Isolation improvement in dual port cross-slot coupled patch

Dice-Five Polarization-Agile Corner-Fed Patch Array Antenna

“…7. As an alternative, the inductive mutual impedance of the crossed slots could be compensated with capacitive coupling between the terminal stubs of the microstrip feeding lines so as to increase the port isolation and accordingly improve cross-polarization [14]. It appears that an axial ratio of less than 3 dB is obtained over a 6.6 % bandwidth, which is about three times the bandwidth for a 10 dB return loss.…”

“…In this connection, it is observed that cross-polarized radiation could possibly be reduced by feeding the slots in a fully balanced configuration, which would imply as a drawback the adoption of a more complicated multi-layered structure for the feed, such as those proposed in [12] and [13] for a single patch. As an alternative, the inductive mutual impedance of the crossed slots could be compensated with capacitive coupling between the terminal stubs of the microstrip feeding lines so as to increase the port isolation and accordingly improve cross-polarization [14].…”

Wideband polarization-agile planar microstrip patch array antenna

“…For reduced antenna complexity, both of the two 50 Ohm microstrip feed lines are accommodate on the same layer, and each arm of the crossed slot is offset-fed, which unfortunately compromises the balance of the feed and causes aperture cross-coupling. To recover adequate port isolation and, correspondingly, a satisfactory cross-polarization performance, the terminal stubs of the feed lines are brought side by side, so that the ensuing capacitive coupling helps compensating for the inductive mutual impedance of the crossed slots [6]. The radiating part includes four square corner-fed stacked patches suitably connected to a central aperture-coupled stacked patch to form a five-of-dice array configuration.…”

“…In one of these, simplicity is favoured over a more elaborate design, and a single-layer feed network is employed, which implies breaking the symmetry of the antenna. To counteract the resulting loss of isolation between the antenna ports, capacitive coupling between the terminal stubs of the feed lines is applied [6], which helps to substantially preserve cross-polarization performance. Indeed, fairly low cross-polarized radiation components are obtained also by virtue of the symmetric arrangement devised for the radiating part of the antenna, which implements a sort of antiphase feeding technology.…”