• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.7
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• pp.1282-1290
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• 2000

The LHCP circularly polarized antenna operating at the satellite broadcast receiving band is developed by employing the sequential-rotation technique in which each truncated-corner patch square element is arranged in the triangular lattice type. Antenna designed with sequentially rotated technique of triangular lattice type has the effect of improved axial-ratio bandwidth, cross-polarization etc., and the degradation of radiation pattern can be reduced significantly by minimizing the radiation loss of feeding line structure. Characteristics of antenna designed is satisfied with specifications of array antenna for DBS that is -27 dB of side lobe level and -20 dB of cross-polarized level at $\Phi$=45$^{\circ}$ plane.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.7
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• pp.769-777
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• 2010

In this paper, a switchable circularly polarized microstrip patch antenna using PIN diodes and corner slots on ground plane is proposed at 2.4 GHz. The proposed antenna has a square microstrip patch and ground plane that consists of two pair of slots and PIN diodes. The electrical lengths of the slots are adjusted by using the switching characteristic of the PIN diode, so the polarization of the proposed antenna can be switchable between linear, left-handed(LH) and right-handed(RH). By separating the ground plane for the DC bias, the size reduction effect is also obtained. When the proposed antenna is operated as linear polarization, the return loss and impedance bandwidth are 15 dB, 59 MHz, and when operated as LH and RH polarization, the minimum axial ratio and 3-dB axial ratio bandwidth are 1.17 dB, 1.67 dB, 28 MHz, and 32 MHz, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.156-163
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• 2014

In this paper, a compact circularly polarized metamaterial patch antenna using cross aperture-coupled feed is proposed. The CP antenna utilizes the -1 mode that is induced by the composit right-left handed(CRLH) transmission line. Since the -1 mode has the same properties with the $TM_{010}$ mode of the conventional patch antenna, the circular polarization(CP) can be realized. If two orthogonal modes are excited with $90^{\circ}$ phase difference, the CP property can be obtained. In order to obtain two orthogonal modes and $90^{\circ}$ phase difference, 4 mushroom structures having the shape of square are employed. The width and length of the cross aperture are optimized through the design algorithm. The fabricated antenna is based on RT/duroid5880 substrate and the total area of the 4 mushroom is $0.25{\lambda}_0{\times}0.25{\lambda}_0$. The center frequency of the LHCP(Left-Handed Circular Polarization) antenna is measured as 1.622 GHz and circular polarization bandwidth(3 dB) is measured as 3 MHz. The center frequency of the RHCP(Right-Handed Circular Polarization) antenna is measured as 1.609 GHz and circular polarization bandwidth (3 dB) is measured as 3 MHz, respectively. The measured radiation efficiency of LHCP antenna is 61.1 % and the measured radiation efficiency of RHCP antenna is 54.5 %.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.1022-1032
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• 1999

The radiation characteristics of a microstrip circularly-polarized aperture-patch $8\times8$ array antenna are investigated at X-band. The radiator consists of a truncated square aperture on the ground plane with an inclined rectangular patch inside, and it is coupled by a microstrip line on the opposite side of the ground. The element spacing of the array was chosen as $0.8\lambda_0$so as to minimize the mutual coupling and maximize the gain. A corporate feed network was employed to distribute the power to each element through four Wilkinson and two T-junction dividers. Measurement results for the $8\times8$ array at 10 GHz showed a directivity of 26.3 dBi, a gain of 22.2 dBi, an axial ratio of 2.97 dB, and a side lobe level of -12.7dB. It was observed that when the array size increases, the directivity increases while the efficiency decreases.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.6
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• pp.525-532
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• 2015

In this paper, we propose an equivalent model of array antennas that use open-ended waveguides for effective EM simulation. We first investigate an individual element that consists of an open-ended waveguide and square ground plane. The waveguide length, aperture size, and ground size of the individual element are adjusted to give a similar radiation pattern to that of the individual element of the original antenna. We then apply the designed equivalent model to two different types of array antennas, such as a microstrip patch array and a waveguide array antenna. Comparison of the simulation results using the equivalent model with the results obtained with the original antenna reveals a difference in gain of less than 0.2 dB and a difference in half power beam width(HPBW) of less than $1^{\circ}$. The designed equivalent model is then mounted on a simple aircraft, and the simulation results are again compared to results from the original antenna. We find a 60 % reduction in simulation resources and time when compared with the original antenna model.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.164-171
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• 2014

