• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.8
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• pp.730-739
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• 2015

In this paper, a wideband circular polarizer operating in the frequency range of 6~18 GHz is designed and fabricated using a multilayer structure with meanderlines. A T matrix expression for the unit structure, which consists of meanderline, dielectric substrate and spacer, was derived using the boundary value solution. A proposed meanderline structure was modeled as an array of unit meanderline cell in order to apply the waveguide model with PEC and PMC boundary conditions. The calculation procedures to obtain an equivalent susceptance of the unit meanderline cell using HFSS was also suggested. Using a hybrid method, which combines the T matrix with the HFSS results, and cut-and-try method, a wideband circular polarizer with low insertion loss and good AR performance was designed. The fabricated polarizer has the return loss less than -10 dB within 92 % bandwidth, the average insertion loss less than -0.24 dB, and the average AR below 2.6 dB for full 3:1 bandwidth.

• Journal of Advanced Navigation Technology
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• v.28 no.2
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• pp.232-237
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• 2024

In this paper, a broadband double dipole quasi-Yagi antenna using a 4×2 meander line array structure for maintaining 8 dBi gain was studied. The 4×2 meanderline array structure consists of a unit cell in the shape of a meanderline conductor, and it was placed above the second dipole antenna of the double dipole quasi-Yagi antenna. A double dipole quasi-Yagi antenna with generally used multiple strip directors was designed on an FR4 substrate with the same size, and the input reflection coefficient and gain characteristics were compared. Comparison results showed that the impedance frequency bandwidth increased by 6.3% compared to when using the multiple strip directors, the frequency bandwidth with a gain of 8 dBi or more increased by 10.1%, and average gain also slightly increased. The frequency band of the fabricated antenna for a voltage standing wave ratio less than 2 was 1.548-2.846 GHz(59.1%), and gain was measured to be more than 8 dBi in the 1.6-2.8 GHz band.

• Journal of Advanced Navigation Technology
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• v.27 no.4
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• pp.447-452
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• 2023

In this paper, gain enhancement of a double dipole quasi-Yagi antenna using a meanderline array structure was studied. A 4×1 meanderline array structure consisting of a meanderline conductor- shaped unit cell is located above the second dipole of the double dipole quasi-Yagi antenna. It was designed to have gain over 7 dBi in the frequency range between 1.70 and 2.70 GHz in order to compare the performance with the case using a conventional strip director. As a result of comparison, the average gain of the double dipole quasi-yagi antenna with the proposed meander line array structure was larger compared to the case with the conventional strip director. A double dipole quasi-Yagi antenna using the proposed meanderline array structure was fabricated on an FR4 substrate and its characteristics were compared with the simulation results. Experiment results show that the frequency band for a VSWR less than 2 was 1.55-2.82 GHz, and the frequency band for gain over 7 dBi was measured to be 1.54-2.83 GHz. The frequency bandwidth with gain over 7 dBi increased, and average gain also slightly increased, compared to the conventional case using a strip director.