Low-frequency inverted-F antenna on annular ground plane

Nishiyama, Naoto; Michishita, Naobumi; Morishita, Hisashi

doi:10.1109/imws-bio.2015.7303819

Cited by 3 publications

(3 citation statements)

References 4 publications

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“…Wearable helmet-mounted antennas were proposed for disaster prevention [25] and military forces [26]. The more common helmet antennas are dipoles [27], [28], patches [26], and loops [29]. Noticeably, as stated in Table I, a LoRa UAVwearable device link [30] has never been neither characterized nor modeled.…”

Section: This Workmentioning

confidence: 99%

Numerical and Experimental Characterization of LoRa-based Helmet-to-UAV links on Flat Lands

Bianco,

Mejia-Aguilar,

Marrocco

2022

Preprint

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The use of the LoRa communication protocol in a new generation of transceivers is attractive for search and rescue (SaR) procedures because they can operate in harsh environments covering vast areas while maintaining a low power consumption. The possibility of wearing helmets equipped with LoRa-radios and installing LoRa transceivers in unmanned aerial vehicles (UAVs) will accelerate the localization of the targets, probably unconscious. In this paper, the achievable communication ranges of such links are theoretically and experimentally evaluated by considering the possible positions of the helmet wearer (standing or lying) on a flat field, representing a simple SaR scenario. Simulations and experimental tests demonstrated that, for the standing position, the ground-bounce multi-path produces strong fluctuations of the received power versus the Tx-Rx distances. Such fluctuations can be kept confined within 100 m from the target by lowering the UAV altitude. Instead, for a more critical lying position, the received power profile is monotonic and nearly insensitive to the posture. For all the considered cases, the signal emitted by the body-worn transceiver can be exploited to localize the helmet wearer based on its strength, and it is theoretically detectable by the UAV radio up to 5 km on flat terrain.

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Section: This Workmentioning

confidence: 99%

Numerical and Experimental Characterization of LoRa-based Helmet-to-UAV links on Flat Lands

Bianco,

Mejia-Aguilar,

Marrocco

2022

Preprint

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“…A number of antennas specifically designed for helmets have been presented in the literature (e.g. [12][13][14][15][16][17][18][19][20][21][22]). In [12], a low-profile antenna with a conical radiation pattern was realised by combining a four-element slot antenna array with an AMC surface, but this design had a limited bandwidth (25.6% for S 11 < − 10 dB).…”

Section: Introductionmentioning

confidence: 99%

“…A number of VHF helmet antennas have been demonstrated [17][18][19]. These antennas, which are based on planar inverted-F antennas, planar inverse L-shape antennas, or folded dipoles, have a very narrowband response around 150 MHz and thus these designs are not suitable for the broadband applications considered in this paper.…”

Section: Introductionmentioning

confidence: 99%

Broadband body‐worn antenna using a top‐loaded pyramidal radiator

Jackson

Merkley²

2020

IET Microwaves, Antennas & Propagation

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A wide‐bandw idth low‐profile quasi‐omnidirectional antenna is presented and experimentally demonstrated when integrated with a helmet for emergency services or military applications. The antenna consists of a pyramid‐shaped radiator that is top‐loaded with an etched copper‐clad microwave laminate with two shorting strips used to improve the input impedance matching, particularly for lower frequencies. The design and operation of the antenna are first introduced using a flat ground plane, and then experimental results are reported when it is installed on a helmet where the outer surface of the helmet is used as the ground plane. The results show a very wide impedance bandwidth from 890 MHz to 13.7 GHz (VSWR ≤ 3) and predominately monopole‐like radiation patterns up to ∼11 GHz. The antenna has a height of λ/16 at the lowest operating frequency of 890 MHz (21 mm). Simulation results with a human body model demonstrate the significantly improved omnidirectionality of the proposed helmet antenna compared to more conventional body‐worn antennas used in some applications.

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