Transmit(Tx)/Receive(Rx) dual band operation microstrip array for X-band satellite communications are designed, fabricated, and measured in this paper. The microstrip array antenna has Right Handed Circular Polarization(RHCP) for Tx band and Left Hand Circular Polarization(LHCP) for Rx band. Two stacked patches are used for wideband characteristics and corner-truncated square patches are adopted for a circular polarization. To enhance bandwidth characteristics of a circular polarization, $2{\times}2$ sequential rotation array are applied. From the measured result, $8{\times}12$ microstrip array antennas have a good agreement with those of the simulation. Therefore the array antennas are applicable to military satellite communication antennas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1316-1324
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• 2009

In this paper, cross-aperture coupled microstrip circular polarization antenna is proposed for 5.8 GHz WLAN(Wireless Local Area Network). A single antenna consists of square patch and slots are located in series feed line with $\lambda_g$/4 phase different which make current direction maximum and minimum repeatedly to generate RHCP(Right Handed Circularly Polarization). We are proposed new structure that removed the section which intersected at a right angle and were composed to four separated slots. The proposed cross slots reduce back lobe of radiation pattern and improve antenna gain. Impedance bandwidth of the manufactured $2\times2$ array antenna is from 5.67 to 5.95 GHz and the maximum radiation gain is 10.59 dBi.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1367-1374
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• 2008

A new high-gain Fabry-$P{\acute{e}}rot$ cavity antenna for wireless broadband internet(Wibro) base station antennas, which is covered with metamaterial superstrate presenting simultaneous negative values of permittivity and permeability, is proposed. To facilitate the fabrication process using the printed circuit board(PCB) technology of today, a new planar-type metamaterial superstrate is designed, which shows negative and low positive values of a refractive index near the Wibro service frequency band. And the principle of antenna gain enhancement is analyzed from the two different view points of effectively low refractive index and of the Fabry-$P{\acute{e}}rot$ resonance condition. Single square patch antenna is used as a feeder. The separation distance is determined by considering the reflection phases of the metamaterial superstrate and the substrate satisfying Fabry-$P{\acute{e}}rot$ resonance condition, respectively. Comparison between the prediction and the measurement shows good agreement, which verifies the validity of our design approach.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.5
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• pp.747-756
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• 1999

In this paper, we analyzed microwave-DC conversion efficiency for the dual-polarization rectenna and antenna position changing. And then we analyzed and applied Square-Loop FSS structure for reducing the diode harmonic components as a rectifying circuit. The results of microwave-DC conversion efficiency for the each of designed dual-polarization rectenna has 69.1% with $360\Omega$ (dipole type) and 75.4% with $340\Omega$ (patch type) optimum load resistor. When the each of dual-polarization rectenna has a optimal load resistor, it's conversion efficiency shows of $\pm$20% in dipole type and $\pm$5% in patch type at $0~180^{\circ}$position. When applied Square-Loop FSS structure for Rectenna, Insertion loss was under 1 dB as the passband and over 20 dB as the stopband. The microwave -DC conversion efficiency was represented good properties of $\pm$2% variation.

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.226-229
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• 2007

본 논문에서는 사각형 링을 갖는 UHF대 RFID 리더기용 소형 원편파 패치 안테나를 설계 제작하였다. 정사각형의 패치 안테나를 설계하고, 원편파를 위한 Truncated 패치 안테나를 설계한 후, 소형화를 위해 사각형의 링을 갖는 Truncated 패치 안테나를 설계하였다. 주파수 대역은 UHF대역인 902928MHz이며, 설계를 위하여 HFSS simulation올 사용하였다. 비유전율 4.3, 두께 1.6mm, 손실탄젠트 =0.019의 epoxy 기판을 사용하여 실현하였다. VSWR, 방사이득, RHCP, LHCP의 큰 변화없이 사각형의 링을 이용하여 기본 Truncated 안테나보다 6.37% 소형화시켰다.