International Journal of Innovative Research in Electrical, Electronics, Instrumentation and Control EngineeringA monthly Peer-reviewed & Refereed journal
IJIREEICE meets the suggestive parameters outlined in the latest University Grants Commission (UGC) for peer-reviewed journals, ensuring high standards of research integrity, publication ethics, and academic excellence.
Power quality improvement with a shunt active power filters using MATLAB Simulink
D.SANDEEP KUMAR, G.VENU MADHAV
DOI: 10.17148/IJIREEICE.2015.3101
Abstract: Along with the increasing demand on improving power quality i.e generally defined as any change in power (voltage, current, or frequency) that interferes with the normal operation of electrical equipment, the most popular technique that has been used is Active Power Filter (APF); This is because Passive filters performance is limited to a few harmonics and they can introduce resonance in the power system. Passive filters are larger component sizes and therefore Costs high. So APF can easily eliminate unwanted harmonics, improve power factor and overcome voltage sags and eliminate any harmonic frequencies. This paper will discuss and analyze the simulation result for a three-phase three wire shunt active power filter using MATLAB program. This simulation will implement a non-linear load, to compensate line current harmonics under balanced and unbalance loads. As a result of the simulation, it is found that an active power filter is the better way to reduce the total harmonic distortion (THD)
Keywords: APF, PWM converter, d-q theorm, THD, Power Quality, Instantaneous Power theory
Abstract: Global warming is one of the most important issues facing humanity. The depth and extent of sea-ice are clear indicators of global warming. Snow cover on sea-ice is an important variable that affects the volume of sea-ice and indirectly global warming as a whole. This paper discusses the design of snow radar. Various models in the design of the snow radar are discussed. It concludes with the problems and the solutions to rectify the issues.
Keywords: FM-CW, RADAR, beat frequency, back ray scattering principle.
Ultra wideband antenna for high data rate applications
MONAGOYAL, DR. BALRAJ SINGH SIDHU
DOI: 10.17148/IJIREEICE.2015.3103
Abstract: In this paper, a pentagon shaped ultra-wideband (UWB) antenna is proposed and developed for wireless communication systems. This antenna has low profile, light weight and has successfully demonstrated multiband and broadband characteristics. The simulated results show that proposed antenna has very good performance in impedance bandwidth and radiation pattern. A better impedance bandwidth is obtained from 3.1 GHz to 13.48 GHz that constitutes a fractional bandwidth of 125 % with return loss less than or equal to -10 dB (VSWR < 2). The comparative results reveal that the proposed antenna possesses wider bandwidth than the earlier published structure. This designed antenna can be used for any wireless UWB device for high data rate applications.
Vessel extraction from retinal images by using matched filter and first derivative of Gaussian function
S.J. DESHMUKH, S.B.PATIL
DOI: 10.17148/IJIREEICE.2015.3104
Abstract: Accurate detection of blood vessels from retina is an important job in computer aided diagnosis of Diabetic Retinopathy. The Matched filter is simple & effectively good method for vessel extraction. But Problem with that it recognizes vessels and non-vessels edges so it will detect false vessels. In this paper we introduce new extension of Matched Filter i.e. FDOG to extract the vessels. The MF-FDOG is combination of Matched filter which is zero mean Gaussian Function and First order derivative of Gaussian. The vessels are detected by thresholding the response of Matched Filter and Threshold is adjusted by image response of FDOG. The proposed method is very simple and it reduces false detection of Matched filter and detects all fine vessels which are not detected by matched filter. It gives good competitive results of vessel detection with low complexity.
Keyword: Diabetic Retinopathy (DR), Matched filter (MF), First order derivative of Gaussian Function (FDOG).
A robust speed sensorless vector control of multilevel inverter fed induction motor using particle swarm optimization
SANYAJA KUMAR SAHU, D.D.NEEMA
DOI: 10.17148/IJIREEICE.2015.3105
Abstract: A novel speed sensor less adaptive robust control method is proposed to improve the trajectory tracking performance of induction motors. The proposed design employs the so called vector control (or field oriented control) theory for the multilevel inverter fed induction motor drives. The inverter design is based on three- level Neutral Point Clamped (NPC) inverter with hysteresis current control technique. Two Mamdani type fuzzy logic controllers are used; one as speed controller and the other is in Luenberger Observer in order to estimate the actual rotor speed. The Particle Swarm Optimization algorithm is used to optimize the parameters such as membership functions, normalizing and de- normalizing parameters of fuzzy logic controller. The performance of proposed scheme is investigated under various load and speed conditions. The simulation results show its stability and robustness for high performance sensor less drive applications.
