array radar. Employing the MIMO radar equipped with phased array elements, the compromised scheme achieves both array gain and diversity gain. Also, we compare the performance degradation when the steering direction is incorrect.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.7 no.2
• /
• pp.147-156
• /
• 1996

In this paper we proposed a beam steering equation for the planar slotted waveguide array antenna. The tilt angle measured from the rotating axis and the aperture distribution of the antenna were the most important factors for the beam steering. From the equation, we calculated the frequency and phase distribution of the aperture for any desired beam direction. And we developed a high speed control algorithm delivering the phase data to the phase shifters of a one-dimensional phased array antenna. To reduce complexity of the control circuit and the phase delivery time, we proposed the serial phase repeating method. Because of its simplicity, we expect it can be useful for a large 2- dimensional fully phased array antenna.