Radiation properties and ground-dependent response of compact printed sinusoidal antennas and arrays

摘要

Printed sinusoidal monopoles are enhanced meander-line antennas (MLAs). The antennas were designed in the 2.0¿3.5 GHz band according to the size and bandwidth constraints of high data-rate wireless sensor nodes. Their performance was characterised in terms of electrical size, bandwidth and broadband radiation efficiency. A suitable scalar quantity was used to capture the overall performance. Numerical results show that sinusoidal monopoles can achieve 50% fractional bandwidth (FBW), which is a 60% improvement compared to an MLA of similar size and efficiency. Antenna performance depends heavily on electrical size, which depends on the size of the ground plane; its effect on radiation was also included. Compact printed arrays built with sinusoidal monopoles were also studied. Their performance was characterised in terms of active impedance bandwidth, broadband radiation efficiency, active element pattern, mutual coupling and broadband correlation coefficient. The results showed that densely packed compact arrays feature controllable element detuning, whereas correlation coefficient stayed below 0.5 even for l/10 spacing. The computational results were supported by measurements on actual hardware. Antennas mirrored against the nominal 20 mm x 30 mm ground plane achieved FBWs in the range 23¿28%. Those that used the adapted ground plane (GNDP) size scored 24¿34% FBWs. In the case of arrays, the active impedance FBW degraded gracefully with decreasing inter-element distance from 33% to 27%.