Keywords: Field Oriented Control (FOC), Multilevel Inverter, Hysteresis Current Control, Particle Swarm Optimization (PSO), Fuzzy Logic Controller.
Comparative study on a low drop-out voltage regulator
SHIRISH V. PATTALWAR, ANJALI V. NIMKAR
DOI: 10.17148/IJIREEICE.2015.3106
Abstract: Today’s LDO (low drop-out voltage regulator) must meet the requirements of various future demands of the portable electronics. To get a new approach towards a design of low drop-out voltage regulator that provides a modern system on chip (SoC) solution and fulfils the present commercial requirements as well as the projected demands of the future, it becomes necessary to study the literature work. The various performance matrices such as minimization of drop-out voltage, low power, low operating voltages, low quiescent currents, fast transient response, high PSR and high packing density have a vital importance in designing of LDO regulator. Furthermore, capacitor less LDO architecture, overcomes the typical load transient and ac stability issues. The designing can be possible with Digital implementation and programmability can be added to become suitable for more applications. Considering the advancement of future technology, regulator can be proposed with the selection of lower order of nm technology. This paper presents the comparative study of literature work that contributes to the research of LDO using CMOS technology and provides different architectures and techniques to make LDO better.
Comparison of two different approaches for multiple face detection in color images
NEETU SAINI, HARI SINGH
DOI: 10.17148/IJIREEICE.2015.3107
Abstract: Human face detection has become a major field of interest in current research because there is no deterministic algorithm to find multiple faces in a given image. In this paper, the performance comparison has been made of two different algorithms for multiple face detection in color images. First algorithm combines HSI and YCbCr color models along with morphological operations. In the second algorithm, RGB color model with Viola-Jones algorithm is used. After making comparison, it is found that; first algorithm gives better detection accuracy (91%) as compared to the second method (88%). But, first algorithm requires more processing time which is matter of concerned in real-time face detection. The average processing time required for first algorithm is about 6.3sec, whereas for second algorithm it is 5.1sec.
Keywords: Color models, Multiple Face Detection, Morphological Operations, Viola Jones
Abstract: The importance of cryptography applied to security in electronic data transactions has acquired an essential relevance during the last few years. A proposed FPGA-based implementation of the Advanced Encryption Standard (AES) algorithm is presented in this paper. The design has been coded by Very high speed integrated circuit Hardware Descriptive Language. All the results are synthesized and simulated using Xilinx ISE and ModelSim software respectively. This implementation is compared with other works to show the efficiency. The design uses an iterative looping approach with block and key size of 128 bits, lookup table implementation of S-box. This gives low complexity architecture and easily achieves low latency as well as high throughput. Simulation results, performance results are presented and compared with previous reported designs.
Keywords: AES, FPGA, encryption decryption, block cipher and VHDL.
Power system security analysis under transmission line outage condition
S.RAVINDRA, V.C.VEERA REDDY, S.SIVANAGARAJU
DOI: 10.17148/IJIREEICE.2015.3109
Abstract: The power system becomes more severe under contingency conditions. In general, the contingencies may be outage of transmission lines or generators. To identify the effect of outages on system security, the contingency analysis is one of the analytical tools. The congestion on a system must be manages using generation rescheduling and with the proper control of the compensation equipments. The transmission line outage sometime increases the total power system losses, cascading outage of transmission lines, etc. Finally, the system leads to collapse condition. To avoid this type of uncontrolled condition, the power system security needs to be analyzed under transmission line outage condition. In this paper, the most critical transmission lines are identified using line collapse proximity index values and the system severity is analyzed in terms of transmission line loadings, bus voltage magnitude variations are tested on standard IEEE-14 bus test system and the analytical results are presented in numerically and as well as graphically.
Keywords: Power system security, contingency analysis, transmission line outages, line collapse proximity index.
