So-hyeun Yun

Multibeam reflector antenna fed by few elements for Ka-band communication satellite

This paper presents the multibeam reflector antenna fed by array elements for Ka-band satellite communication services on the Korean Peninsula. We suggest the optimized antenna configuration, array elements and excitation coefficient. The antenna configuration is simplified by the combination of SFPB (single feed per beam) system and phased array system. Through the design, we find out the minimized number of reflectors and array elements and also show the radiation pattern of the reflector antenna system with few elements.

Ka-Band Antenna Design Using the Reflector Shaping for the Communications & Broadcasting Satellite

The electrical design of the Ka-band antenna for the domestic Communications and Broadcasting Satellite (CBS) is described. The antenna has the offset Gregorian structure and is installed on the Earth-facing panel of the satellite. The electrical performance specifications for the antenna were determined from the required EIRP and G/T through the payload level performance analysis. This paper utilized the reflector shaping technology for the trade-off among the major performance parameters, resulting in compliance of all the parameters. The designed antenna shows 37.95 dBi EOC (End of Coverage) gain and 28.7 dB sidelobe isolation for transmit band, and 37.49 dBi EOC gain and 31.1 dB sidelobe isolation for receive band, The electrical performances of the antenna have been verified via the electrical testing of a manufactured EQM (Engineering Qualification Model) antenna.

Wideband Receive Antennas of Sensor Stations for GPS/Galileo Satellite

This paper describes wideband L-band receive antennas of sensors for GPS as well as Galileo satellites. The antenna should provide small variations of the phase center and small group delay variations. In order to meet the specification on antenna gain, conical spiral antenna is considered. A conical spiral is arranged in a circular cylindrical cavity. The spiral is composed of bifilar coaxial line. These coaxial lines are matched to 50 Omega coaxial cable by using 1:4 RF transformer and balun. The antenna gain at zenith is greater than 6 dB and the minimum gain at low elevation angle is about -3 dB over lower frequency bands (El and E6 bands) but that is -3.5 dB over high frequency band (LI). The phase center variation of the antenna is less than 4.3 mm over whole operating frequency bands. The antenna has good performance characteristics.

Design of coaxial waveguide Feed horn

Dual band horn with TE11 coaxial waveguide mode was designed for the feed of the focused reflector antenna. The coaxial waveguide was adopted to simultaneously operate higher frequency and lower frequency, and to reduce the size. This paper showed the improved return loss and symmetrical pattern by matching element and dual mode. The performance of the optimized horn structure was verified thru the measurement.

Four band feed system with electrical tracking capability for Ku/Ka band bi-directional antenna

The feed system for four bands (Ku and Ka) with electrical tracking capability has been developed. The tests show that the feed system performs very well. It will be assembled the beam forming module and tested satellite tracking system, in order to be used for the mobile antenna system to be mounted on high speed trains.

Multipaction Free Ka-band Diplexer with an Asymmetric Iris

very low electrical current across the interface 3 . Therefore, an E-plane T-junction is more desirable than an H-plane T-junction in view of the RF performance. Multipaction is a discharge occurring in high power RF equipment operating under vacuum condition in the presence of free electrons. It is necessary to perform the multipaction risk analysis based on electromagnetic theory at the design phase. The high multipaction margin is obtained by inducing much smaller peak voltage in the resonator with minimum gap than the threshold voltage. The diplexer needs the additional plate, so called radiator, for radiating heat. The radiator was designed as part of one diplexer half. Adaptable tuning without disturbance of the radiator got accomplished by using an asymmetric iris in the receiving filter. It is critical to select the asymmetric iris corresponding to symmetric iris. Through the measurement results, we have found that the RF performance of the diplexer met the specifications and the design method was adequate. II. Diplexer Design for High Power Handling

Ka-band flexible multibeam antenna with improved gain and full power capability

We propose a novel design method for a Ka-band flexible multibeam antenna system to improve gain without the waste of resources. The design degrees of freedom are enhanced by the connection way of multiport amplifiers and array elements. Higher gain with full power capability was achieved by reassigning amplitude and phase of array elements based on the proper connection. The flexible antenna of 3 dB was effectively designed for normal multibeam and boosted beam.

Ka-band flexible power multibeam antenna

The multibeam antenna system including multiport amplifiers meets instantaneous traffic requirements and mitigates serious Ka-band signal attenuation due to rain. Boosting the power in a heavy rain or traffic region may cause the power loss due to limited on-board resources. We propose the novel design flow for flexible multibeam antenna to realize power efficiency improvement and negligible performance degradation. According to this design flow we achieve a power efficiency of 91% and EOC gain degradation of 0.1 dB for a 4.5 dB boosted beam.

Design of Ka band reconfigurable beam antenna using genetic algorithm

This paper presents an efficient design method based on genetic algorithm and design results for Ka band reconfigurable beam antenna composed of an array-fed reflector. The effective cost functions for the contoured beam and the boosted beams were used to find the best solution. During the optimization, it was confirmed that the average cost and the best cost were converged. The contoured beam antenna is designed with the gain ripple less than 3 dB over the coverage. The boost level greater than 7 dB for Seoul area is obtained.

Multibeam Reflector Antenna for Ka-Band Communication Satellite

This paper presents the multibeam service coverage of GEO(Geostationary Orbit) satellite and the practical antenna scheme scenarios to provide the universal communication services on the Korean peninsula. The proposed antenna systems consist of the simplest scheme and feed network so that they can be mounted on satellites. The feed networks are effectively organized according to the frequency and polarization plan. Despite simple structure, all scenarios meet the electrical performance by the optimization of feed allocation and feed excitation.