衛星放送 受信用 移動體 搭載型 自動追跡 안테나 시스템에 關한 硏究

Abstract

In this dissertation, a DBS (Direct Broadcasting from Satellite) reception system mounted on vehicle is proposed and implemented, which is composed of the slotted waveguide array antennas, the satellite tracking mechanical gear part, antenna position control circuits to track satellite signal. The antenna for mobile DBS reception is automatically controlled by the tracking algorithm with high resolution. Then, the characteristics of the auto-tracking antenna system for the DBS reception with high quality in a driving vehicle. As a result, the performance of the proposed system mounted on a car and a ship has been confirmed by the field test. To achieve the above purpose, the methods of antenna design including waveguide feeder and antenna beam tilting angle control, IF coupling circuit design to prevent a twist of feed line between antenna and tracking control circuit, and development of the high resolution algorithm to improve the tracking speed and the stability are proposed and studied in detail.

~This dissertation is composed of six chapters. The substance for each chapter is as follows

~Chapter 1 describes a antenna history for the DBS reception and a background including research target of this study.

~Chapter 2 presents a design for a single-layer feeder waveguide array using π-junctions with the inductive wall. The feed structure consists of a single waveguide placed on the same layer as radiating waveguide and is characterized by a unit divider, called a π-junction. This π-junction with an inductive wall splits part of the power into two branches waveguide through one coupling window, and can excite densely arrayed waveguide at equal phase and amplitude. The power dividing characteristics of the cascade of π-junctions are analyzed by Galerkin's method of moments. The numerical results show reasonable agreement with the experimental results. From the optimum simulation results based on the feeder waveguide using π-junction,~the scattering matrices of the feeder divided power are obtained. It can be applied for 2n-way power divider.

~In the Chapter 3, the 16-port feed waveguide array with inductive walls analyzed by Galerkin`s method of moments are proposed for the DBS reception system mounted on vehicle. First of all, in order to verify the validity of electromagnetic analysis and design for a π-junction feed waveguide, it is designed and fabricated at DBS band. The measurement results of a π-junction feed waveguide agree well with the theoretical ones. Based on this design method, an array design for WR-90 standard waveguide is conducted. Since the width of a π-junction feed WR-90 standard waveguide is larger than a guided wave length in an array design, the difference of amplitude and phase of 8-port array are calculated 2.3 dB and 62 degrees, respectively. The bandwidth with return loss of -20 dB below is about 220 MHz and it doesn't satisfy DBS band. To solve this problem, we propose a novel design that the width of a π-junction feed waveguide equals to a guided wave length. By the proposed novel design for 8-port feed waveguide array, the difference of amplitude and phase are decreased 1 dB and 13 degrees, respectively. The broad bandwidth of 700 MHz is also realized. The size of 16-port waveguide array compared with WR-90 array is reduced about 10 cm. The measured antenna gain for the fabricated 16-port feed waveguide array is observed 24 dBi above at DBS band.

~Chapter 4 describes the characteristics of beam-tilting slot array waveguide~antennas and super low noise LNB for mobile DBS reception. As a basic study of slotted waveguide array, design for 16 slot elements located on a broad-wall waveguide is considered. Design parameters such as slot length, space between each slot and cross slot angle of antennas with the beam-tilting characteristics are calculated by method of moments. Based on these results, the radiation waveguide antennas with 16-element × 16-array are designed and fabricated. The measured main beam direction angles of the fabricated antennas are 48° to 50° depending on the measured frequencies and it shows good agreement with prediction. The measured 3 dB beam width of elevation pattern is about 13°, and the axial ratio and the gain measured at DBS band are observed 2.8 dB below and 24 dBi above, respectively. The high performance LNB is also designed and fabricated. It has a conversion gain of 65 dB, a gain flatness of 2 dBp-p, a noise figure of 0.7 ~ 0.9 dB, and a phase noise of about -100 dBc/Hz at 100 kHz. In order to evaluate a performance of the fabricated waveguide planar antenna and super low noise LNB, it is combined with the satellite tracking control system and the field performance test of antenna mounted on a mobile vehicle is carried out at highway. During the measurement, we confirmed that it was possible to watch television without a break signal in a driving vehicle and an excellent performance of the proposed antennas and LNB was demonstrated.

~Chapter 5 describes the performance of a satellite tracking antenna control system for mobile DBS reception and the characteristics of IF coupling circuit for prevention of wire twist occurred by system turn. In order to improve the tracking speed and the stability of this system, a directional sensor function is added to a conventional left-right tracking algorithm. The satellite tracking experiments of the fabricated antenna system for the DBS reception have been performed at a highway and an urban area. The measured AGC signal level on the highway was observed above the level to watch television. Therefore, an excellent performance of the hardware system with the tracking algorithm compensated for the directional sensor was confirmed.

~Chapter 6 describes an important summary of~the research results for leaky-wave slotted array waveguide antenna, super low noise Ku-band LNB, auto tracking control circuit and algorithm, and field test of the proposed DBS reception system.