韓國電磁波學會論文誌第 19 卷第 1 號 2008年 1月論文 2007-19-1-12 Folded Reflectarray 94 GHz High-Gain 94 GHz Monopulse Antenna Using Folded Reflectarray 이한승채희덕전종훈남상욱 Hanseung Lee Heeduck Chae Jonghoon Chun* Sangwook Nam 요 약 94 GHz folded reflectarray folded reflectarray polarizing grid reflectarray feed horn comparator feed horn comparator sum azimuth elevation sum 36 db azimuth 335 db elevation 272 db Abstract This paper proposes a high-gain monopulse antenna using the folded reflectarray for a monopulse target-tracking radar systems designed at the center frequency of 94 GHz In target-tracking radar systems the angle of arrival of the incoming wave is determined by comparing the signal received on two or more non-coincident antenna patterns This is the physical basis of most target-tracking techniques and the comparison is made simultaneously in a monopulse radar systems In this paper the antenna consists of polarizing grid reflectarray multimode feed horn and comparator implemented by waveguide The antenna is able to have three radiation patterns by using the monopulse feed systems assembled by multimode feed horn and comparator The antenna demonstrates maximum gains 36 db 335 db and 272 db at sum mode azimuth mode and elevation mode respectively Key words : Monopulse Reflectarray Folded Reflectarray Antenna Comparator lobing 서론 sequential simultaneous lobing simultaneous lobing Sequential simultaneous (simultaneously) RF Folded reflectarray parabolic [1] This work was supported by SamsungThales R&D Team (School of Electrical Engineering INMC Seoul National University) * (Samsung Thales) : 20071217-147 : 2008 1 22 87
韓國電磁波學會論文誌第 19 卷第 1 號 2008年 1 月 그림 1 Fig 1 The antenna layout 60 GHz 77 GHz folded reflectarray [2] folded reflectarray 1 folded reflectarray feed horn [3] polarizing grid reflectarray 90 polarizing grid 90 polarizing grid 2005 [4] 그림 2 Fig 2 Periodic patch structures Phase results fm horn Reflectarray 90 Feed horn m reflectarray lm reflectarray reflectarray reflectarray Reflectarray - k l 0 m - k 0 l m + fm (1) feed N f - k0 lm + f m = 2pN + f (1) comparator 94 GHz reflectarray polarizing grid comparator feed horn folded reflectarray Reflectarray reflectarray reflectarray 90 f m f + p m 45 88
Folded Reflectarray 94 GHz 그림 3 Reflectarray Fig 3 Layout of reflectarray Unit cell Simulation result 그림 5 Polarizing Grid Fig 5 Simulation results of polarizing grid 그림 4 Slot polarizing grid Fig 4 Structure of slot type polarizing grid Unit cell reflectarray (1) 2 90 180 94 GHz Eward Floquet [5] [7] 3 reflectarray Polarizing grid Prolarizing Grid Polarizing grid slot dipole 4 그림 6 Polarizing grid Fig 6 Photograph of polarizing grid Magnified photograph slot slot MOM 5 polarizing grid 6 polarizing grid Comparator Using Circular Cavity Hybrid comparator feed horn 4 port 89
韓國電磁波學會論文誌第 19 卷第 1 號 2008年 1 月 그림 7 Cylindrical cavity TE111 Fig 7 Cylindrical cavity structure and its TE111 resonant mode sum port azimuth port elevation port 3 Comparator 4 hybrid cylindrical cavity hybrid [8] 7 cylindrical cavity TE111 45 135 cavity 180 hybrid reactive step 8 comparator cavity Comparator 94 GHz 32 mm waveguide Comparator 4 port feed horn 4 port termination 3 sum azimuth elevation channel [9] 9 Comparator S-parameter magnitude port 8 GHz port 4 1/4 port port port port power 6 db 1/4 10 Phase delay port 6 4 port port 6 4 port ( sum port plate ) port 5 port 1 port 2 port 3 port 4 180 comparator Photograph of fabricated comparator Comparator Layout of comparator 그림 8 Circular cavity comparator Fig 8 Comparator using circular cavity hybrid 그림 9 comparator S-parameter magnitude Fig 9 Measured S-parameter(magnitude) of the comparator 90
Folded Reflectarray 94 GHz (c) (c) (d) (d) 그림 10 Comparator Fig 10 Measured S-parameter(phase) of the comparator port 5 port 1 port 2 port 3 port 4 azimuth port 5 azimuth port Port 8 port 1 port 3 port 2 port 4 180 port 8 port 1 port 3 port 2 port 4 elevation port 8 elevation 표 1 Null depth 20 db comparator Table 1 Bandwidth of the comparator from the criterion of null depth( 20 db) Magnitude(±1 db) Phase(±10 ) Port 5 Port 6 Port 7 Port 8 905 997 904 1006 915 988 899 981 867 981 912 953 925 976 925 963 port 1 Comparator 20 db null depth bandwidth 1 comparator 94 GHz 38 GHz bandwidth Multimode Feed Horn feed horn sum azimuth elevation feed horn [10] 11 feed horn feeding 11 91
韓國電磁波學會論文誌第 19 卷第 1 號 2008年 1 月 그림 11 Feed horn Fig 11 Picture and layout of feed horn Front and profile pictures of the antenna 그림 12 feed horn Fig 12 Photograph and layout of multimode feed horn Photograph of measuring the antenna patterns Sum Azimuth (c) Elevation Sum mode Azimuth mode (c) Elevation mode 그림 13 Feed Horn far field Fig 13 Far field patterns of multimode feed horn feed horn feed horn aperture 12 feed horn 13 feed horn sum azimuth elevation far field grid comparator Antenna Performance 14 reflectarray polarizing feed horn W-band 그림 14 Fig 14 Photograph of the antenna and the measurement sum 15 W-band Half Power Beamwidth(HPB) elevation 15 D 32400 32400 0 @ = = Q1 dq2d 15 15 (2) 4158 db azimuth directivity 4158 db 36 db 5 db (2) 16 azimuth elevation gain 335 db 272 db Azimuth sum 25 db elevation 88 db feed horn 92
Folded Reflectarray 94 GHz azimuth sum Sum pattern of the antenna(azimuth direction) azimuth Azimuth pattern of the antenna elevation sum Sum pattern of the antenna(elevation direction) 그림 15 sum Fig 15 Far field patterns of the antenna in the sum mode elevation 결 론 reflectarray azimuth 94 GHz reflectarray polarizing grid comparator feed horn folded 526 cm elevation Elevation pattern of the antenna 그림 16 azimuth elevation Fig 16 Far field patterns of the antenna in the azimuth and elevation mode power RF W-band 참고문헌 [1] D R Rhodes Introduction to Monopulse New York: McGraw-Hill pp 2-7 1959 [2] D Pilz W Menzel "Folded reflectarray antenna" Electron Lett vol 34 no 9 pp 832-833 Apr 1998 93
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