Time-domain performance of a patch-loaded band-reject UWB antenna

A previous study of a novel technique to design a band-reject UWB monopole antenna by using patch loading is extended. Frequency-domain measurements have confirmed that the antenna designed using this technique rejects the interfering signal at the two intended narrowband frequency ranges. Moreover, the antenna radiation pattern distortion is negligible except at the notched bands. A study of time-domain characteristics based on the antenna pulse response and system fidelity factor is presented. The time performance has been extracted from frequency-domain measurements using a standard method. The obtained time-domain results promise the suitability of the proposed technique to design band-reject antennas useful for future UWB system applications.

A novel, low-profile, vertically-polarized UWB antenna for WBAN

Mohsen Koohestani, Anja Skrivervik Favre, Jean-François Zürcher

This paper proposes a novel, low-profile UWB antenna for wireless body area network (WBAN) applications. The antenna has a polarization perpendicular to the body-free-space interface, which is interesting in order to minimize the coupling into the body. Its structure comprises a modified mono-cone with a top-cross-plate and is coaxially fed through the ground plane. The higher frequency band |S11| performance is due to the mono-cone while the top-cross-plate is responsible for the lower frequency band. This plate also leads to a height reduction when compared to conventional mono-cone antennas. A comprehensive parametric study is done to provide design guidelines. Both frequency- and time-domain results have been measured and presented to validate the design. Results show that the antenna operates from 3.06 to beyond 12 GHz based on |S11| ≤ -10 dB, radiates omni-directionally in the H-plane, and has a radiation efficiency over 95%. The system-fidelity factor for UWB signals is adequate for pulse transmission. Finally, the influence of the human proximity on the antenna matching was tested. Results show that its impedance is nearly unchanged as compared to free-space.

Institute of Electrical and Electronics Engineers2014

Optimization of an acoustic leaky-wave antenna based on acoustic metamaterial

Sami Driss Karkar, Hervé Lissek, Seyyed Hussein Seyyed Esfahlani

In recent years, an increasing number of pioneering studies have been carried out in the field of acoustic metamaterials, following the path of electromagnetic metamaterials. These artificial engineered materials are designed in such a way so as to achieve new macroscopic properties, like negative refraction, that are not readily present in nature. While the design and the fabrication of these artificial materials is a hot topic among scientists in different fields of physics such as photonic, electromagnetic, acoustic and recently mechanic, an important part of the scientific research is now oriented towards the identification of actual applications for these structures. As the novel idea of metamaterial was first developed in the electromagnetic realm and for the microwave frequency range, it is somehow more mature in these fields than in acoustics. Metamaterial applications are now widely developed in electromagnetics especially for the design of new antenna. Among other examples, metamaterial concepts are aiming at reducing the coupling between two adjacent radiating elements of the array and increasing the operating bandwidth of radiating elements. It is also used for phase compensation in microwave transistors, and many more applications are rising in the recent literature. In year 2009, in analogy with electromagnetic transmission line metamaterial, our group proposed a concept of acoustic transmission line metamaterial, consisting of a waveguide periodically loaded with membranes along the duct, and transverse open channels (denoted “stubs”). Based on our proposed structure and in analogy with applications of transmission line electromagnetic metamaterials, researchers proposed the idea of an acoustic counterpart to the “backward wave antenna”. These antennas or radiating devices have a very special property such that the radiation angle or the directivity changes with the frequency. In this article, a comprehensive, step by step, design methodology for acoustic backward wave antenna is presented. For this purpose we use the model proposed in our 2009 publication for acoustic transmission line metamaterial, but we focus the discussion on the optimization of the antenna performance. We also propose some closed form formulas for the practical design of such devices, and a formal validation of the structure is proposed using Comsol Multiphysics.

2013

Design and Measurement of a Differential Printed Antenna for a Wireless Sensor Network Node

Nuno Miguel Faria Pires, Anja Skrivervik Favre

This letter presents the design and measurement of an antenna integrated into an agricultural sensor network node operating on the 2.4-GHz ISM band using the ZigBee protocol stack. The novel structure, coined bowtie-shaped folded dipole (BSFD), has a differential 100-Omega input impedance matching a particular controller widely used in wireless sensor network (WSN) applications. This letter also presents a survey of existing WSN antennas to which the proposed design compares favorably. The challenges of testing a differential antenna using conventional single-ended equipment are addressed regarding antenna impedance and radiation pattern measurements. The differential antenna input impedance was confirmed with four different test setups using a conventional vector network analyzer. The radiation pattern of the proposed antenna was measured in-prototype resorting to a spectrum analyzer. The measured patterns show that the proposed antenna has a maximum received power over 4 dB compared to two early versions of the WSN node that used commercial off-the-shelf antenna solutions. The performance was also confirmed in a field test where a BSFD-equipped prototype achieved close to a 300-m range, tripling that typical for ZigBee applications.

Ieee-Inst Electrical Electronics Engineers Inc2017

Optimization of an acoustic leaky-wave antenna based on acoustic metamaterial

Sami Driss Karkar, Hervé Lissek, Seyyed Hussein Seyyed Esfahlani

2013