Antenna Definition and 418 Threads

Hey guys, I need to make an extremely powerful antenna that will pick up RF in the air or just to get ambient electricty.

Hello, I am afraid this might be a simple question but I am really confused. I am currently working with ferrite core coil antennas, and I am having trouble at understanding their directivity. The cylindrical ferrite core is placed in the middle of the loops. What I have read is that...

First of all, excuse me if this question is too basic: I feel like it shouldn't be a struggle to understand, but the fact is it is. We put up an antenna to play with radio a little, and someone we were working with showed us that there's a reading on the voltmeter without any of the equipment...

A high Q antenna basically means the antenna stores a large amount of energy in the near fields compared with the electromagnetic energy radiated per cycle? When the alternating current momentarily stops in our half-wave antenna charge density is maximum at the ends of the antenna, and the...

I'm trying to understand antenna theory again, and I'm again stumped by the concept of VSW (voltage standing waves). I understand standing waves, I remember these from a level physics, however I do not really understand how voltage can be a wave, and how it reflects. From my understanding of...

I have a Clear wireless broadband box at the place I'm renting a room at, but I'm at the outer edge of the tower's range. I want to boost the signal strength using a directional antenna. There are a number of old DISH and DirecTV satellite receivers floating about, and I can get one for free...

Homework Statement 1) H-plane patterns of rectangular microstrip antenna, open-ended waveguide antenna and small horn antenna are measured and shown in the table below. Assuming the small horn antenna as reference antenna with a gain of G_{smallhorn} = 8dB Obtain the gains of the other two...

I wasn't sure whether to post this question in biology or physics. I'm stumped on a couple experiments. Here are the basic experiments. I have people wash their hands and dry them off and then hold onto the probes of a volt meter. To my surprise some people give a reading as high as...

I was playing with an old crt TV and a small loop antenna earlier and noticed that when I hold the antenna vertically in front of the TV I get one solid spike at around 15 kHz. When I hold the antenna horizontally I get a multitude of spikes that are not there when I turn off the TV. This...

Hi guys, It's been 15 years since I played with radios, and I've basically forgotten everything. Do you think I'm on the right track with this problem? Do you have any suggestions for the circuit needed for the generator and/or receiving filter described in the last two paragraphs? Or maybe...

What must I do to maximize the voltage received from an antenna? Also, what kind of rectifier diode has the lowest voltage cut?

Homework Statement Homework Equations The Attempt at a Solution see last attachment I am not sure if I used the right equations or not.

Homework Statement A satellite link has a transmitted power output of 0.5W. This power is increased in the direction of transmission by the transmitter antenna, which has a 20dB gain. The RF signal is attenuated by a path loss of 200 dB. The total noise level at the receiver input is estimated...

Homework Statement Homework Equations see attached imageThe Attempt at a Solution I'm not sure where to begin with this one. We did a similar problem with a half-wave antenna, where I=I_0 cos(2πz/λ) and it was centered at the origin, so cos = 1 when z = 0. So here I figured if we place the...

Homework Statement The question is " Two large boulders lie between the house and Farmer Joe's favorite radio station. Farmer Joe cannot put the antenna on his house because the howl of the wind through it keeps Mrs Joe up all night. Where is the next best place Farmer Joe can put his antenna...

I am working with an application where we have a magnet in close proximity to an antenna in the 20 - 25 GHz range. If there IS and affect of the magnet to the antenna's transmission, does the "near field" calculation apply (λ/2xpi)? If the antenna is out of the near field, is there no affect...

Hello everyone, I'm currently working on a RF energy harvesting system. I need a transceiver like characteristic. But instead of transmitting and receiving into the same plane. I need the energy to be received on one side and then transmit on another side. Basically follow the diagram...

Hi all, Is it possible to find the direction of a source in 4 quadrants using directional antenna? I am thinking of setting up 4 directional antennas, facing to 4 quadrants, and they will receive the waves from the according quadrants. What do you guys think about this? And is there any...

I'm currently writing a report on antennas and I am really struggling to understand the theory. Here's what I've got so far; Basics: .A moving charge causes a magnetic field .If the direction of movement is reversed, so is the direction of the magnetic field .A non moving charge has...

When finding the effective aperture of an antenna we use: A_{eff}\;=\;D_0\frac{\lambda^2}{4\pi}\;\hbox{ where }\;\frac{\lambda^2}{4\pi}\;\hbox { is the effective aperture of a isotropic antenna.} I read from Wikipedia and other sources that in order to use this equation, you assume the...

Hi PF, I want a good book to follow for electro magnetics , transmission lines and antennas etc. I would prefer the style of Richard G Lyons (DSP) or Hugh hildreth Skilling (Fundamentals of electric waves). I love the style in book 'Fundamentals of electric waves'. But it deals no...

I want to find power of the electromagnetic waves generated from a welding cable. I built my own coil antenna that is 6.5 inches in diameter (circular) with 50 turns and hooked up the ends to a digital oscilloscope to measure the voltage (the internal resistance is 1MΩ if it matters). I...

Should it be straightforward to estimate the number of radio wavelength photons emitted per electron per cycle (or is it number of electron cycles per photon) of a half wavelength radio antenna running at 100MHz and 1000 watts power output? Is it many photons per cycle per electron or is it many...

Hello. I was wondering if someone could explain to someone with no electrical engineering background where would one place the resonator whose sole responsibility is to amplify sine waves at a particular frequency while ignoring other sine waves. Would this resonator be located by the antenna...

