Simulation and experimental results: Microstrip power dividers on
Rogers 5880 substrate with thickness of 0.254mm are designed for the
measurement of the multi-port interconnected ME dipole antenna array
under one balanced port excitation and four port excitation as a
circularly polarized antenna. The photograph of the fabricated antenna
and the power dividers are shown in Fig. 2. An end-launch connector
(Qualwave QELC-KF-3) is used to feed the antenna array.
The simulated and measured results for the multi-port interconnected ME
dipole antenna array excited at one balanced port with power divider and
for the two-balanced-port excitation are shown in Fig. 3. The -10 dB
impedance bandwidths are 12.14% (25.4–28.8 GHz) and 12.8% (24.6-28.2
GHz) for simulated and measured one balanced port excitation,
respectively. The simulated -10 dB impedance bandwidths is 48.57%
(22.4–36 GHz). It should be mentioned that the simulated isolation
between two balanced ports is lower than -15dB which enables the
proposed antenna array to support the simultaneous reception of two
orthogonal polarizations or transmission in either of these
polarizations. For one-balanced-port excitation, the maximum realized
gain is 13.52 dBi at 27 GHz for both simulation and measurement, and the
measured 3-dB gain bandwidth is 4 GHz from 25.25 to 29.25 GHz (or
14.29% at 28 GHz), while the simulated 3-dB gain bandwidth is 5.25 GHz
from 24.75 to 30GHz (or 18.75% at 28 GHz). The co-polarized fields are
higher than their cross-polarized counterparts by more than 10 dB both
simulation and measurement, which indicates a pure linear polarization.
Fig. 4 shows the current distribution when port 1 and port 4 are excited
with the same amplitude and with the phase of 0o and
180o. The instantaneous currents are almost in phase
on the ME dipole radiators. The elements far away from port 1 and port 4
are excited as well due to the interconnected structure, which leads to
a high antenna gain.