A Validity study on Dip & Vacuum Brazing
Method for Ka-band Waveguide Slot Array
Antenna
Chae-Hyun Jung1, Jong-Gyun Baek1, Kook-Joo Lee1, Chang-Hyun Park1 and Jongkuk Park1 1LIG Nex1 Co.,Ltd, 148-1, Mabuk-dong, Giheung-gu, Yongin-City, Gyeonggi-do, Republic of Korea.
Abstract - In this paper, two different fabrication methods,
which are dip-brazing and vacuum-brazing, are applied to Ka-band waveguide slot array antenna for radar system. Dip &
vacuum brazing needs a different jig design and layer composition for manufacture in the same design model. The validity of each method is verified by comparing between the
simulation and the measurement result. According to the result, it is found that both fabrication methods are available for Ka-band waveguide slot array antenna.
Index Terms — Slot array antennas, Dip-brazing, Vacuum-brazing
1. Introduction
The planar waveguide slot array antenna has frequently
been used in radar systems. Especially, it is widely applied to
airborne radars or seeker systems. This kind of system
physically needs light weight and operating in the high
power circumstance. In order to satisfy requirements,
aluminum which is a relatively light metal has usually been
chosen to make a waveguide slot array antenna.
The waveguide slot array antenna consists of multiple
layers and each layer is joined strongly together to block the
electromagnetic wave leaking by using a special fabrication
method, such as dip and vacuum-brazing. As operating
frequency is getting high, the dimension of standard
waveguide becomes small for joining. So, fabrication
method should be considered in the way that is relatively less
sensitive to the manufacturing errors which are the residue
inside waveguide after brazing and the machining error. At
Ka-band it requires much more precision machining and is
also more important to get rid of residue inside waveguide
after brazing. Due to the demand, the vacuum-brazing is
useful at Ka-band because it works in vacuum which means
there is no flux inside waveguide like the dip-brazing to
remove. But it is not easy to find the optimized vacuum
chamber operation condition at a certain design model.
In the following Section 2, by comparing between
designed data and measurement the effectiveness of the dip-
brazing antenna at Ka-band is shown[1]. Then, the vacuum-
brazing antenna is considered as well in Section 3[2]. Finally,
conclusion is given in Section 4.
2. Dip-brazing antenna
The antenna design is following the Elliott’s design
procedure[3]. In order to have above 28 dBi gain,
6.3˚ ±0.5˚ of 3dB beamwidth and below -22dB SLL(Side-
Lobe Level) at Ka-band, taylor weighting distribution in
diameter 11.66λ 0 is used and it has two channels for the
monopulse. Its performance is verified with a commercial
electromagnetic analysis tool(CST). After the design, the
fabricated antenna by the dip-brazing is depicted in Fig. 1.
(a) Front view (b) Back view
Fig. 1. Fabricated dip-brazing antenna
A comparison of the measured and simulated patterns is
given in Fig. 2. Beamwidth and SLL are similar to what
expected and the measured gain is 28.1 dBi at the center
frequency of the design bandwidth.
(a) Azimuth radiation pattern
Sum port
Del port
2018 International Symposium on Antennas and Propagation (ISAP 2018)October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea
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(b) Elevation radiation pattern
Fig. 2. Radiation pattern of the dip-brazing antenna
3. Vacuum-brazing antenna
Design values in the vacuum-brazing antenna are above 33
dBi gain, 3.5˚ ±0.5˚ of 3dB beamwidth and below -22dB
SLL in diameter 23.33λ 0.Three channels are considered for
using the monopulse technique. The fabricated antenna by
the vacuum-brazing is shown in Fig. 3.
(a) Front view (b) Back view
Fig. 3. Radiation pattern of the vacuum-brazing antenna
Its comparison of the measured and simulated patterns is
given in Fig. 4. The both is similar to the design result at
beamwidth and SLL and the gain, 33.2 dBi, is measured at
the center frequency of the design bandwidth.
(a) Azimuth radiation pattern
(b) Elevation radiation pattern
Fig. 4. Radiation pattern of the vacuum-brazing antenna
4. Conclusion
Two different waveguide slot array antennas are designed
at Ka-band. To manufacture antennas, the dip-brazing and
the vacuum-brazing are applied respectively.
In the dip-brazing the holes are applied to the end of
waveguide in antenna and the customized jig to remove the
residue cleanly. In the vacuum-brazing the optimized
vacuum chamber operation condition such as pressure and
temperature profile is found with the designed jig.
From the electrical result it is realized that both methods
are available to make the complicated structure of Ka-band
waveguide slot array antenna.
References
[1] Chae-Hyun Jung, Jong-Gyun Baek, Kook-Joo Lee, Chang-Hyun Park,
Jun-Beom Kwon, “Waveguide Broad-wall Slot Array Antenna Study for Millimeter-Wave Seeker Using Cross Monopulse Axes“, JIIBC,
pp. 209-215, Oct. 2017. [2] Jong-Gyun Baek, Chae-Hyun Jung, Kook-Joo Lee, Chang-Hyun Park,
“Waveguide Broad-wall Slot Array Monopulse Antenna for
Millimeter-Wave Seeker Using Dip Brazing Method”, KIEES, pp. 1020-1026, Nov. 2015.
[3] R. S. Elliott, Antenna Theory and Design, Prentice-Hall, 1981.
Del Az port
Sum port
Del El port
2018 International Symposium on Antennas and Propagation (ISAP 2018)October 23~26, 2018 / Paradise Hotel Busan, Busan, Korea
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