Antennas

Balanis, C.A.; Polycarpou, Anastasis C.

doi:10.1002/0471219282.eot124

Cited by 71 publications

(88 citation statements)

References 7 publications

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“…The output from the full wave FDTD model in a lossless medium Figure 3 (a) shows that the total power radiated outwardly measured from a cubic surface is conserved: the simulation result of the time average power radiation over one period (

λ = \frac{2 π}{β}

where

β = ω \sqrt{μ ε}

for a lossless medium) minimally changes with propagation (less than 1% difference from the normalized value), which agrees with the energy conservation law [53]. …”

Section: Methodsmentioning

confidence: 79%

Studies in RF Power Communication, SAR, and Temperature Elevation in Wireless Implantable Neural Interfaces

et al. 2013

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Implantable neural interfaces are designed to provide a high spatial and temporal precision control signal implementing high degree of freedom real-time prosthetic systems. The development of a Radio Frequency (RF) wireless neural interface has the potential to expand the number of applications as well as extend the robustness and longevity compared to wired neural interfaces. However, it is well known that RF signal is absorbed by the body and can result in tissue heating. In this work, numerical studies with analytical validations are performed to provide an assessment of power, heating and specific absorption rate (SAR) associated with the wireless RF transmitting within the human head. The receiving antenna on the neural interface is designed with different geometries and modeled at a range of implanted depths within the brain in order to estimate the maximum receiving power without violating SAR and tissue temperature elevation safety regulations. Based on the size of the designed antenna, sets of frequencies between 1 GHz to 4 GHz have been investigated. As expected the simulations demonstrate that longer receiving antennas (dipole) and lower working frequencies result in greater power availability prior to violating SAR regulations. For a 15 mm dipole antenna operating at 1.24 GHz on the surface of the brain, 730 uW of power could be harvested at the Federal Communications Commission (FCC) SAR violation limit. At approximately 5 cm inside the head, this same antenna would receive 190 uW of power prior to violating SAR regulations. Finally, the 3-D bio-heat simulation results show that for all evaluated antennas and frequency combinations we reach FCC SAR limits well before 1 °C. It is clear that powering neural interfaces via RF is possible, but ultra-low power circuit designs combined with advanced simulation will be required to develop a functional antenna that meets all system requirements.

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λ = \frac{2 π}{β}

where

β = ω \sqrt{μ ε}

for a lossless medium) minimally changes with propagation (less than 1% difference from the normalized value), which agrees with the energy conservation law [53]. …”

Section: Methodsmentioning

confidence: 79%

Studies in RF Power Communication, SAR, and Temperature Elevation in Wireless Implantable Neural Interfaces

et al. 2013

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“…1. The array consists of two antenna patches, modelled to have fundamental resonant frequencies at 2.4 GHz and 5.8 GHz by using the design equations given in [4]. The two patches are joined to 50 Ω transmission lines via quarter-wave transformers.…”

Section: Design Of Antenna Array Filters and Their Integrationmentioning

confidence: 99%

Dual-band WLAN Antenna Array with Integrated Filters for Harmonic Suppression

Ahmad¹,

Budimir²

2014

2nd IET Annual Active and Passive RF Devices Seminar

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Abstract:This paper presents the design, modelling and results of a dual-band antenna array integrated with filters. The array is fed via a single 50 Ω port and consists of two radiating elements. Hence, a 1x2 array structure. The two bands of the antenna array correspond to the two WLAN bands of 2.4 GHz and 5.8 GHz. Other than the two fundamental resonant frequencies, the standalone array has spurious harmonics at various other frequencies. For the suppression of these harmonics, the array is integrated with two bandpass filters, centered at 2.4 GHz and 5.8 GHz. The antenna array with integrated filters was electromagnetically modelled and the simulation results have been presented. The acquired results are considerably acceptable; showing the array to have dual-bands at 2.4 GHz and 5.8 GHz, at a return loss of more than 20 dB, and also successful suppression of the spurious harmonics of the antenna array.

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“…We can see that dipole and loop antennas would be larger than the standard monopole antenna supplied with the MicaZ and therefore likely to be an even greater concern for industrial use. Smaller sizes are possible for loops and dipoles, but they do not make effective radiators [7,8].…”

Section: Antenna Requirementsmentioning

confidence: 99%

Improving the Energy Efficiency of Wireless Sensors through Smart Antenna Design

Mason

Shaw

Al-Shamma’a

2011

Lecture Notes in Electrical Engineering

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There is a growing trend in the use of intelligent Wireless Sensor Networks (WSNs) for a wide range of applications. In the early part of the decade the underlying hardware was largely in prototype form and used for small scale demonstration systems, but there is now growing interest in applications which are commercially viable. This work began on the premise that the sensor hardware has gradually become smaller, yet there are still a few peripheral components which are lagging behind; namely the battery and antenna. Here, a novel antenna design is presented; this antenna is of a practical size for use in WSNs, whilst also offering improved energy consumption over commonly used monopole antennas.

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Antennas

Cited by 71 publications

References 7 publications

Studies in RF Power Communication, SAR, and Temperature Elevation in Wireless Implantable Neural Interfaces

Studies in RF Power Communication, SAR, and Temperature Elevation in Wireless Implantable Neural Interfaces

Dual-band WLAN Antenna Array with Integrated Filters for Harmonic Suppression

Improving the Energy Efficiency of Wireless Sensors through Smart Antenna Design

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