Rula Alrawashdeh

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.

UWB planar antennas for wireless capsule endoscopy

Wireless capsule endoscopy (WCE) has conquered some limitations of traditional diagnosing tools, such as the comfortlessness of the cables and the inability of examining small intestine section. However, this technique is still far from satisfactory and requires some feasible improvements. Antennas play a major role in achieving these improvements and in building up the communication link between the capsule and the external receiver. Therefore, the design of a WCE transmitter antenna has been investigated in this paper. Two planar antennas are proposed and optimized in this paper. These two planar antennas have an ultrawide bandwidth, omnidirectional radiation pattern and deep return loss, which can meet the requirements for WCE system.

A flexible loop antenna for total knee replacement implants in the MedRadio band

In this paper a new flexible loop antenna is proposed for total knee replacement implant applications. Because of its flexibility this antenna can be bent around the outer wall of the implantable sensor which has a cylindrical shape providing conformity and leaving more space for other internal components such as batteries. Considering a very realistic model of an adult leg, the antenna has shown a very good performance covering the entire medical radio communication service (MedRadio (401-406 MHz)) band with an omnidirectional radiation pattern, and having much higher radiation efficiency and realized gain than most of reported implantable antennas. The effect of the size and structure of the implant on the performance of the antenna has been investigated and shown for the purposes of influencing actual designs of implantable antennas.

Broadband U-shaped water antenna for DVB-H applications

In this paper, a low profile, broadband, dielectric resonant antenna (DRA) with a U-shaped water layer is presented for DVB-H (470 - 862 MHz) mobile applications. The U-shaped water layer is used as a radiator to reduce the antenna size. The proposed antenna has a -6 dB impedance bandwidth from 461 to 1019 MHz, or a fractional bandwidth of 75%, and about 1.5 dBi gain covering the whole DVB-H band. The computer simulation is conducted to quantify and validate the antenna performance. It is demonstrated that this novel antenna is an excellent candidate for DVB-H applications.

Orientation effect of flexible implantable antennas on performance

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.

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

A novel antenna design for implantable pacemakers is proposed. The housing of a pacemaker is utilized as an antenna to cover both the 402-405 MHz Medical Implant Communication Service band and the 433-MHz Industrial, Scientific and Medical band. This is achieved by exploiting radiating characteristic current modes of the housing case. These modes are excited using a capacitive coupling element with the help of a matching circuit. The radiation pattern of this antenna is optimized to be in a desirable direction away from the body (off-body direction). The ability of the proposed antenna for communications is demonstrated using a transceiver and a base station at 433 MHz. A communication range of 1 m is established when a transmitter with the proposed antenna is implanted in a rabbit and the power fed by the transceiver to the antenna is 25 μW. A longer range of up to 19 m can be established with the maximum allowable transmit power within the safety limits. Furthermore, the far field wireless power transfer through the proposed antenna is investigated by experiment. A received power of up to 22.38 μW by the proposed antenna is demonstrated when an equivalent isotropically radiated power of 140 mW is transmitted 1 m away from a transmitting antenna. From the same transmitting antenna in the same distance, a power of 4 mW can be received when the transmit power is within safety limits. This power can be used to recharge a small battery or a capacitor, which can potentially cover the communication power consumption of the pacemaker and hence extend the life span of the primary battery.

A dual broadband butterfly loop antenna for body wearable applications

A dual broadband flexible butterfly loop antenna is designed to be worn on a human body which covers several important bands for wearable applications including the MedRadio band 402-406 MHz and ISM bands (433-434, 902-928 and 2400-2483.5) MHz. This antenna offers two wide bands for the reflection coefficient S11 -10 dB from 430-1003 MHz and 2004-2700 MHz with bandwidths of 573 and 696 MHz respectively. The MedRadio band is covered with S11 under -6 dB. This feature gives the antenna robustness against the frequency detuning effects of the body and makes it suitable for in-body services such as communication and wireless power transfer.

A comparison of the effect of substrate on the performance of THz antenna

THz photoconductive material is one of the intensely studied topics in the THz field. The effect of substrate thickness on the radiated THz power had been studied by various researchers. In this paper also, THz antenna performances using different substrate material are compared and discussed. It has been shown that the thinner substrate used and the higher the electron mobility of the substrate, the higher THz radiated power produced.