韓國電磁波學會論文誌 第 19 卷 第 1 2008 1號 年 月 2007-19-1-12論文

87

론.

sequential

lobing simultaneous lobing

, simultaneous lobing

. Sequential simultaneous

.

,

(simultaneously) [1].

RF

. Folded reflectarray

pa-

rabolic ,

Folded Reflectarray 94 GHz

High-Gain 94 GHz Monopulse Antenna Using Folded Reflectarray

이한승 채희덕 종훈 남상욱

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 33.5 dB, elevation 27.2 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, 33.5 dB and

27.2 dB at sum mode, azimuth mode, and elevation mode respectively.

Key words : Monopulse, Reflectarray, Folded Reflectarray, Antenna, Comparator

This work was supported by SamsungThales R&D Team.

.

(School of Electrical Engineering, INMC, Seoul National University)

* (Samsung Thales)

: 20071217-147

: 2008 1 22

韓國電磁波學會論文誌 第 19 卷 第 1 2008號 年 1月

88

그림 1.

Fig. 1. The antenna layout.

.[2]. folded reflectarray

60 GHz 77 GHz

, [3].

folded reflectarray

. 1 folded reflectarray

.

feed horn polarizing grid

reflectarray ,

90 polarizing

grid . 90

polarizing grid

.

. 2005

, [4].

comparator ,

. 94 GHz

reflectarray polarizing grid

. ,

comparator feed

horn .

folded reflectarray ,

.

. Reflectarray

(a) (b)

그림 2. (a) , (b)

Fig. 2. (a) Periodic patch structures, (b) Phase results.

Reflectarray

.

. Reflectarray

,

90 . Feed horn

m reflectarray

reflectarray

ml mlk0-

. reflectarray

mf mmlk f+- 0 ,

reflectarray

, (1) feed

horn

. N , f

.  

fpf +=+- Nlk mm 20 (1)

,

.

reflectarray . , re-

flectarray 90

45

mf ,

pf +m .

Folded Reflectarray 94 GHz

89

그림 3. Reflectarray

Fig. 3. Layout of reflectarray.

(a) (b)

그림 4. (a) Slot polarizing grid , (b)

Fig. 4. (a) Structure of slot type polarizing grid (b)

Unit cell.

reflectarray (1)

180

90

.

2

, 94 GHz

. Eward

Floquet[5] [7]

. 3 reflectarray .

. Prolarizing Grid

Polarizing grid

.  Polarizing grid slot

dipole

, 4

(a) (b)

(a) Unit cell (b) Simulation result

그림 5. Polarizing Grid

Fig. 5. Simulation results of polarizing grid.

(a) (b)

그림 6. (a) Polarizing grid , (b)

Fig. 6. (a) Photograph of polarizing grid, (b) Magni-

fied photograph.

slot

. slot

,

,

. ,

,

.

MOM 5

polarizing grid

. 6 polarizing grid

.

. Comparator Using Circular Cavity Hybrid

comparator feed horn 4 port

韓國電磁波學會論文誌 第 19 卷 第 1 2008號 年 1月

90

그림 7. Cylindrical cavity TE111

Fig. 7. Cylindrical cavity structure and its TE111 re-

sonant mode.

sum port, azimuth port, elevation

port 3 .

Comparator 4 hybrid ,

cylindrical cavity hybrid[8]. 7 , cylindrical cavity

TE111 45° 135°

180° . hybrid

cavity cavity

reactive

step ,

.

8 comparator

(a) comparator

(a) Photograph of fabricated comparator

(b) Comparator

(b) Layout of comparator

그림 8. Circular cavity comparator

Fig. 8. Comparator using circular cavity hybrid.

. Comparator 94 GHz ,

3.2 mm .

waveguide

,

. Comparator 4 port

feed horn ,

. 4 port ter-

mination , 3 sum, azimuth,

elevation channel[9].

9 Comparator

S-parameter magnitude 8 GHz

. port 4

port port

1/4 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°

그림 9. comparator S-parameter magnitude

Fig. 9. Measured S-parameter(magnitude) of the com-

parator.

Folded Reflectarray 94 GHz

91

(a) (b)

(a) (b)

(c) (d)

(c) (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 cri-

terion of null depth( 20 dB).

Port 5 Port 6 Port 7 Port 8

Magnitude(±1 dB)90.5

99.7

91.5

98.8

86.7

98.1

92.5

97.6

Phase(±10°)90.4

100.6

89.9

98.1

91.2

95.3

92.5

96.3

port .

1 Comparator 20 dB null depth

bandwidth

. 1

comparator 94 GHz 3.8 GHz band-

width .

. Multimode Feed Horn

feed horn sum ,

azimuth , elevation

.

feed horn ,

[10].

11 feed horn

, feeding

. 11

,

韓國電磁波學會論文誌 第 19 卷 第 1 2008號 年 1月

92

그림 11. Feed horn

Fig. 11. Picture and layout of feed horn.

그림 12. feed horn

Fig. 12. Photograph and layout of multimode feed horn.

(a) Sum (b) Azimuth (c) Elevation

(a) Sum mode (b) Azimuth mode (c) Elevation mode

그림 13. Feed Horn far field

Fig. 13. Far field patterns of multimode feed horn.

feed horn aperture

.

feed horn .

12 feed horn

, 13 feed horn sum,

azimuth, elevation far field

.

. Antenna Performance

14 reflectarray, polarizing

grid, comparator, feed horn

, W-band

(a)

(a) Front and profile pictures of the antenna

(b)

(b) Photograph of measuring the antenna patterns

그림 14.

Fig. 14. Photograph of the antenna and the measure-

ment.

. 15 W-band

sum ,

Half Power Beamwidth(HPB) azimuth

elevation 1.5° .

directivity ,

Ddd

58.415.15.1

400,32400,32

21

0 =´

=QQ

@ dB(2)

(2) 41.58 dB

. 36 dB 5 dB

.

16 azimuth eleva-

tion , gain 33.5 dB 27.2

dB . Azimuth , sum 2.5

dB , elevation 8.8

dB . feed horn

Folded Reflectarray 94 GHz

93

(a) azimuth sum

(a) Sum pattern of the antenna(azimuth direction)

(b) elevation sum

(b) Sum pattern of the antenna(elevation direction)

그림 15. sum

Fig. 15. Far field patterns of the antenna in the sum

mode.

elevation azimuth

.

결 론.

94 GHz ,

folded

reflectarray .

reflectarray, polarizing grid, comparator,

feed horn ,

.

, 5.26 cm .

(a) azimuth

(a) Azimuth pattern of the antenna

(b) elevation

(b) Elevation pattern of the antenna

그림 16. azimuth, elevation

Fig. 16. Far field patterns of the antenna in the azi-

muth and elevation mode

power .

W-band

RF

.

참 고 문 헌

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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.

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shilded and periodic microwave structures using

Ewald sum technique", Ph. D. dissertation, Univ.

Seoul National, Seoul, Korea, 1998.

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1999 2 : (

)

2001 2 : (

)

2001 : (

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monopulse comparator using circular cavity hy-

brid", MINT-MIS2007/TSMMW2007/MilliLab Work-

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1985 2 : ( )

2002 2 : KAIST ( )

1985 1 2002 9 : LG

2002 10 2004 10 :

2004 11 :

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( )

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Austin ( )

2001 2 2002 1 : Univer-

sity of California, San Diego

:

주 심분야[ ] Microwave & Millimeterwave Active/Passive

Circuit Design