Comments on “Theoretical Modeling of a Photoconductive Antenna in a Terahertz Pulsed System”
TL;DR: Amar Nath Yadav and Ratnajit Bhattacharjee as discussed by the authors proposed a matched feed design employing TE 01 and TM 11 modes in a smooth walled rectangular waveguide for cross-polar reduction in offset reflector antenna systems.
Abstract: 1. Amar Nath Yadav and Ratnajit Bhattacharjee, \"Coupled line based unequal dual band power divider\" Accepted for publication in Microwave and Optical Technology Letters. Derivation of potential Green functions for ungrounded dielectric slab and its application in full wave analysis of PMAs, \" accepted for publication in Journal of Electromagnetic Waves and Applications A multipath variant of SCTP with optimized flow division extension \" 8. R. Jana and R. Bhattacharjee, \" Matched feed design employing TE 01 and TM 11 modes in a smooth walled rectangular waveguide for cross-polar reduction in offset reflector antenna systems \" , Average capacity and signal-to-noise ratio analysis of multi-antenna regenerative cooperative relay in Rayleigh fading channel \" , IET
Citations
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TL;DR: In this article, the authors presented an equivalent electrical circuit model of PCA incorporating basic semiconductor device physics, which is validated using Sentaurus TCAD device level modeling tool as well as with the experimental results available in the literature.
Abstract: In recent years, several experimental and simulation studies have been reported on the terahertz (THz) generation using a photoconductive antenna (PCA). The major problem with PCA is its low overall efficiency, which depends on several parameters related to a semiconductor material, an antenna geometry, and characteristics of the laser beam. To analyze the effect of different parameters on PCA efficiency, accurate circuit modeling, using physics undergoing in the device, is necessary. Although a few equivalent circuit models have been proposed in the literature, these models do not adequately capture the semiconductor physics in PCA. This paper presents an equivalent electrical circuit model of PCA incorporating basic semiconductor device physics. The proposed equivalent circuit model is validated using Sentaurus TCAD device level modeling tool as well as with the experimental results available in the literature. The results obtained from the proposed circuit model are in close agreement with the TCAD results as well as available experimental results. The proposed circuit model is expected to contribute towards future research efforts aimed at optimization of the performance of the PCA system.
16 citations
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TL;DR: Graphene-based photoconductive antenna structures for optically excited terahertz (THz) emission was reported in this article. But, the performance of the proposed antenna was not analyzed.
Abstract: Graphene-based photoconductive antenna structures for optically excited terahertz (THz) emission is reported. Initially, a dipole antenna is designed using plasmonic graphene material on GaAs substrate, and its characteristics are found to be better than the previously reported structures. Further, the dipole antenna was improved to a Yagi-Uda-type photoconductive antenna, to obtain a focused radiation pattern. The proposed THz Yagi-Uda antenna is simulated and found to provide a gain of 8.64 dBi and a directivity of 9.57 dBi. Effect of the applied DC bias on the proposed graphene-based dipole and Yagi-Uda photoconductive antennas are also analyzed, and their emission intensities are obtained.
10 citations
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TL;DR: An alternative two-element ECM that accounts for both space-charge and radiation screening effects is presented and validated using the proposed methodology and shows an accurately reproduced THz pulse using a reduced number of circuital elements, which represents an advantage for PCA modeling.
Abstract: Comparison of equivalent circuit models (ECM) for photoconductive antennas (PCA) represents a challenge due to the multiphysics phenomena involved during PCA operation and the absence of a standardized validation methodology. In this work, currently reported ECMs are compared using a unique set of simulation parameters and validation indicators (THz waveform, optical power saturation, and ECM voltages consistency). The ECM simulations are contrasted with measured THz pulses of an H-shaped 20μm gap PCA at different optical powers (20mW to 220mW). In addition, an alternative two-element ECM that accounts for both space-charge and radiation screening effects is presented and validated using the proposed methodology. The model shows an accurately reproduced THz pulse using a reduced number of circuital elements, which represents an advantage for PCA modeling.
7 citations
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TL;DR: In this article, a basic Ti-Au dipole antenna on GaAs substrate is designed initially and it is enhanced into a photoconductive antenna for terahertz emission.
