Smanjenje sprege između dviju planarnih obrnutih-F antena s područjem rada u bliskim frekvencijskim pojasima

This paper presents a solution to reduce the mutual coupling between two Planar Inverted-F Antennas (PIFAs) working in close frequency bands: DCS1800 (1710-1880 MHz) and UMTS (1920-2170 MHz). The antennas are positioned on the top corner of a ground plane whose size is representative of the Printed Circuit Board (PCB) of a typical mobile phone. Two antenna-systems are designed and several arrangements are studied, especially when suspended line is inserted between the radiators. This line is intended to act as a neutralization device and then reduce the mutual coupling. Several prototypes are fabricated and measured to validate the proposed solution.U radu je predstavljeno rješenje smanjenja sprege dviju planarnih obrnutih-F antena (PIFA) s područjem rada u bliskim frekvencijskim pojasima: DCS1800 (1710–1880 MHz) i UMTS (1920–2170 MHz). Antene su postavljene u vrh uzemljene ravnine čija je veličina predstavnik tiskanih pločica (PCB) tipičnih mobilnih telefonskih uređaja. Tri antene su konstruirane i nekoliko modifikacija je proučavano, posebice u vezi postavljanja neaktivne prijenosne linije između njih. Ta prijenosna linija je zamišljena da služi kao neutralizirajuća komponenta i da stoga smanjuje međusobnu spregu. Nekoliko prototipova je izvedeno i izmjereno u cilju verifikacije predloženog rješenja

Broad-band embroidered spiral antenna for off-body communications

An embroidered wearable spiral antenna is presented in this study. The spiral antenna is compact and flexible, yet has broad-band performance. The novelty of this study includes considering the antenna–body interaction rather than just considering the antenna alone. The antenna has been simulated and measured on a specific anthropomorphic mannequin torso phantom and a real person. The far-field on-body performance of the embroidered antenna on the phantom has been measured using a novel cylindrical near-field to far-field transformation technique. This technique allows the fast extraction of the full spherical radiation pattern and the corresponding far-field antenna characteristics on the human body without the need of rotating the phantom with expensive positioning systems. The on-body antenna performance including realised gain, directivity, radiation efficiency, radiation pattern and axial ratio have been presented

Ultra-broadband antenna with robustness to body detuning for 4G eyewear devices

An ultra-broadband antenna design for 4G cellular coverage in eyewear devices is presented in this paper. The antenna has been designed considering a realistic eyewear PCB and its dielectric frame. In order to overcome any negative effects from the antenna's surroundings (frequency detuning due to the head and the hand of the user), the antenna was designed to cover continuously the 700-2700 MHz band with a reflection coefficient below -6 dB instead of a dual-band behavior usually required for 4G operation: 700-960 MHz and 1700-2700 MHz. The antenna was of capacitive coupling element type with its appropriate matching network to cover the mentioned frequency interval. To emulate a realistic device, an ABS plastic dielectric frame was manufactured using 3D-printing technology. The antenna was simulated and tested in three different use-cases as: "default case with user's head", "with head and hand" and "free space" cases. State-of-the art performance is demonstrated. The specific absorption rate (SAR) behavior was also investigated through simulations and measurements to check the compliance with regulations

4G antennas for wireless eyewear devices and related SAR

In this paper, we first present a feasibility study to design 4G antennas (700–960 MHz and 1.7–2.7 GHz) for eyewear devices. Those eyewear devices should be connected to the last generation cellular networks, Wireless Local Area Networks or wireless hotspots. Three coupling element type antennas with their matching networks are evaluated in terms of reflection coefficient and total radiation efficiency when the eyewear is placed on the user's head. We also present Specific Absorption Rate (SAR) simulations when the eyewear is positioned over a homogeneous SAM phantom and over a heterogeneous VH (Visible Human) phantom: the SAR levels are compared to international limit values. In a second step, we present experimental results obtained with 3D printed eyewear and coupling elements etched on a classical PCB substrate where the matching circuits are optimized close to the feeding point of the coupling element. Simulated and measured values are in very good agreement: 7 to 16% and 9 to 35% total efficiency are respectively obtained for the low- and high-frequency bands. However, simulated SAR values are somewhat higher than authorized levels with preoccupant high electromagnetic field distribution close to the eye of the user

