Muayad Kod

A Broadband Flexible Implantable Loop Antenna With Complementary Split Ring Resonators

In this letter, a novel flexible implantable loop antenna with complementary split ring resonators (CSRRs) is proposed and designed for biomedical telemetric applications. The antenna has a very wide bandwidth to cover the Medical Device Radiocommunications service (MedRadio 401-406 MHz) and Industrial, Scientific and Medical (ISM 433.1-434.8, 868.0-868.8, 902.8-928.0 MHz and 2.45 GHz) bands which support the functions of wireless data transmission, wireless power transfer and saving (wakeup receiver). It is optimized over a two-step design process for cylindrical implants for a robust communication over 2 m. The CSRRs are introduced to reduce the absorbed power inside the body and improve the antenna impedance matching. This results in a larger radiation efficiency, gain and transmission coefficient (over 2 dB in comparison with the structure without the CSRRs). The specific absorption rate (SAR) is also decreased significantly. Measurements in a pork phantom are conducted and a good agreement with the simulation results is demonstrated. This novel antenna could be an excellent candidate for a range of implantable applications.

Reconfigurable 3D folded monopole antenna design for DVB-H applications

A frequency tunable compact 3D folded monopole antenna designed for DVB-H applications is presented. By loading the folded monopole antenna with a variable capacitor, the operating frequency of the antenna can be continuously tuned over the frequency range of the DVB-H standard, from 470 MHz to 862 MHz. Furthermore, a water layer is loaded to reduce the dimensions of the antenna while keeping a reasonable bandwidth for DVB-H specifications. The antenna element occupies a very small volume 17.5 mm × 7 mm × 3 mm (probably the smallest reported volume for DVB-H applications), thus it is a very promising candidate for DVB-H applications.

A Miniaturized Low-Profile Multilayer Frequency-Selective Surface Insensitive to Surrounding Dielectric Materials

In most applications, a frequency-selective surface (FSS) needs to be attached to a wide variety of dielectric materials. The performance of a traditional FSS is greatly influenced by the dielectric material to which it is attached. In this paper, a novel multilayer structure is proposed to construct an FSS. The performance of the proposed structure is shown to be very stable when it is attached directly to a wide variety of dielectric materials of arbitrary thickness. Both single- and dual-polarized structures are designed. The shape of the FSS element is designed by using stepped-impedance transmission lines. A new methodology is proposed to design the FSS by maximizing the value of the capacitance between adjacent layers. The proposed structure offers three distinctive advantages. First, the strong cross-layer capacitance makes the FSS element very compact. The dimensions of the miniaturized element are as small as

Frequency Selective Surface Structure Miniaturization Using Interconnected Array Elements on Orthogonal Layers

0.012 \lambda \times 0.012 \lambda

Label-type 3D RFID tag mountable on metallic and non-metallic objects

. Second, for the proposed structure, the lower the profile, the stronger the cross-layer capacitance, and the lower the resonant frequency. This is unique to the proposed structure since the resonant frequency is usually higher for a lower profile for traditional structures. Third and most importantly, any external dielectric material attached to the FSS will not significantly affect the performance of the FSS due to this strong cross-layer capacitance. Through examples of a single-polarized bandpass FSS at 1 GHz and a dual-polarized bandpass FSS at 1.96 GHz, it is demonstrated that a stable resonant frequency under various incident angles up to 75° can be achieved.

Orientation effect of flexible implantable antennas on performance

Traditionally, the element of a frequency selective surface (FSS) is rotationally symmetrical and the element arrays in a multilayer FSS are aligned with each other. A new approach to miniaturize the size of the FSS array element is proposed in this paper by interconnecting the array elements only in one direction in a two-layer FSS structure. One layer acts as an enhanced inductor while the other layer provides capacitance. The interconnection between the adjacent array elements changes the equivalent circuit and produces a strong cross-layer capacitance, which lowers the resonant frequency significantly. The dimensions of the miniaturized FSS element are much smaller than the wavelength at the resonant frequency (periodicity

A UHF RFID Tag With Improved Performance on Liquid Bottles

\ll \lambda )

Feasibility Study of Using the Housing Cases of Implantable Devices as Antennas

. The element can also have a low profile since the cross-layer capacitance is stronger with a thinner substrate. The sensitivity to the incident angle of the proposed structure is comparable with traditional ones. A theoretical equivalent circuit model is developed to characterize the structure, based on the analysis of the geometrical configuration of the FSS structure and the electric field distribution on it. The theory was verified by the experimental results.

A dual broadband butterfly loop antenna for body wearable applications

A study for reducing the sensitivity of label-type UHF RFID tags to background materials is done in this paper. It is found that the capacitance in parallel to the feeding point of the tag is the most sensitive element in the circuit. The capacitance of the antenna body is also found to be an important element. The bigger antenna capacitance leads to less sensitive tag designs. Based on these findings a low profile and low cost label-type tag design is proposed. The feeding point is protected by a bottom conducting layer in a 3D design and the dipole antenna is loaded with large capacitive patches at both tips. The tag not only shows acceptable reading range on various dielectric materials but also is capable of working on challenging materials like liquid bottles and metallic objects.

Frequency selective surface with simple configuration stepped-impedance elements

In this paper, the effect of the orientation of implantable antennas on their performance inside the body model is studied. The reflection coefficient, gain, radiation efficiency and SAR values are investigated for three different antenna orientations in an asymmetric anatomical body model. It is found that the antenna performance is closely linked to the orientation of the antenna even for the same position inside the body. The analysis in this paper provides a valuable insight into the accurate evaluation of implantable antennas.