Abstract: The era of entirely wireless, mobile communication is rapidly approaching.Increasingly; users are demanding versatile and convenient modes of communication along with high-speed broadband and technology in the premise of guaranteeing certain quality of communication without losing performance and efficiency. The challenges are to give users high-speed, high-performance in different channel conditions. So, Orthogonal Frequency Division multiplexing (OFDM) has been recognized as one of the most promising techniques to meet these challenges. Space Time block Coding (STBC) has drawn much attention in 4G wireless technologies just because of its decoding simplicity. This paper presents the performance evaluation of STBC-OFDM systems covering channel model and coding scheme, it includes Rayleigh fading channels by which it is observed that Bit Error Rate(BER) is reduced to achieve the high data rate.In this work, a performance criterion such as bit error rates for low SNR is analyzed. The BER for OFDM system over Rician fading channel is observed to be 0.1273.It has been reduced to 0.03919 over Rayleigh fading channel with Line of Sight (LOS) for the same Signal to noise ratio (SNR).
A Review extraction of solar cell modelling parameters
RITURAJ TAMRAKAR, ARCHANA GUPTA
DOI: 10.17148/IJIREEICE.2015.3111
Abstract: Energy from the sun is the best option for electricity generation as it is abundantly available everywhere and sustainable source. Advance of Photovoltaic (PV) technology in recent years has made solar energy one of the practical alternative energy sources available in the energy market. In order to make the PV energy more affordable and cost effective, major focus of the research community and industry is improvement on power efficiency of PV systems. Parameter extraction of solar cell plays a crucial role in the simulation and design calculation of PV system. The circuit model of a solar cell is non-linear and transcendental. Different methods under the categories of analytic, iterative, and evolutionary computational have been proposed to extract the parameters of solar cell in recent years. This paper presents a survey on parameter extraction of solar cell model and its recent advances.
Context aware driver’s behavior detection system using Zigbee Result
PRIYANKA B.SHINDE, VIKRAM A.MANE
DOI: 10.17148/IJIREEICE.2015.3112
Abstract: Dedicated short range Communication to allow vehicles in close proximity to communicate with each other, or to communicate with roadside equipment. Applying wireless access technology in vehicular environments has led to the improvement of road safety and a reduction in number of fatalities caused by road accidents, through the development of road safety applications and facilitating information sharing between moving vehicles regarding the road. This paper focuses on developing a novel and non-intrusive driver behavior detection system using a context aware system in wireless to detect abnormal behaviors exhibited by drivers, and to warn other vehicles on the road so as to prevent accidents from happening. In real time inferring four types of driving behavior (normal, drunk, reckless and fatigue) by combining contextual information about the driver, vehicle and the environment is presented. The evaluation of behavior detection using synthetic data proves the validity of our model and the importance of including contextual information about the driver, the vehicle and the environment.
CCV based image retrieval for FMIQ with confined histogram refinement
SATYAWATI M. PATIL, V.K.PATIL
DOI: 10.17148/IJIREEICE.2015.3113
Abstract: Content Based Visual Information Retrieval is one of the most cardinal and crucial aspect in the category of digital image processing. The significant mechanism that has been lucidly highlighted here is the fast multiresolution image querying using Color Coherence Vector (CCV) along with the refinement of color histogram. However, the retrieval speed and accuracy can be enhanced using color characteristics and mathematical model despite the collection of innumerable images in dataset. Color feature extraction and coherency estimation assist in flawless and swiftest image querying according to the matched template (matrices) of the color histogram image with maximum precision.
Keywords: CCV, color histogram refinement, coherency image querying.
Examining dielectric properties of paper ageing in scrapped transformers
ASMAA BADR, LOAI NASRAT, ABDULLA IBRAHIM
DOI: 10.17148/IJIREEICE.2015.3114
Abstract: Experimental Study of degradation of oil impregnated paper has attracted enormous attention over the past 20 years worldwide. Outside the controlled conditions of the laboratory, however the real situation is more complex due to loading change, ambient temperature, fluctuation and sudden impulse impact. Therefore, interests in forensic examinations of scrapped old transformers have increased in recent years since it may be a way to obtain under-service ageing information and connecting the laboratory ageing experiment with the reality. This paper presents the effect of ageing on the breakdown voltage and examines the effect of oil quality on the breakdown voltage of the paper. Tests results of service-aged papers taken from three failed power transformers. The result indicated that ageing has a small reduction effect on the breakdown voltage, whereas the breakdown voltage is affected more by the density of the paper and the quality of the oil.
