Antenna Definition and 418 Threads

Homework Statement Hello everyone. A 4-way TV antenna amplifier has the following specifications: Bandwidth = 40-862Mhz Gain = 20dB Noise figure = 6 dB Max output = 85dBuV Input impedance = output impedance = 75 ohm Question 1: Calculate the required voltage on the input of the amplifier to...

Hey all, I am trying to do a read through on antenna theory (using Constantine's book) and am wondering if there is any online course that might follow the book or serve as a good reference. I have found pretty good success in supplementing a book with an online course in the past (i.e...

Hello, I've heard in many places that in the "near reactive field" of an antenna which is the region really really close to the antenna, the E and H fields are not perpendicular. But I just can't imagine how that is possible since In Maxwell's 3'rd and 4'th equations it is explicit that the curl...

Given the following: A directional radio wave transmitting antenna which creates a beam (diameter in mm), a current in volts, and a frequency (Hz), is it possible to calculate the em wave voltage (v/m or w/m2) immediately next to the antenna? and then at a distance of 10meters? What...

I'm trying to build a high gain TV antenna. I'm looking to achieve a 75 mile minimum range under most weather conditions. I do have a signal amp board I striped from an OK antenna, that I plan to use as well. I'm trying to specialize the antenna for my viewing market, UHF channels 17-38 (489.25...

I can get some old massive size power transmission cable straight out of the power station. I have the space to erect some posts and go just over 500m but with permission I might get 1km or more. Will use a metal pipe in the ground for ground. This is not technically a dipole, would a dipole...

Just sharing, to explore EM theory you can build a highly directional 3 element yagi antenna and usecfree SDR software to analyse it. The only cost is a SDR receiver if you want quantitative data.If someone wants to edit me I will write a detailed method and parts list including a tone generator...

Hi, my high school astronomy class designs/builds antennas to detect VLF radio for solar flare detection. Recently, and regardless of their design, we get a strange "mirrored" shape to the dB vs frequency plot. The shape of the graph before roughly mid-band is exactly mirrored about the...

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 everyone, Looking for someone in the know regarding RFID reader antenna design. Part of a project I'm working on requires a custom RFID transmitter antenna. If possible, I'd like to design the antenna as an integral part of a steel cylinder. I know there are on-metal tags, but is it...

Hi everybody i want to simulate, low frequency ferrite core receiving antenna . but i can't find a good and complete software or method to do this. what is your suggestion or experience? thanks for your attention.

Hello, I'm currently engaged on a project where I need to design a 3x3 rectangular patch antenna array operating 1.5~5.8GHz on FR4 h=1.6mm substrate. I've studied the single element design and some TL matching techniques like the quarter wavelength but I can't put together a 3x3 elements...

Consider the situation where the electrons in an antenna accelerate from the top of the antenna to the bottom of the antenna once, what would the interference pattern look like if the electromagnetic radiation from the antenna were passed through a double slit apparatus of an appropriate size? I...

Are photons emitted from the stationary protons in a dipole antenna? The protons don't accelerate at any point but their electric field does contribute to the electromagnetic wave.

Hi Ok I have a contradiction in my mind: Patch antenna is called a leaky wave resonant cavity because of the magnetic slots which radiates. We all agree on the fact that they are standing waves with clearly identified max and min as a characteristic of a specific mode inside this cavity...

Hi there, Maybe this is a stupid question. Maybe not. I want to make a statement in my thesis that says that all radar antennas on satellites derive the EM field by: receiving the time-varying H field, and from the induced current derive the EM field. Am I correct in saying that? Or are there...

Homework Statement The half wavelength "dipole" loop roof television antenna is most sensitive to electromagnetic waves with a wavelength twice the width of the antenna. The frequency of the waves for TV channel 10 is 200 MHz. If you want to optimize the TV reception for channel 10, how wide...

I'm using the DN007 antenna: http://www.ti.com/lit/an/swra351a/swra351a.pdf and I've managed to get the same loss/response in CST as what they have in their data sheet, however I'm wondering how I can increase the BW? It passes through ~2.4GHz, but I'd like to increase that to include about...

Hi this is my first post here. Sorry for this naive question xD I want to calculate antenna gain for which I need the horizontal Φ and vertical θ angle of an antenna beam. The formula for gain is. is it ok to convert the rectangular coordinates of antenna into spherical coordinates and compute...

Alright so I am building a few half wavelength dipole antennas for a project and was wondering how large the space should be between each side of the dipole antenna. I have asked a radio forum and they could not help me so I came here. Thanks. Also I herd that an 1 and a half wavelength...

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...

Homework Statement I have attached the photo of the problem below. Homework EquationsThe Attempt at a Solution According to me answer should be (a) but book is giving answer as (d).

Hi Forum, Couple of pheromone here: Metal reflects EM waves (visible light and lower) Antenna absorbs EM waves electrical circuit reflects high frequency signals inside the circuit electrical wire with the right length and right signal becomes an open-circuit/Antenna I think my question is...

I'm under the impression that if you increase the frequency of a circuit coupled to an antenna, for the same amount of photons emitted, the frequency of those photons will increase therefore having them carry out more energy total, thus increasing the amount of energy required to power the...

