• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.5
• /
• pp.533-540
• /
• 2008

In the sum and difference pattern synthesis problem of the equi-spaced monopulse tracking linear array antennas, an efficient numerical approach to deriving the relative excitation current weights of antenna elements is presented for the desired patterns. This method is based on the optimum perturbation of null points which are inherent to the Schelkunoffs polynomial representing the pattern array factor. Accordingly, opposite to the conventional method in which the excitation weights are directly optimized, this method is advantageous in that the patterns with the desired individual sidelobe levels(SLLs) and the corresponding excitation weights are easily synthesized by the control of null points. Furthermore, it is showed that two types of difference patterns can be synthesized as imposing the different initial values of null points in the optimization process. The proposed method is numerically validated by synthesizing the patterns with the arbitrary SLLs and substituting the extracted results into the array factor equation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.4
• /
• pp.610-618
• /
• 2000

A T-shaped microstripline -fed printed slot antenna is anlayzed by using the transmission line model(TLM) in this paper. Microstrip-slotline junction is modeled by employing a transformer and the transformer turn ratio is derived empirically. The method is extended to the case of $1\times2,l\times4$array antennas. Return loss results obtained by using the transmission line model. The maximum measured results and demonstrated the usefulness of the transmission line model. The maximum bandwidths of a single antenna, $1\times2,l\times4$ array antennas are 28.5%, 47.8%, and 50.9%, respectively, for the VSWR$\leq2$. The gain of $1\times4$ array antenna is 7.97dBi and the beamwidth is about $27^{\circ}$.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.3
• /
• pp.427-437
• /
• 2008

In order to increase the coupling efficiency of the power and phase of the active phase array antenna, we have fabricated the active phased-array antenna which is coupled by the transmission line, and investigated the relationship between the length of the coupling transmission line and coupling power and phase. The following three types of driving method - (1) giving the frequency difference between the two active antenna, (2) applying the input signal to the one side of the two antennas, and changing the eigen frequency of the other side antenna, (3) appling the different phase inputs to the active antennas was investigated. The experimental results showed that the interval of the antenna elements has not affected the power and the phase of the antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.30 no.3
• /
• pp.195-201
• /
• 2019

The effectiveness of the phased array antenna in wireless power transfer systems is due to its ability to form a beam pattern towards the desired direction. To maximize the efficiency of wireless power transfer through beamforming, the transmitter must recognize the information on the optimal transmission path. To achieve this, the transmitter usually transmits pilot signals periodically and the receiver extracts the optimal beamforming weights using the pilot signals. The receiver then feeds the beamforming weights back to the transmitter. In general, the amount of feedback increases with the number of antennas, which causes feedback overhead when there is a large number of antennas. In this paper, we propose a feedback simplification scheme based on the far-field approximation method. The simulation results are provided to validate the impact of the simplified feedback on the beam pattern.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.2
• /
• pp.415-421
• /
• 2005

The radiating or receiving characteristics of array elements (i.e., antennas) are changed from those of isolated elements due to mutual coupling effects and the array performance becomes different from those originally designed by assuming isolated elements. The effects of mutual coupling on the performance of a rectangular array with triangular grid geometry of dipoles above a ground plane are discussed with respect to element pattern. The concept of element gain function is used to examine the effects of mutual coupling on the array performance in terms of sidelobe level in the uniformly spaced and space-tapered rectangular arrays with triangular grid geometry of dipoles. It was shown that the sidelobe performance improved in the space-tapered array compared to the uniformly spaced array in the presence of mutual coupling effects. Computer simulation results are presented.

• Journal of information and communication convergence engineering
• /
• v.13 no.2
• /
• pp.81-85
• /
• 2015

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.

• Journal of Positioning, Navigation, and Timing
• /
• v.12 no.1
• /
• pp.43-49
• /
• 2023

In modern wireless communication systems including beamformers or location-based services (LBS), which employ multiple antenna elements, estimating the number of signals is essential for accurately determining the quality of the communication service. Representative signal number estimation algorithms including the Akaike information criterion (AIC) and minimum description length (MDL) algorithms, which are information theoretical criterion models, determine the number of signals based on a reference value that minimizes each criterion. In general, increasing the number of elements mounted onto the array antenna enhances the performance of estimating the number of signals; however, it increases the computational complexity of the estimation algorithm. In addition, various configurations of array antennas for the increased number of antenna elements should be considered to efficiently utilize them in a limited location. In this paper, we introduce an efficient signal number estimation algorithm based on the beamspace based AIC and MDL techniques that reduce the computational complexity by reducing the dimension of a uniform circular array antenna. Since this algorithm is based on a uniform circular array antenna, it presents the advantages of a circular array antenna. The performance of the proposed signal number estimation algorithm is evaluated through computer simulation examples.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.5 no.2
• /
• pp.1-7
• /
• 1968

The characteristics of periodical discontinuities (The array of slots on the broadside of rectangular waveguide) are analysed and represented by T equivalent circuits.)

• Proceedings of the IEEK Conference
• /
• 2003.07a
• /
• pp.266-269
• /
• 2003

마이크로파 대역에서 넓은 공진 주파수 대역폭을 갖는 V 형 테이퍼드 슬롯 안테나와 1x4 선형 배열 안테나를 설계하였다. 설계주파수는 5.8 [GHz]이었고 비유 전율이 3.48 인 RO4350 기판을 사용하였으며 멀티옥타브 특성과 복사 패턴을 얻었다.

• Proceedings of the Optical Society of Korea Conference
• /
• 2004.07a
• /
• pp.8-9
• /
• 2004