A transformerless inverter with virtual dc bus concept for grid-connected PV power systems
T.PARANDHAMAIAH, M.HARINARAYANA, Dr. B.DURGA PRASAD
DOI: 10.17148/IJIREEICE.2015.3115
Abstract: The traditional grid-connected PV inverter includes either a line frequency or a high frequency transformer between the inverter and grid. The transformer provides galvanic isolation between the grid and the PV panels. In order to increase the efficiency, to reduce the size and cost, the effective solution is to remove the isolation transformer. It leads to appearance of common mode (CM) ground leakage current due to parasitic capacitance between the PV panels and the ground. The common mode current reduces the efficiency of power conversion stage, affects the quality of grid current, deteriorate the electric magnetic compatibility and give rise to the safety threats. In order to eliminate the common mode leakage current in transformer less PV system, the concept of virtual DC bus is proposed. By connecting the grid neutral line directly to the negative pole of the DC bus, the stray capacitance between the PV panels and the ground is bypassed. The CM ground leakage current can be suppressed completely. Virtual DC bus is created to provide the negative voltage level for the negative AC grid current generation. The virtual DC bus is realized with the switched capacitor technology that uses less number of elements. Therefore, the power electronic cost can be reduced. This topology can be modulated with the unipolar SPWM to reduce the output current ripple. A smaller filter inductor can be used to reduce the size and magnetic losses. The simulation result of the proposed topology using MATLAB/SIMULINK is analysed in detail, with the results verified by a prototype.
Keywords: Photovoltaic (PV) system, Common mode (CM), Unipolar sinusoidal pulse width modulation (SPWM), Transformerless inverter, Virtual dc bus.
Measure of reflection and transmission coefficients for bone tissues
Y.RATNA KUMAR, PROF. G.S.N.RAJU
DOI: 10.17148/IJIREEICE.2015.3116
Abstract: In this paper we analyzed the behavior of the Electromagnetic waves on some of the human tissues. As Electromagnetic waves propagate from one homogeneous medium to another, they experience a change of the wave impedance in the interface. The impedance mismatch generally leads to the reflection, absorption, and transmission of Electromagnetic waves. In the case of non homogeneous media like a human body, it is complex to analyze the behavior of Electromagnetic waves. The reflection and transmission coefficients vary from tissue to tissue and they are dependent on permittivity, conductivity, conductivity and frequency. Moreover, these fundamental parameters are also dependent on frequency. The frequency dependent reflection and transmission coefficients of some human tissues, especially bone tissues are computed at frequency range 0 to 10 GHZ using MATLAB.
Keywords: Electromagnetic waves, transmission coefficients, permittivity, conductivity, human tissues
Abstract: There is huge change in technology, so the rate of people of all ages attracted towards electronic gadgets is increasing. In different type of industries the electronic devices like smart card reader, barcode and RFID scanner having more usage. This type of gadgets also required in supermarkets. In the existing, in the mall every person takes product put into trolley. After the shopping is done that person have to stand in the queue for billing. In the billing process a sell person scan barcode of each and every product and gives final bill. This process is very time consuming and it becomes worst on holidays, special offers or weekends.
To overcome that we have been developed a smart way for shopping in malls. Each and every product has RFID tag instead of barcode. The smart trolley will have RFID reader, LCD display. When a person put any product in the trolley it will scan and the cost, name and expire date of the product will display. Cost will add into final bill. Bill will be stored in microcontroller memory. It will transfer from RF transmitter to RF receiver. Receiver will transfer this information to the PC through serial communication. For this project we used Embedded C and VB6.0 software
Keywords: Embedded, RFID tags, reader, Microcontroller LPC2148.
Optimal allocation of DG unit for the radial distribution system using genetic algorithm
T.MONISH KUMAR, DR.V.GANESH
DOI: 10.17148/IJIREEICE.2015.3118
Abstract: This paper proposes a Genetic Algorithm (GA) based technique for the optimal allocation of Distributed Generation (DG) units in the power systems. In this paper the main aim is to decide optimal number size and location of DG units for voltage profile improvement and power loss reduction in distribution network. Wind based type of DG is considered and distributed load flow is used to calculate exact power loss. Load flow algorithm is combined appropriately with GA till access to acceptable results of this operation. The suggested method is programmed under MATLAB software. The effectiveness of the proposed methodology was tested on Standard IEEE 37 bus system.
