[asac][almanews] ALMA Memo 468 Released

[Stacy Oliver]

ALMA MEMO #468

Designs of Wideband 3dB Branch-line Couplers for ALMA Bands 3 to 10

Hiroya Andoh (Toyota National College of Technology),
Tetsuhiro Minamidani, Norikazu Mizuno, Akira Mizuno, Yasuo Fukui (Nagoya University),
Shin'ichiro Asayama, Yoshinori Yonekura, Hideo Ogawa (Osaka Prefecture University)

2003-07-07

Keywords: ALMA bands 3 to 10, wideband waveguide quadrature hybrid, wideband waveguide 3dB 5-branch-line coupler, numerical matrix
analysis, S-matrix

A guiding principle of design of wideband waveguide 3-dB 5-branch-line couplers for
ALMA bands 3 to 10 in suitable for use in SSB heterodyne receivers, their designs
and their performances are reported. The couplers have good performances, which
maintain an amplitude balance to within 1dB and a phase difference of 89-91 degrees
over the frequency range of each ALMA band. The couplers for the ALMA band 3, 4, 5,
6, 7, 8, 9 and 10 include WR-10, WR-6, WR-5, WR-3, WR-2.8, WR-2.2, WR-1.5 and WR-1.2
waveguides, respectively. The couplers are designed by a numerical analytical method
by using matrices based on the circuit theory and they are optimized with 3D EM
simulator (HFSS). The numerical analytical method for seeking S-matrices mentioned in
this memo enables quick calculations for performances of 3-dB branch-line couplers in
the case of optimization and possesses advantages over electromagnetic simulation
software in common use.

View a pdf version of ALMA Memo #468.
http://www.alma.nrao.edu/memos/html-memos/alma468/memo468.pdf

Download a postscript version of ALMA Memo #468.
http://www.alma.nrao.edu/memos/html-memos/alma468/memo468.ps

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