How do you characterize an antenna in receiving mode? The book said a LHC antenna in transmitting mode is RHC in receiving mode. Also if the antenna is LHC in transmitting mode, it's transmission characteristic is defined as \hat {E}_{(z,t)}=\frac{\hat {x}+\hat {y} j}{\sqrt{2}}. But the same...

If visible light is part of the EM spectrum just like radio waves, is it possible to construct a radio like antenna (metal pronged structure) to detect them?

With a 5W FM transmitter and a normal dipole antenna , to what range can I transmit. To be more specific, what will be the radiation pattern like (Can I get signal uniformly as in a circle where the center is antenna). Using which antenna, can I achieve maximum range omnidirectionally...

Hello, I recently just started a Masters program in Electrical Engineering with a focus on Electromagnetics. I'm also currently working for a large engineering company. I'm considering purchasing the student version of Matlab so I can work on antenna problems. What packages should I...

Hi everyone, I'm Designing a BiQuad antenna for WiFi applications. The design and optimization are relatively simple but i need some references of the theory behind this antenna. I'm reading some theory of Bi-Conic Antennas but it's a bit difficult to extrapolate the idea between both...

antenna circuit theory help! Im having trouble understanding vswr and current path in an antenna system. Example is the dipole...Ive read that the parasitic capacitance between the 2 wires forms the complete circuit but then I read about standing waves that reflect at the open circuit. My...

why does the bending of antenna is important?why we can't just use two parallel wire to radiate energy? thanks.

I have been trying to understand polarization match in the text from Balanis. The first attachment is the text scanned from the text explaining the polarization of an antenna in RECEIVING mode. I try to understand what the book said and I came up with my interpretation in my writing and drawings...

I'm learning about an antenna theory and have a few question. According to the attached image. Can anybody explain what's going on in the image? I've done lots of calculation, but still have no idea what's going on. My question is 1. How dipole produce a loop of electric field...

Hello every body! Last weak I decided to make a corner reflector antenna for reciving TV signal.Now I need design and construction theory about it with total idea.I also need circuit diagram.Please share with me if anybody knows. sorry for my bad English. Thanks

I understand a changing current in a wire gives way to an opposite magnetic field that resists the induced magnetic field, until there is no change in magnetic field, then you're left with a constant induced magnetic field. So my confusion with the antenna is when an electron rapidly...

I have constructed a small one-transistor regenerative receiver, and I have been getting weird results with reception. I have noticed that simply touching parts of the radio, such as the antenna or around where the antenna is attached, will provide great reception. However, when I am not...

How does it interact with the magnetic and electric fields of the radio waves while receiving them?

How exactly does an antenna work? When Alternating current is produced into the conducting rod why does it propagate into space as electromagnetic waves or in other words what causes the current to leave the antenna? Also when electromagnetic waves interact with a receiving antenna what...

Homework Statement Plot and compare the path loss (dB) for the free-space and plane-Earth models at 800MHz vs distance on a logarithmic scale for distances from 1m to 40Km. Assume that the antennas are isotropic and have a height of 10m Homework Equations Free space: P_R=\frac{P_T G_T...

Hi everyone! I need your help to design an antenna which produces current. Since i m not an engineer & have no technical knowledge. So, here is the principle! Guid me how to design an antenna for radio waves or any other one which will produce a maximum attainable current from these by...

I would like to build an antenna that will be used in a very remote area to improve our cell signals. We have access to the GSM 850 (824.2 - 849.0 Uplink | 869.2 - 894.0 Downlink). I need help in calculating the antenna length based on the frequency and need advice on the most effective...

Homework Statement Determine the effective area (Aeff) for a short dipole with L = λ/60 and λ/2 dipole. If the wires used for dipoles has radii a = 1 cm compare Aeff with the physical area. G(short dipole) = 1.5 G(half wave dipole) = 1.64 Homework Equations Aeff = G* λ2/4*pi The...

if I were to disassemble the cellphone and try to extract the "antenna" component, what would I get? Is it a long straight cable? Or a mesh? Can it actually be extracted out of the case or is it somehow embedded into "motherboard"?

Hi I have taken a very rudimentary course on antenna theory, now i am interested in further deepening my knowledge. I have bought myself Balanis's book on antenna theory, I need some guidance regarding what chapters should i study as it is quite a large book. Secondly, after i have got...

I've been trying to figure out how an inductor is different from an antenna. It's obvious that the inductor has more inductance than an antenna would, but let me try to explain it from my point of view. My current research project for school (lasting this year and into my senior year) is on the...

After googleing the formula to calculate impedance of a radio antenna, I came up with this formula Z = R + jX where X is reactance and R is resistance. I figured resistance could be measured with an ohmmeter. Then, it seems like there are two kinds of reactances, capacitive and inductive. The...

Homework Statement "Your vacation cabin in the woods is at the very fringe of the reception area for the FM radio station in the previous question (that broadcasts at 100 mHz). In order to maximize your chances of receiving your favorite tunes clearly from this station, you should adjust the...

Currently I am working on a project which involves putting a metal shaft into a microwave which extends out of the microwave as well. After grounding the shaft I ran a test to look at the effect of microwave leakage out of the microwave due to an antenna effect from the shaft. There was...

For a project I was going to build a simple 160MHz transmitter/receiver using a Yagi-Uda antenna arrangement and a resonant circuit. In some diagrams I notice that there appear to be two antenna outputs/inputs. Are these outputs spliced somewhere before reaching the LC circuit, or is one end...

Homework Statement Determine the SNR for the spacecraft that uses a transmitter power of 16 W at a frequency of 2.4 GHz. The transmitter and receiver antenna gain are 28 dBi and 60 dBi, respectively. The distance from the space- craft to ground is 2 ϫ 1010 m, the effective noise temperature...