Keywords: Distributed Generation (DG), Genetic Algorithm (GA),Probability Density Function(PDF), Local Distributed Company(LDC), Radial Distribution system(RDS) , Net Present Value(NPV), Risk Factor(RF).
H-infinity PID controller for a Ball and Beam System
AKHIL JOSE, AVINASHE K K, DHANOJ M, E.S. YADAV
DOI: 10.17148/IJIREEICE.2015.3119
Abstract: Ball and beam system is a benchmark system to study various control algorithms. It consists of a beam that can be tilted by a DC servo motor and a ball rolling back and forth on the top of the beam. The main reason for its acceptance in labs across the globe is its property that it is open loop unstable. It can serve as a conventional tool for implementation of many classical and modern control system design method. In the paper, the theory of H-infinity control is used to design a control system for the ball and beam system. The theory of Robust control is extended to design a robust PID controller. Controller parameter values for PID controller i.e. gains are found from the robust controller designed.
Keywords: Robust controller, R obust P ID , H-i nfi n i t y, Ball and Bea m .
Automatic irrigation system on sensing soil moisture content
NAGARAJAPANDIAN M, RAM PRASANTH U, SELVA KUMAR G, TAMIL SELVAN S
DOI: 10.17148/IJIREEICE.2015.3120
Abstract: This project on "Automatic Irrigation System on Sensing Soil Moisture Content" is intended to create an automated irrigation mechanism which turns the pumping motor ON and OFF on detecting the dampness content of the earth. In the domain of farming, utilization of appropriate means of irrigation is significant. The benefit of employing these techniques is to decrease human interference and still make certain appropriate irrigation. This automated irrigation project brings into play an Arduino board ATmega328 micro-controller ,is programmed to collect the input signal of changeable dampness circumstances of the earth via dampness detecting system.
Optimal sizing of solar photovoltaic–Wind hybrid system
POOJA, DR. TARLOCHAN KAUR
DOI: 10.17148/IJIREEICE.2015.3121
Abstract: Increase in energy demand has made the renewable resources more attractive. Additionally, use of renewable energy sources reduces combustion of fossil fuels and the consequent CO2 emission which is the principal cause of global warming. The concept of photovoltaic-Wind hybrid system is well known and currently thousands of PV-Wind based power systems are being deployed worldwide, for providing power to small, remote, grid-independent applications. This paper shows the way to design the aspects of a hybrid power system that will target remote users. It emphasizes the renewable hybrid power system to obtain a reliable autonomous system with the optimization of the components size and the improvement of the cost. The system can provide electricity for a remote located village. The main power of the hybrid system comes from the photovoltaic panels and wind generators, while the batteries are used as backup units. The optimization software used for this paper is HOMER. HOMER is a design model that determines the optimal architecture and control strategy of the hybrid system. The simulation results indicate that the proposed hybrid system would be a feasible solution for distributed generation of electric power for stand-alone applications at remote locations
Abstract: Aiming further to reduce its switching losses, an appropriate discontinuous modulation scheme is proposed and studied here in detail to doubly ensure that maxi-mal reduction of commutations is achieved. With an appropriately designed control scheme had incorporated with nine-switch converter is shown to favorably raise the overall power quality and voltage mitigation hence justifying its role as a power conditioner at a reduced semiconductor cost. A nine- switch power converter having two sets of out-put terminals was recently proposed in addition of the traditional back- to-back power converter that uses 12 switches in total. The nine-switch converter had already been proven to have certain advantages, in addition to its component saving topological features. Despite these advantages, the nine-switch converter has so requiring an oversized dc-link capacitor, limited amplitude sharing, and constrained phase shift between its two sets of output terminals. Instead of accepting these tradeoffs as limitations, a nine-switch power conditioner is proposed here that virtually ―converts‖ most of these topological shortfalls are overcome into interesting performance advantages.
Keywords: voltage sag, mitigation, pulse-width modulation, nine-switch converter, power conditioner, power quality.
