Co-design of Antenna Element and Ground Plane for Printed Monopoles Embedded in Wireless Sensors

Abstract

This work presents the results of a study onEuclidean and fractal small antennas operating in the 2-3 GHz range, which were designed according to the size and bandwidth constraints imposed by wireless multimedia sensor networks. The performance of small antennas depends heavily on their electrical size, which is controlled by the size of the ground plane. We cannot design small antennas for tiny sensor nodes without considering the effect of the ground plane. The tested schemes have been characterized in terms of electrical size, fractional VSWR bandwidth, and broadband total radiation efficiency. A suitable Figure-of-Merit is also suggested, which is an attempt to gather all fundamental antenna parameters in a single scalar quantity. The results show that a large ground plane does not necessarily produce a better printed antenna. Moreover, each antenna element couples to the ground plane in its own unique way. Meander-line antennas manage to outperform more involved antenna configurations in a fair comparison.

Small printed sinusoidal antennas: A simple design guide for smooth meander-line structures with augmented bandwidth

“…To quantify this trade-off, we used (2) as a Figure-Of-Merit (FOM) for our antennas. The goal of the designer is to come up with configurations that produce the largest possible ratio [4].…”

“…The FOM is a pure number expressed in deciBels. For further details on the FoM and the rationale behind total e , the reader is referred to [4]. Each of the presented antennas operates around 2.5 GHz, where λ 0 = 120 mm.…”

“…1). The problem is that the behaviour of such printed monopoles is far more sensitive to the changes in subW than to the changes in subL [4]. Therefore, we chose to fix the values of subW for every GNDP in a way that implements non-resonant antennas (a BW-oriented approach).…”

“…Thus, printed antennas, which are inherently 2-D structures, seem a priori handicapped. However, it has been shown that printed meander-line antennas (MLAs) can function as small efficient radiators [4]. Herein, a re-invention of the MLA is proposed: By shaping the meander like a smooth sinusoidal curve, we obtained small antennas that can easily produce a second frequency-adjacent resonance and thus greatly improve their bandwidth.…”

Throughput-Based Antenna Selection Measurements

“…1). The receive antennas are printed monopole elements [38,39] that were designed according to the generalized Koch pre-fractal curve with a resonation frequency equal to 2.7 GHz and bandwith greater than 400 MHz.…”