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유상길(Sang-Gil Yu),박철수(Cheol-Su Park),최순우(Swoon-Woo Choi),방재훈(Jae-Hoon Bang),안병철(Bierng-Chearl Ahn) 한국정보기술학회 2015 한국정보기술학회논문지 Vol.13 No.10
This paper proposes a Ka-band monopulse feed horn having four input rectangular waveguides. The proposed feed consists of four input waveguides, two H-moders, a E-moder and a flared horn. Two H-moders and the E-mode having waveguide discontinuous structures are designed by using the DFT function in the commercial software. The lengths of each moder and the flared horn are determined to satisfy in-phase conditions of the multi modes at the feeds aperture. Five-step waveguide transformers are designed and employed to connect the input waveguide of the feed to the WR-28 rectangular waveguide. The optimally designed monopulse feed is fabricated with 3 split blocks. The fabricated horn has a reflection coefficient of less then -10dB over 34.55-36.56GHz and a -15dB beamwidth of 100°. In the difference patterns over the azimuth and elevation planes, the null is less than -22dB at the center of the feed.
유상길(Sang-Gil Yu),최순우(Swoon-Woo Choi),김동현(Dong-Hyun Kim),김대오(Dae-Oh, Kim),안병철(Bierng-Chearl Ahn) 한국정보기술학회 2016 한국정보기술학회논문지 Vol.14 No.5
This paper presents precise measurement techniques for waveguide components at microwave band. The error parameters are presented in the network analyzer and the calibrated results are shown by using the SOLT(Short-Offset short-Load-Thru) kit when measuring waveguide components. A method is proposed to obtain the performances of the circular-rectangular waveguide transition by in order connecting 3 offset shorts. The scattering parameters of the transition are calculated from the measured reflection coefficients with 3 offset shorts. The waveguide transition has a reflection coefficient of less than -18dB and a transmission coefficient of more than –0.16dB. Next, a method utilizing a low-reflection horn at the common port of an OMT is introduced. The electric performances between the straight and side ports are measured by employing connecting a low-reflection horn at the common port of the OMT. The measurements agree well with the designed results.
왕가남(Jianan Wang),홍기표(Ki-Pyo Hong),전동하(Dong-Ha Jun),유상길(Sang-Gil Yu),안병철(Bierng-Chearl Ahn) 한국정보기술학회 2015 한국정보기술학회논문지 Vol.13 No.9
In this paper, a dual-circularly polarized feed is proposed, which operates at 54-64GHz and consists of a square waveguide, a dielectric rod radiator, a septum polarizer and waveguide bends. A stepped taper is applied to the dielectric rod for the required gain and reflection coefficient. Heights and lengths of five steps on a thin metal plate polarizer inserted in the square waveguide are optimized to obtain the desired reflection coefficient at each port, the isolation between ports, and the axial ratio. E-plane bends are connected to the output parts of the septum polarizer for connection with the WR-15 waveguide. Fabrication and measurement show that the proposed feed has a reflection coefficient of less than -10dB and a transmission coefficient of less than -9.5dB at 57-64GHz, and at 60GHz, a maximum gain of 16.8dBic, a 15-dB taper beamwidth of 60°, an axial ratio of less than 2dB within ±30° from the feed axis.