Antennas Definition and 96 Threads

I would like to simulate two small interacting antenna's with fields and forces in 3D. They can be simple wire antenna. I am asking if there is a recommendation for software that can reasonably accurately handle that which is free? Thanks.

The title pretty much covers it. I'm having to calculate the field induced inside the human body by an antenna in the near field (essentially, a phone placed close to a user's head), and I'm drawing a blank on how to relate the field generated by the antenna to the field induced inside the...

Hello everyone, I was asking myself about electric field strength estimation at a distance d from - in my case - a half wave dipole antenna. There are pretty much a lot of information about this on internet or in books but still, there are a few things that are confusing to me that I would...

Summary:: I am stuck on a problem on dish antenna C/N and it's relation to frequency. Please see below for thought process. Problem Statement: , Link budget formula in dB form: Pr = Pt + Gt + Gr + 20*log10(lambda/(4*pi*distance)) - Losses [dB] C/N = Pr - Pn [dB], where Pn = 10*log10(k*T*B)...

Consider the following situation. Two identical monopole antennas are placed in a field with distance d. One of them is used to receive signals and the other is disconnected and can therefor be considered to be just a metal rod (my guess). A plane wave of a single frequency is coming from a...

Although problem says sketch, what I really want is the formulae by θ for the radiation. After trying this for a while I cheated and looked at the solution. I still can't figure out the steps on how to get to the solution. the answer is: What I tried: I'll assume that the intensity from a...

I have written a solver for my thesis which determines various parameters of a conical horn antenna for astronomy application. It is done with Mode Matching Technique (MMT) and some Rumsey's integrals for the aperture free space transitions. I have made some goal functions with the solver which...

Homework Statement: More of a conceptual question than a homework question. Maximizing radiation southward and minimizing it northward. Homework Equations: (See picture in attempt at solution) For two antennas separated along the north-south direction, operating with the same amplitude...

Hello! This may be an obvious idea and I feel silly for asking this, but just out of curiosity, if I have a large dish satellite where I could fit three antenna transmitters in the center that send different types of signals (a broad-band radio antenna, an ultrasonic antenna/sensor, and a...

For RF devices that charge/take in energy through RF waves, does it only take in electricity from a frequency it's wired/set to pickup/receive or does it get electricity from all RF waves? Can an antenna fold in (collapse but still connect like tent poles) and still remain operational like it...

Does it take more electrical energy to transmit HF and lower frequencies than it takes to transmit VHF and above? Are there any wavelengths beyond radio waves and gamma rays? Is it true that the lower the frequency, the lower the amount of data that's being sent? I read on this wiki that...

I recently bought a KiwiSDR and it's my first SDR so far. I was wondering, what antennas you guys recommendation for it and whether this recommended antenna is truly good for it (it was listed on the KiwiSDR site as a recommended antenna, but it's a bit pricey for me). I'm trying to find signals...

I want to use small molecular - preferably CNT - "antennas" to produce THz signals to monitor activity in biological systems. After some googling, I've been reading things like "absorption spectra", "energy bands", "spectroscopy", as well as a bunch of antenna-science related jargon... I need...

Would it be possible in theory to develop a material with very slow velocity factor to build dipoles immersed in a slow velocity factor gas in order to make much smaller HF antennas?

Why can't antennas be made smaller and smaller? Assuming we implement the following measures : - 1. use room temperature superconductor to eliminate the ohmic loss of antenna 2. reduce the thermal noise of antenna by lowering its temperature 3. Perfect impedance matching network by means of...

I'm extremely interested in the self resonant frequency of an inductor. This is to be used as a half wave helical antenna on our ham bands. The usual helical is operated as a ground plane but I have not seen a complete set of design equations for the former. The initial problem with this is...

I have been debating with a friend about a thought experiment that evolved out of an entirely unrelated discussion, but which has now become a subject of argument. Consider a "dual" phased array antenna that has every odd-numbered radiating element driven from input port 1 and every...

I'm curious about anyone that has concrete hands on experience tinkering with very small low frequency antennas. My band of interest is 6, 13 or 27 MHz. I wonder if it is possible to design a very small physical antenna that will radiate with some directivity even if the efficiency is not so...

just stumbled across this article I am sure other tech types like me will appreciate this article ... http://www.mro-network.com/engineering-design/understanding-today-s-antenna-complexitiesenjoy cheers Dave

EE, and life-long science explorer and tinkerer. I look forward to reading the forum, and hopefully contributing at some point. This looks like a great forum! If we weren't limited to 5 tags here, these would have been mine: physics (duh!), relativity, nuclear, antennas, time, radio...

I have a typical problem. I have two bars mobile signal in my attic - none at ground floor level. The reason is a roadside pole transmitter less than 500m away installed down in a dip behind houses (duh!) An electrically powered signal booster is illegal in the UK which atracts a £5000 fine...

Hi the difference between a loop antenna and a magnetic probe (B-Probe) is only that the loop antenna works in far field and B-Probe works in near field? The standard features of magnetic antenna (antenna factor, impedance matching, radiation patterns, efficiency, ecc) have the same definition...

When an RF antenna absorbs a signal, the momentum is transferred in quantized photon-electron interactions. The electrons in the metal will be given both perpendicular momentum (the actual signal information) and momentum in the direction of propagation (shown below): The momentum in the...

Good evening everyone! Given that I have no experience in antenna physics or related areas, I'm studying a paper for a project I will be involved. It is an image sensor for THz e.m. waves and exploits micro-bowtie antennas to "capture" the signal and convert it through a standard CMOS imager...

