• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.1
• /
• pp.110-118
• /
• 2004

In this paper, a method is presented for the design of an orthomode transducer(OMT) operating at 21/31GHz frequency bands. A square waveguide is used in the common port while the WR-34 standard rectangular waveguide is used in the straight port. The straight port is connected to the common port via a multi-stage quarter-wave impedance transformer. The side port is coupled to the common port through a slot formed along the center line of the common square waveguide. An impedance transformer is employed to match the impedance of the coupling slot with that of the WR-51 waveguide at the output of the side port. Dimensions of the OMT are iteratively optimized employing the theory of waveguide. The validity of the proposed method is verified by fabricating and testing the designed orthomode transducer.

• Journal of Astronomy and Space Sciences
• /
• v.30 no.4
• /
• pp.345-353
• /
• 2013

A W-band Orthomode Transducer (OMT) has been developed for Korean VLBI Network (KVN) polarization observation. The OMT design was based on E-plane split-block technique using septum structure. 3-dimensional electromagnetic simulation was fully employed to optimize the performance of the OMT. Measurements of the fabricated OMT show that the return losses for the vertically and horizontally polarized modes are better than -20 dB across 80 ~ 108 GHz and the insertion losses for the both modes are less than 0.47 dB. The cross-polarization level of the OMT is less than -30 dB. The bandwidth of the developed OMT is estimated as around 30%.

• Proceedings of the IEEK Conference
• /
• 2002.06a
• /
• pp.363-366
• /
• 2002

In this paper, we present a Ku-band OMT(orthomode transducer) structure employing a simple waveguide transition withou a septum. Various aspects of the OMT design are discussed. The design is carried out using a commercial software HFSSe The designed OMT shows good characteristics over 12.5114.25 CHz frequency bands.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.6B
• /
• pp.1149-1155
• /
• 1999

This paper presents a narrow-band orthomode transducer(OMT) based on waveguide to waveguide transitions which can separate two linearly polarized orthogonal modes. This operates in the range 120Hz-13GHz frequency band. It consists of two parts, main arm and side arm. Stepped transformers are designed and an inductive post is inserted to improve the characteristics of the transmission loss and isolation. This paper also presents results from fabricated OMT These results show that the transmission loss is less than 1dB and the isolation between the ports for the OMT is above 20dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.12 s.91
• /
• pp.1123-1130
• /
• 2004

In this paper, a technique is presented f3r the design of a structurally simple narrow-band orthomode transducer (OMT) operating at 12/14 GHz frequency bands. The proposed OMT has such a structure that a horizontally polarized wave incident on the circular waveguide of the common port is directed to the rectangular waveguide of the straight port, while the vertically polarized wave is directed to the rectangular waveguide of the side port. Firstly methods are developed f3r designing individual parts of the OMT based on the waveguide theory and the theory of impedance matching. Secondly based on developed methods the whole OMT structure is designed using a commercial electromagnetic field analysis software. The validity of the proposed design technique is confirmed by fabricating and testing the designed OMT.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.1
• /
• pp.53-59
• /
• 2002

In this paper, we present design results for an orthomode transducer(OMT) to be used in multi-band antenna feeds. The OMT is realized in the form of a tapered square waveguide, where 18-20 GHz ports are placed in the taper region normal to the waveguide axis, while 30-45 GHz ports are placed in line with the waveguide axis. The reflection coefficient of each port is designed to be less than 20 dB, while the isolation between ports are greater than 15 dB. Thin septa are placed in side ports to reduce the effect of side ports on the return loss of the in-line port. The commercial software HFSS？ is used to design the whole structure.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2001.11a
• /
• pp.184-188
• /
• 2001

본 논문에서는 다중대역 피드를 위한 직교모드 변환기를 설계하였다. 직교모드 변환기의 전체적인 모양은 사각 테이퍼진 형태이고, 18-20 GHz 에서 우원 편파와 좌원편파를 발생시키기 위해 테이퍼 부분에 2개의 측면포트를 두고, 직선포트는 30-45 GHz의 광대역에서 -20dB 이하의 반사계수를 가지도록 설계하였다. 직선포트에서의 반사계수 특성을 향상시키기 위해서 측면포트에 얇은 격막을 삽입하였다. 전체적인 설계에 상용소프트웨어인 HFSS$^{R}$를 사용하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.7
• /
• pp.711-719
• /
• 2011

A study of miniaturization of an L-band orthomode transducer(OMT) for field experiments of radar backscatter is presented in this paper. The proposed OMT is not required the additional waveguide taper structures to connect with a standard adaptor by the newly designed junction structure which bases on a waveguide taper. Total length of the OMT for L-band is about 1.2 ${\lambda}_o$(310 mm) and it's a size of 60 % of the existing OMTs. And, to increase the matching and isolation performances of each polarization, two conducting posts are inserted. The bandwidth of 420 MHz and the isolation level of about 40 dB are measured in the operating frequency. The L-band scatterometer consisting of the manufactured OMT, a horn-antenna and network analyzer(Agilent 8753E) was used STCT and 2DTST to analysis the measurement accuracy of radar backscatter. The full-polarimetric RCSs of test-target, 55 cm trihedral corner reflector, measured by the calibrated scatterometer have errors of -0.2 dB and 0.25 dB for vv-/hh-polarization, respectively. The effective isolation level is about 35.8 dB in the operating frequency. Then, the horn-antenna used to measure has the length of 300 mm, the aperture size of $450{\times}450\;mm^2$, and HPBWs of $29.5^{\circ}$ and $36.5^{\circ}$ on the principle E-/H-planes.

• Journal of Astronomy and Space Sciences
• /
• v.27 no.3
• /
• pp.239-244
• /
• 2010

A simulation for the design of a $90^{\circ}$ differential phase shifter aimed toward Korean VLBI Network (KVN) 129 GHz band polarizer is described in this paper. A dual-circular polarizer for KVN 129 GHz band consists of a $90^{\circ}$ differential phase shifter and an orthomode transducer. The differential phase shifter is made up of a square waveguide with two opposite walls loaded with corrugations. Three-dimensional electromagnetic simulation has been performed to predict the $90^{\circ}$ differential phase shifter's characteristics. The simulation for the differential phase shifter shows that the phase shift is $90^{\circ}{\pm}3.3^{\circ}$ across 108-160 GHz and the return losses of two orthogonal modes are better than -30 dB within the design frequency band. According to the simulation results the calculated performance is quite encouraging for KVN 129 GHz band application.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.13 no.2
• /
• pp.33-39
• /
• 2013

In this paper, X/Ku band waveguide diplexers with H-plane T-junction for satellite communication systems is proposed and its characteristics is cinfirmed. Two frequency bands such as X(7.25 ~ 8.4 GHz) and Ku(12.25 ~ 14.5 GHz) can be separated by the proposed waveguide diplexers. A diplexers is normally including low pass filter, high pass filter and junction waveguide. To simplify the structure of the proposed diplexers, the proposed waveguide diplexers is using impedance matching technique on H-plane of the high pass filter without low pass filter. To use vertical and horizontal polarization, the proposed diplexers with orthomode transducer(OMT) characteristics is also designed. Therefore, it is confirmed that the proposed waveguide diplexers can be used as dual-band and dual-polarization diplexers for satellite communication feed systems.