Abstract: Many terahertz applications such as sensing, imaging, and spectroscopy require coherent terahertz (THz) sources. A basic Ti-Au dipole antenna on GaAs substrate is designed initially and it is enhanced into a photoconductive antenna for terahertz emission. A spectral width of 120 GHz is obtained from the emission spectrum. In order to compare the spectral characteristics, a graphene dipole antenna is designed on the same substrate. It is observed that graphene dipole yields a narrower spectral width of 70 GHz, due to its high Q factor. Spectral width of the graphene dipole antenna is further made narrow to 25 GHz, by incorporating a λ/4 stub on the stripline to produce a filtering operation. The antenna provides a directivity of 6.14 dBi with stub which shows an improvement of 0.3 dB when compared with an antenna without stub.
5 citations
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TL;DR: Prajapti et al. as discussed by the authors presented a reply to comments made on the paper, "Theoretical modeling of a photoconductive antenna in a Terahertz Pulsed System" (PRAJapti, J., et al), IEEE Trans. Antennas Propag., vol. 64, no. 6, pp. 2583-2584, 2016.
Abstract: Presents a reply to comments made on the paper, "Theoretical modeling of a photoconductive antenna in a Terahertz Pulsed System" (Prajapti, J., et al), IEEE Trans. Antennas Propag., vol. 64, no. 6, pp. 2583–2584, 2016.
2 citations
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References
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TL;DR: In this paper, a novel equivalent circuit model using lumped elements is developed for analyzing the performance of these antennas, whilst keeping the simplicity of the lumped element approach, the underlying physical behavior of the device is taken into account when calculating the circuit elements.
Abstract: The most common device for terahertz (THz) wave generation and detection is a THz photoconductive antenna. This paper examines the factors which affect the radiated power and optical-to-THz power conversion efficiency of the antenna. A novel equivalent circuit model using lumped elements is developed for analyzing the performance of these antennas. In this model, whilst keeping the simplicity of the lumped element approach, the underlying physical behavior of the device is taken into account when calculating the circuit elements. Based on the model, the influence of various parameters on the optical-to-THz power conversion efficiency and radiated power is then investigated. The simulated results agree well with published measured results. The model predicts that an increase in the laser power and/or bias voltage, and a reduction in reflections from the air-substrate can improve the optical-to-THz power conversion efficiency of the device. This novel model is very useful for both designing a THz antenna and tuning a THz system to achieve maximized optical-to-THz power conversion efficiency and THz radiated power.
96 citations
"Comments on “Theoretical Modeling o..." refers background or methods in this paper
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TL;DR: Performance of cooperative relaying employing infrastructure based fixed relays having multiple antennas has been investigated, employing MGF based approach, closed form expression for outage probability and bit error rate performance of BPSK signal have been derived.
Abstract: Performance of cooperative relaying employing infrastructure based fixed relays having multiple antennas has been investigated. Employing MGF based approach, closed form expression for outage probability and bit error rate performance of BPSK signal have been derived, when relay and destination are assumed to perform MRC combining of the signals. The effect of relay placement on the system performance has also been studied under different path loss conditions.
35 citations
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TL;DR: Performance of cooperative relaying employing infrastructure based fixed relaysHaving multiple antennas having multiple antennas has been investigated and both relay and destination perform maximal ratio combining combining of the signals.
Abstract: Performance of cooperative relaying employing infrastructure based fixed relays having multiple antennas has been investigated. Here, both relay and destination perform maximal ratio combining combining of the signals. Closed form expressions for outage probability and bit error rate have been derived for Nakagami-m fading channels, with integer values of m. The effect of fading correlation among relay antennas and relay positioning on the system performance have also been studied.
35 citations
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TL;DR: This letter investigates the performance of an infrastructure based multi-antenna relay network in the absence of a direct link, and derives a closed form expression of outage probability, when the cooperating relays and destination coherently combine the received signals.
Abstract: Cooperation among relays can achieve spatial diversity, which improves the link quality in a wireless network. In this letter, we investigate the performance of an infrastructure based multi-antenna relay network in the absence of a direct link. A closed form expression of outage probability has been derived, when the cooperating relays and destination coherently combine the received signals. The effect of number of relay antennas and relay placement on the system performance have also been studied.
24 citations
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TL;DR: In this article, a geometrical single bounce scattering model has been used to study the mobile-to-mobile communication channel and analytical expressions for angle of arrival and time of arrival probability density functions have been derived for such models.
Abstract: of mobile-to-mobile communication channel have been studied through a geometrical single bounce scattering model and analytical expressions for angle of arrival and time of arrival probability density functions have been derived for such models. Analytical expressions have been verified through computer simulations. This paper aims to provide a better understanding of mobile-to-mobile channel behavior in terms of the parameters studied.
19 citations
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