Minimization of leakage current through horizontal step doping in SOI MOSFETs
PRIYANKA PARMAR, ANSHULJAIN, ABHAY KHEDKAR
DOI: 10.17148/IJIREEICE.2015.3123
Abstract: As technology scales, sub-threshold leakage currents grow exponentially and become an increasingly large component of total power dissipation. To improve performance of the MOSFETs, doping profile of channel is changed. In this paper, we present comparison of uniform doping (UD), horizontal high source side doping (HHSS) &horizontal high drain side doping (HHDS) and draw the various characteristics i.e. channel electric field, surface potential & sub threshold leakage current .our results show that the horizontal high source sidedoping exhibit excellent properties not only higher mobility but also hot electron degradation improvement and better reliability. Therefore, refer to the results, horizontal high source side doping structure has superior performances in comparison with uniform and horizontal high drain side doping (HHDS). All the device simulations are performed using SILVACO Atlas device simulator.
Keywords: Uniform doping (UD), Horizontal high source side doping (HHSS), Horizontal high drain side doping (HHDS), short channel effects (SCEs), ATLAS.
Improving the loadability of the wind integrated power system using STATCOM placed at an optimal location
SUJITHA G.V.N, B.NARASIMHA REDDY
DOI: 10.17148/IJIREEICE.2015.3124
Abstract: Voltage instability is a major problem that is attracting worldwide interest because of its consequence of voltage collapses. These days’ Kerala power system operate closer to their stability limits because of the economic considerations, making large amount of power transfer from long distance and an inadequate supply of reactive power which contribute to system voltage instability that eventually leads to voltage collapse. So the stability margin has to be estimated and to know the loadability of the power system is essential in the real time system for voltage stability assessment. This paper investigates the enhancement of voltage stability using Static Compensator (STATCOM) in a wind integrated Central Travancore wind integrated power system. Wind energy is gaining attention among a variety of renewable energy resources mainly because it is a clean source of energy, renewable and also its running cost and maintenance cost is very less compared to other energy sources. Wind generation requires some device to smoothen the output from a wind turbine and a STATCOM connected to the bus performs this operation along with the property of voltage stability enhancement. The studies made in this paper are done with power system analysis toolbox (PSAT), a powerful toolbox in MATLAB for power system analysis.
Keywords: Voltage stability, P-V curve, maximum loading point, STATCOM, wind integrated power system.
Control and Monitoring of pH process using Fuzzy Based Controller
MANOJ V, VARUNKUMAR S, MANORANJITH R, V.RADHIKA
DOI: 10.17148/IJIREEICE.2015.3125
Abstract: In today scenario Industries use different types of process variables and parameters for measurement. Among that pH is the most important parameter. These pH measurements are prominent in the industries like food & beverage, power plant, paper industries, paramedical industries etc. The smaller change in pH (amount of acid added, base solution and time) will lead to tedious effects in the process. The control of the pH process is also non-linear in nature and maintaining the pH value in the process is difficult for the desired transient response. In order to reduce problems fuzzy based system was designed and it is efficient than conventional integral controllers.
Keywords: Control of pH process, Fuzzy logic, MATLAB.
Electronic-Nose Technology and its Application -A Systematic Survey
PRANJAL KALITA, MANASH PROTIM SAIKIA, N.H.SINGH
DOI: 10.17148/IJIREEICE.2015.3126
Abstract: Electronic Nose is one of the most advance device in the field of sensor technology. It is responsible for the automated detection and classification of gases, odors and vapors. This paper reviews the three components of Electronic Nose i.e. sample handling, detection system, data processing system. It outlines the range of sensors their principles, advantages and disadvantages. It describe the data processing through pattern recognition process. It also outlines the enormous benefits of Electronic Nose in the field of food control, clinical diagnosis, cosmetics, environmental factors, garbage control and detection of plant diseases.
Comparative study of Metal Antenna &Plasma Antenna
PRAMOD BHAVARTHE, LEENA GOVEKAR, PRITI TYAGI
DOI: 10.17148/IJIREEICE.2015.3127
Abstract: Metal antennas currently in implementation use metallic conductor as guiding medium for electromagnetic Radiations. Plasma antennas uses ionized medium. The plasma antenna is a radiofrequency antenna formed by a plasma columns, filaments or sheets, which are excited by a surface wave. The relevance of this device is how rapidly it can be turned on and off only applying an electrical pulse. In this paper we have discussed the basic theory, operation of the plasma antenna. We have also given the features, advantages and applications for the same.
Keywords: Plasma Antenna, Plasma frequency, ionized gas, metal antenna