In Kraus book on antenna (3ed page 203) example 7-4.1 the difference between those antenna is (to my understanding) only the wave length. How could they have different radiation pattern?

First of all I will being with I'm not an electric engineer so I might be out of my wits, but I will give it a try. So I have an instrument which reads relative permittivity using a transmitter and two receiver placed at different distances. The instrument is calibrated to read either in a...

So I came across the following image (from Wikipedia) where the electric and magnetic field lines are depicted for a dipole antenna. From the field lines, it is possible to determine the direction of the poynting vector, using the right-hand rule. If all possible combinations of poynting...

Antennas work with variable current that leads to accelerations and deceleration ofor the electrons, the frequency of the photon or the electromagnetic radiation I want to generate depends on the change in kinetic energy of the electron E= hf= change of kinetic energy of the electron, according...

Antenna Size So I was reading the above thread, and loved the explanation at the end. But my remaining question on Antenna Size is that..Okay I get why for low frequencies we *need* to have bigger antenna, so how it is that people like Hams transmit on lower frequency, long wavelength channels...

I am trying to solve the following two antenna. Perhaps they have already solved in some textbooks. Could anyone advice me where can I find them?

I spotted this "palm tree" in Santa Clara a few days ago. It's in a church parking lot, near some other real palm trees. Pretty clever way for the church to make some extra money on the side from a cell phone provider. My girlfriend spotted a much stealthier cell antenna tower disguised as a...

Alright. I have also a few questions concerning dipol-antennas: first: It has often been said, that the dipol antenna, in order to receive a certain frequency, needs to have a length of λ/2. I don't see a clear reason for that. If one would not know that, one had to calculate the Capacity...

Okay, sorry for my frustration at this fundamental subject, but I am going completely insane not understanding it! All this near-field / far-field stuff is messing with my head. I simply want to know how RF works. Let's start simple. HOW IN THE WORLD IS AN RF SINGAL MADE!? Let's say I have some...

berkeman, I read a post of yours stating that "the house next door a wifi cell tower was more dangerous than the one with the antenna on top" Would you please elaborate? Is this because of the umbrella effect? I am considering buying a home which is next door to a house that installed a wifi...

What are the best universities in the world offering ms programs in applied electromagnetics, radars and Antennas.

Hello, I'm currently working on satellite model for high-school compatition, and I'm not sure if there's a visual difference between a reciver & transmiter antenas (on satellites)... Also, is it possible to satellite to recive a radio wave information from another satellite Thank you

Hey all, I realize a question on this topic has been asked elsewhere, but the links to references they use seem to be dead, so I'll press on! I'm reading some introduction to antenna theory and I've often puzzled on the equation: A_{eff} = \frac{\lambda^2}{4\pi} which relates the effective...

Hi, I've been reading a lot about traveling and standing waves, and i am right now reading about traveling wave antennas, to my understanding ALL antennas should be traveling wave antennas, but this is not the case of what i read online, and there is also not too much information about it. For...

Homework Statement antennas can both receive and emit electromagnetic radiation depending on wetter their connecting cicuit is monitored for, or driven by a current. the pattern of emitted radiation is identical to the pattern for absorbed incident radiation. As shown in the notes, far-field...

Having not been set up with a station for quite a few years I am thinking of setting up an end fed antenna for HF. It seems the only way I will enjoy a little 'hamming' again is to start out simple and quick. Trying to avoid clutter in the middle of the yard. I have enough tower sections get...

Could somebody explain what does mean "infinite wavelength antenna" and what advantages does it have? What is resonant antenna and advantages? http://webcache.googleusercontent.com/search?q=cache:fHdO6P-aoIIJ:dspace.nitrkl.ac.in:8080/dspace/bitstream/2080/1320/1/MMET.pdf+&cd=4&hl=en&ct=clnk&gl=ca

Can anyone provide some literature on antennas spaced apart such that the spacing distance is much less than the wavelength? I am specifically interested in the mutually coupling behaviour as a function of small separation distances.

Hey everybody! I wanted to simulate an antenna in Low Frequency, but I don't know any suitable software for this purpose. I'll appreciate if anybody could help me out... Thanks

How do transmitters convert electrical signals into photon energy?

Consider this: Two antennas are set up in a vacuum. They both radiate electromagnetic waves of the exact same frequency, and an interference pattern can be observed on a screen placed some distance away. Now suppose the emission density was reduced (in both antennas) to one photon at a...

Homework Statement Two radio antennas separated by d = 294 m as shown in the figure below simultaneously broadcast identical signals at the same wavelength. A car travels due north along a straight line at position x = 1 290 m from the center point between the antennas, and its radio...

Homework Statement Two antennas located at points A and B are broadcasting radio waves of frequency 99.0 MHz, perfectly in phase with each other. The two antennas are separated by a distance d= 12.40 m. An observer, P, is located on the x axis, a distance x= 58.0 m from antenna A, so that APB...

Why antenna needs to be smaller in size with higher frequencies (EM waves)? please

Why does a 1/4 wavelength antenna have to be 1/4 wavelength? What property of the wave is responsible for this restriction? I've been trying to understand how a 1/4 wavelength antenna works and the best explanation, relatively speaking, was on the following website...

I'm currently preparing for a challenge exam, and I'm having trouble understanding antennas. My physics book is good, but it is very brief in its section on antennas. I know there are more complicated types of antennas, but let's just stick with the "simple" half-wave antenna (or dipole antenna...