TITLE:
A Linear Array Antenna of Microstrip Patch Antennas Fed by the Open-End of Coplanar Waveguides
AUTHORS:
Toshihisa Kamei, Hiromi Shima, Syotaro Fukuda, Seishiro Ishii
KEYWORDS:
Microstrip Patch Antenna, Coplanar Waveguide, Linear Array Antenna, Short Stub, Undesired Resonance Suppression
JOURNAL NAME:
Wireless Engineering and Technology,
Vol.8 No.2,
April
14,
2017
ABSTRACT: In this
study, we constructed a 4-element linear array antenna using four 20 GHz band
microstrip patch antennas with a structure such that the signal is fed to the
patch antennas from open-end coplanar waveguides without contact. We
investigated factors related to the design of linear array patch antennas. To adjust
the maximum radiation direction and reduce return loss, we optimized the
spacing between the elements and their shape. With an element spacing of 11.50
mm, patch width of 3.90 mm, and patch length of 4.15 mm, we obtained a
resonance frequency of 20.05 GHz and a return loss of -29.59
dB at the resonance frequency. However, in the case of a 4-element linear array
antenna structure, undesired resonances occurred in frequency bands other than
the design resonance frequency band of 20 GHz. To suppress these undesired resonances
and obtaining stable operation at the design frequency, we propose a new
structure in which the feed line is
loaded with a short stub, and show through computer simulations that the
occurrence of undesired resonances can be sufficiently suppressed. Furthermore,
we demonstrate the problem of radiation gain reduction caused by introducing a
short stub, propose a design method for a new structure in which the feed line has slits between the
stubs, and show improvement of the antenna gain by 0.5 dBi.