Investigation of the effect of metallic frames on 4G eyewear antennas

In this paper, we investigate the effect of metallic eyewear frames on the reflection coefficient, the radiation pattern and the specific absorption rate (SAR) of 4G antennas integrated in eyewear. The antennas used in the study are Coupling Element type, with appropriate matching networks to cover simultaneously the 700-960MHz and 1.7-2.7GHz frequency bands. Two different antenna locations are evaluated: behind the user's ear and at the opposite corner of the printed circuit board, close to the eye. For both antennas, the effect of metallic frames is investigated through numerous simulations. Compared to the case without metallic frame, the matching and radiation patterns are slightly affected. Although there is a redistribution of the SAR hotspots inside the head, the change in the 1g and 10g SAR values are marginal as a result of including the metallic frame

Dual-band 4G eyewear antenna and SAR implications

This paper presents low-cost and easy-to-manufacture dual-band antenna solution to achieve cellular 4G (LTE-Advanced) coverage in smart eyewear devices. Coupling element type antenna has been evaluated with appropriate matching networks to cover the target bands of 700-960MHz and 1.7-2.7GHz. To emulate a realistic device, an ABS plastic dielectric frame has been designed and manufactured using 3D printing technology. Simulations for the antenna are carried out in three typical use-case scenarios which are "with user's head", "with head and hand" and "free space". The simulations are validated through S-parameters, efficiency and radiation pattern measurements using fabricated frame and antenna prototype in the presence of head and hand phantoms. The SAR behavior of the antenna designs is also investigated through simulations and measurements. It is demonstrated that SAR values are found to be above the limitations which might be problematic in practical use if the transmit power of the eyewear is not reduced

Feasibility study of 4G cellular antennas for eyewear communicating devices

A feasibility study of 4G cellular antennas operating in the LTE, GSM, DCS, PCS, and WLAN2400 standards for wirelessly connected eyewear is presented. The target bands are 700-960 MHz and 1.7-2.7 GHz. The antenna designs are capacitive coupling element types, with simple layout printed on one side of the printed circuit board (PCB) substrate. Three different antennas are examined in terms of obtainable bandwidth potential, reflection coefficient, and specific absorption rate (SAR) values considering two human-head models (SAM and Visible Human). The best antenna is -6 dB matched and has radiation efficiencies around 14% and 36% in respectively low and high frequency bands. Based on simulation data, SAR values could be above the 1-g standards

Feasibility study of 4G cellular antennas for eyewear communicating devices

A feasibility study of 4G cellular antennas operating in the LTE, GSM, DCS, PCS, and WLAN2400 standards for wirelessly connected eyewear is presented. The target bands are 700-960 MHz and 1.7-2.7 GHz. The antenna designs are capacitive coupling element types, with simple layout printed on one side of the printed circuit board (PCB) substrate. Three different antennas are examined in terms of obtainable bandwidth potential, reflection coefficient, and specific absorption rate (SAR) values considering two human-head models (SAM and Visible Human). The best antenna is -6 dB matched and has radiation efficiencies around 14% and 36% in respectively low and high frequency bands. Based on simulation data, SAR values could be above the 1-g standards

MIMO antenna concept for 4G electronic eyewear devices

MIMO antenna concepts for electronic eyewear devices operating in 4G cellular standard are proposed in this paper. Coupling element type antennas and matching circuits are used to obtain a high bandwidth potential for the coverage of the 700-960MHz and 1.7-2.7GHz frequency bands. To obtain a dual-antenna MIMO configuration, two CE type antennas are placed on the two sides of the head, resulting in a very high isolation level thanks to the lossy nature of the human tissues (head). It is shown through simulated 3D radiation patterns that very low envelope correlation coefficients are obtained for this placement. Preliminary SAR simulations show values above the 1g standards