• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.2
• /
• pp.111-118
• /
• 2003

Notch Antenna is a travelling wave type antenna and can provide multioctave operation in phased arrays that scan over wide angle. In this paper, we designed a wideband E-plane phased array antenna using E-plane waveguide simulator which has a bandwidth of 3 : 1 and a scan volume of $\pm$45$^{\circ}$ in E-plane. We compared impedance of single antenna and infinite array antenna using equivalent circuit modeling. We analyzed full structure of 1$\times$9 phased array antenna and we evaluated active reflection coefficient with variation of beam scan angle through mutual coupling coefficient acquired from simulation and investigated the variation of antenna gain with variation of active element pattern as beam scan angle is varied.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.5
• /
• pp.981-989
• /
• 1997

In this paper, the 5-element active phased array antennas coupled through slotline between elements are designed and fabricated. A recent studies on the active phased array antennas using the transmission line coupling which can be designed to provide strong coupling and the appropriate coupling phase. But this sturucture has limitation of expanding in two dimensions for planar active phased array antennas and distortion of the radiation pattern caused by coupling network. Thus our work proposes the slotline coupling structure asthe broadband coupling network for the active phased array antenna. In experiment, 5-elements active phased array antenas have steering range from -30.deg. to 20.deg. off broadside as the free-running frequencies of end elements are controlled. The overall results show that the proposed slotline coupling structure is suited for the coupling network in the actie phased array antenna system. And the proposed coupling structire solves the expansion problem and eliminates the distortion of the radiation pattern caused by the spurious radiation of the transmission line coupling network. Thus thiscan be expanded to two dimensional coupling network for the planar active phased array antenna system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.2
• /
• pp.217-222
• /
• 2014

This paper discusses about the beam pattern distortion caused by the failures of some antenna modules in the active array antenna and analyses the possibility of improvement through applying the beam pattern compensation method previously studied. The beam pattern distortion which is mostly represented as an increase of the sidelobe level, can be suppressed through re-synthesizing each module's magnitude and phase. This method was applied to the prototype of active array antenna system, and the results of antenna pattern distortion and compensation were analyzed and measured in the Near Field Chamber. Array failures are generally divided into random TR module failures and TRU(TR Unit: combination of TR modules, Beam Computation module, Power supply module) failures. The results of beam pattern compensation were analyzed in each failure and compared to the results of the simulation. The beam pattern compensation results applied to the real active antenna array system showed the similar to the simulation results. Consequently, it was verified the beam pattern could be compensated with the magnitude and phase adjustment of other normal antenna modules.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.64 no.3
• /
• pp.438-444
• /
• 2015

A new approach to the active phased arrays for the second harmonic generation is presented. Phase variation between the second harmonic oscillators by the mutual synchronization is analyzed theoretically. In this coupling, the active antenna consists of the FET oscillator which plays two roles in fundamental oscillation and frequency multiplying, and the patch antenna resonated at the second harmonic frequency. The radiated second harmonic wave was scanned by varying the free-running oscillation frequencies of the active antennas. In the experiment using the 2-elements array and the 4-elements array, the radiated beam of the second harmonic wave was scanned more widely compared with the case of the fundamental wave radiation.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.4C no.6
• /
• pp.306-309
• /
• 2004

This paper presents a new active antenna consisting of a microstrip patch for the passive radiator, a mixer for frequency conversion, a voltage controlled oscillator (VCO) and a phase detector for phase control. The microwave signal frequency has been converted into intermediate frequency (IF) on the antenna elements by the mixer. The active antenna consists of two ports, the IF port has a transmitted IF signal via power combined to the baseband and the dc control port is under the control of the phase-detector. The input voltage of the VCO is controlled by the phase detector. The scan range of the array is determined by the phase detector and the VCO and is obtained between 30$^{\circ}$ and - 30$^{\circ}$

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.12
• /
• pp.1155-1164
• /
• 2011

In this paper, we proposed the transmit beam measurement method of active phased array antenna, which is installed in Korea's first developed naval medium range radar, using near-field measurement facility. The pulse-mode high power characteristics of active phased array antenna's trasmit-beam make it difficult to measure with general near-field measurement facilities where low power continuous RF signals are used. Thus, in this paper, the measurement method of active phased array antenna's transmit beam in conjunction with the near-field measurement facility, which is suitable for the high-power transmit beam measurement, and PNA-X network analyzer(Agilent Technologies), which can support pulse-mode measurement, was proposed and measured by near-field measurement techniques. And the EIRP(Effective Isotropic Radiated Power), the transmit characteristic of active phased array antenna, was measured by the near field measurement techniques and compared to numerical estimation which was nearly equal with small difference of 0.1 dB.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.1
• /
• pp.6-16
• /
• 2009

For the application to the direction finding(DF) antenna for V/UHF bands, circular active array composed of 9 dipole element has been investigate. For miniaturization of the overall size array, the element has been chosen to be of the top-hat dipole type. For the broadband operation over 20-1300MHz, some number of pin diodes have been inserted in each arms of each dipole element. By employing this type of each element dipole, the effective dipole length can be increased or decreased according as the inserted pin diodes is on or off. The active array antenna has been design to be directly connected to the balanced push full amplifier such that the amplifier may play a role as a balloon and may improve the sensitivity as a receiver as well. The active array antenna has been designed and fabricated. Some experimental results have been presented in comparison with simulated results.

• Journal of electromagnetic engineering and science
• /
• v.18 no.3
• /
• pp.175-181
• /
• 2018

The array patterns of a patch array antenna were calculated using an active element pattern (AEP) method that considers ground edge effects. The classical equivalent radiation model of the patch antenna, which is characterized by two radiating slots, was adopted, and the AEPs that include mutual coupling were precisely calculated using full-wave simulated S-parameters. To improve the accuracy of the calculation, the edge diffraction of a ground plane was incorporated into AEP using the uniform geometrical theory of diffraction. The array patterns were then calculated on the basis of the computed AEPs. The array patterns obtained through the conventional AEP approach and the AEP method that takes ground edge effects into account were compared with the findings derived through full-wave simulations conducted using a High Frequency Structure Simulator (HFSS) and FEKO software. Results showed that the array patterns calculated using the proposed AEP method are more accurate than those derived using the conventional AEP technique, especially under a small number of array elements or under increased steering angles.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.12
• /
• pp.1031-1043
• /
• 2015

This paper describes the pattern synthesis method of two kinds of conformal array antenna using the Enhanced Adaptive Genetic Algorithm (EAGA). One is the $1{\times}16$ conformal array antenna on a curved cylindrical metallic surface with quadratic function, and the other is the 18-element conformal arrary antenna on a metallic surface obtained by the rotation of a quadratic function curve around the axis. The active element pattern is utilized in the pattern synthesis. Especially for the case of the rotated-type conformal array antenna the transformed active element pattern obtained from the Euler's angle rotation of the active element pattern of the planar concentric array is utilized, which reduces the synthesis time a lot. To verify the validity of the proposed synthesis method the MATLAB results are compared with the MWS results. Furthermore, for the case of $1{\times}16$ conformal array antenna the measured results are compared with the MATLAB synthesized results.

• 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.