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This paper presents a small truncated waveguide fed by a microstrip line through a transverse coupling slot for multi-band WLAN applications. The proposed radiating element allows to obtain a high radiated power, with a very low cross-polar component in the radiated field, with a −10 dB bandwidth that covers the required frequencies for multi-band WLAN applications (5.2/5.4/5.8 GHz).
The problem of detecting and localizing “thin” metallic scatterers from electromagnetic scattered field measurements is addressed. The scatterers are assumed to be infinitely long and a 2-dimensional mathematical model is adopted. According to the distributional approach, the problem is cast as the inversion of a linear integral operator acting on δ-distributions whose supports are representative...
This work presents the design and simulation of a 6 GHz to 13 GHz Archimedean spiral antenna loaded with dielectric plates. Two dielectric plates separated by an air gap placed precisely on the Archimedean spiral antenna. The dielectric plates are made up of FR-4 dielectric material (dielectric constant 4.3 and loss tangent 0.025). It is found that, after the placement of the dielectric plates, directivity...
A differential amplifier feeding a balanced antenna is investigated experimentally. This approach would suit modern RFIC design rather than using a 50Ω unbalanced connection. As such the balun or power-combining network is eliminated resulting in a compact RF front-end design with wider bandwidth and lower losses. Experimental result shows that this technique promises higher output power compared...
This paper characterizes coplanar waveguide (CPW) lines formed by ink-jet printed conductors on flexible Kapton substrates at frequencies up to 60 GHz. It is shown that the lines have losses of approximately 1.5 dB/mm but that this relatively high loss is predominantly due to the loss tangent of the substrates and not the lower conductivity of the silver inks used in this implementation. On an Alumina...
A reconfigurable THz Yagi antenna based on hybrid model combining graphene and metal is proposed. Based on this hybrid model, we designed a Yagi antenna whose radiation pattern can be reconfigured by changing the applied voltage on the parasite graphene elements.
Modifications to a 3D electrically small antenna (ESA) are presented for dual-band and wide-band performance respectively. The design is based on a recently published dome antenna with conformal meanderlines and fed by a microstrip network. By modifying both the meanderlines and microstrips, the antenna is shown to have a voltage standing wave ratio (VSWR) below 3 for the primary 2.45 GHz band and...
Orbital angular momentum radio has great potential for radio communications that require high security, spectrum efficiency and a large data rate. However, the performance of such a system, measured in terms of mode errors, is highly dependent on the alignment between the centre of the receiver array and the transmit array boresight. In addition, other impairment phenomena, such as transmit array...
In this paper, a low-profile on-body antenna is presented for wireless body area network (WBAN) use in 2.45 GHz frequency band. A new design philosophy, where the shape of the antenna structure forms the outer dimensions of the device and enables embedded electronics inside the antenna, is applied in the design. The antenna structure is optimized for vertical polarization and omnidirectional radiation...
A contrast-enhanced microwave radar imaging method using a novel flowing system setup is proposed in this paper. The contrast in electrical properties between dense breast tissues and malignant tissues is low. Therefore, tumour detection using microwaves can be a particularly challenging task. To overcome this problem, we are investigating a radar imaging technique based on a localized contrast enhancement...
A WLAN antenna shaped around a 3D printed bracelet and tested on another printed phantom is proposed. The antenna is a planar dipole with three resonant elements at each end. Inexpensive fuse filament fabrication (FFF) of polylactic acid plastic (PLA) material has been employed for the manufacturing of the bracelet, and the phantom. The phantom was fabricated as a hollow structure which was filled...
We present a meander-line monopole antenna produced by thermal-transfer metallic printing onto a polyester substrate. The antenna is immediately useful because no curing is required. The antenna has a measured fractional bandwidth of 26% centred at 864MHz and directivity of 4.3. The measured and simulated s11 parameter agree well. We show the radiation pattern measured in a near-field spherical scanning...
This paper describes the properties of twin arm wire helical antennas with a balanced feed. Included types are the cylindrical helical, the prolate spherical, the true spherical, the oblate spherical and the twin parallel spiral antenna. Examples for operation at 2.45 GHz for on-body antenna for a body area network are considered. Optimisation of cores with high permittivities was carried out using...
In this paper we implement the idea of fractal geometry in a metamaterial structure, a two-dimensional metamaterial formed by an array of parallel metallic cylinders — the wire medium (WM). This metamaterial has a stop-band at frequencies below an effective plasma frequency which is determined by the radius of the cylinders and the structural period. In contrast to the standard periodic WM, now we...
This paper presents an initial study of reconfigurable antennas made of graphene for multi-band wireless communications applications. A simple microstrip patch antenna with graphene extensions on its sides has been analysed for Wireless Fidelity (WIFI) operational bands, and another microstrip patch antenna with inset notches filled with graphene strips has been evaluated for Long Term Evolution (LTE)...
Site-specific millimeter-wave propagation prediction requires data of the environment under study, which is usually not available for indoor scenarios. With means of laser scanning the details of the indoor environment can be captured accurately in the form of a point cloud. The total field is estimated as a sum of paths backscattering from the point cloud, where the electromagnetic scattering for...
This paper presents the energy efficiency gains derived from the use of a distributed antenna system (DAS) in both hotspot and uniform user distribution scenarios. Results show that when remote radio heads (RRH) are placed according to known hotspot locations, energy reduction gains of 12% are observed and −5% in the case of uniform user distribution. DAS deployment planning based on capacity enhancement...
In this paper, a study is conducted into using an auxiliary ring to enhance the captured (confined) electric field at the gap of dipole nanoantenna for the use in solar rectennas. The system is constructed of main resonator, the dipole antenna, and a booster resonator, the auxiliary ring. It is generally accepted that the dipole antenna captures limited amount of solar radiation. Thus, boosting its...
In the past fifty years it has been clearly identified that the presence of biological tissues effect the performance of the antenna and considerable effort has been made to improve the characteristics of the mobile phone antenna's but very less effort has been put in to evaluate the effects of the radio frequency and energy absorption by the biological organisms and their effect. In this work as...
Civil aviation is considering the use of wireless transmission technology for safety-related on-board machine-to-machine communications. The crucial factor is the availability of a globally harmonized radio frequency band with predictable characteristics in terms of signal propagation and interference induced by other users of that frequency band. Currently the International Telecommunication Union...
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