I have an Antenna that receives signal coming from a wide band of distances, 10-2000 meters from a 10mW transmitter. I am working with 868 MHz band. What is the cheapest method ( or cheapest circuit ) to amplify this signal with an Automatic Gain Control LNA so that the received signal stays...

Assume a 2D problem. Given a linear antenna array, let's say 3 antennas distributed around the z axis, how could we extract the incidence angle of the received wave? Having 3 antennas equally spaced by λ/2 in the z axis and connected to each other, the result gain would be a function of ϑ (angle...

When making an extension from linear dipole antennas to small circular antennas, I am only coming across expressions for a magnetic dipole moment (as opposed to having just an electric dipole moment for a linear dipole antenna). The expression being: m = πr2I at its peak The above expression...

Homework Statement A thin linear antenna of length ##d## is excited in such a way that it carries the sinusoidal current ##I(t) = I_0 \sin(2\pi z/d)e^{ i\omega t}##, where ##\omega = 2\pi c/d##. (i) Beginning with the exact solution for the vector potential in Lorenz gauge, calculate the power...

Hi all, I have a problem to firstly understand and secondly solve this problem : here is the Problem : Consider three (coherent) antennas variously arranged on the x-y-plane where each individual antenna radiates an isotropic electric field E(x). 1 - Write down an expression for the far-field...

I'm trying to explain an FM or AM radio receiver using photons. When the photons are absorbed by the antenna, they arrive in discrete pulses, where in the case of FM, each wave front contains photons of the same energy (frequency) and the following wave fronts contain photons of different...

I want to find a simple example of using the Feynman propagator: 1/(|x-x'|2-(t-t')2) and also to show that no signals an travel faster than light. So I was thinking about waves emitted from an antenna. Tell me if I got this right? Assume a static source in space at x=0 and varying in time...

Hello all, I have a DJI Phantom 2 Vision+ and I just recently had it painted. It is painted like a car would be painted. Ever since the new paint job, my drone is not flying right. It is displaying symptoms of Radio Frequency (RF) interference. The main issue is that it is now flying...

Homework Statement Assume that the power radiated by the television transmitter uniformly fills the upper hemisphere. A UHF television with a single-turn circular loop antenna of radius 8 cm requires a maximum induced voltage above 24 mV for operation. The speed of light is 2.99792 × 108 m/s...

Hi, I need to select a passive 50 Ohm surface mount chip Antenna (size 3.2x1.6x1.2 mm) for my WiFi radio. Can I use any 50 Ohm chip Antenna available?

Hey guys, currently I am working on my diploma thesis in the field of beam design for mobile communication. I created a linear array with N elements and computed the corresponding Array Factor with the help of the chebyshev distribution. I assume my Element Factor to have its maximum at 90°...

Hi folks, Currently working on a project at university, and I have a question on antenna theory. When talking about the "effective aperture" of an antenna, what exactly is this ? I have found this explanation but I can't quite get my head round it... "effective aperture parameter describes...

Hey all, This question may sound daft, but how do I normalize angular frequency? For a little background: I'm trying to optimize some circuits, and I've managed to write some successful code using the "Design of Ultra Wideband Antenna Matching Networks" book, but the code requires normalized...

Can someone please help me understand how two-antenna method is used to measure gain of an antenna ? I could't even find literature on it, please if anyone could even suggest any document that would also be great. Thanks.

Does anyone know what the radiation patter is suppose to look like for a quarter wave V shaped antenna with the angles pi/4 and 3pi/4. The MATLAB looks like 2 lobes which is not what I was expecting. I was expecting 2 dounuts in the respective angles.

The AM/FM radio on my boat has a simple wire about 70 cm long as an antenna. It is much less effective than a car antenna. I say that because it has difficulty picking up stations that the car gets easily. At sunrise/sunset the effects of radio propagation become evident as the stations...

I'm an automotive technician working at a dealership and I am working on a car with intermittent issues with wireless communication with the tire pressure sensors which are mounted inside each wheel. I went searching for the location of the particular antenna that serves the tire pressure...

Hi, I've got some questions about how the quarter wave cavity duplexer works in this configuration. From what I've read the cavities need to be connected together with 1/4 wavelength sections of cable. I'm not sure what the purpose of 1/2 cabling is. I'm told that its to transform the low...

How can my cell phone WiFi antenna reach my far-away router with a small antenna but the router needs a large antenna to reach the same distance? Do the Wi-Fi/radio signals from my cell phone antenna have to reach my Wi-Fi router to connect to it or do the radio signals have to meet in the...

Hello, I am an electrical engineering graduate student building an antenna which will be mounted under the fuselage of twin engine airplane which will be taking remote sensing measurements. Besides the antenna design I have also been tasked with developing the method of deployment as well...

I saw this antenna on a residential rooftop yesterday (in the US). I'm guessing it is a over-the-air Digital TV antenna, but I don't recognize the vertical bow tie structure. The antenna is about half a meter tall. Any ideas?

I'm trying to work out what 3.d) is meant to be. I'm not entirely sure which part of the antenna it is referring to; I assume it's referring to width of the gap between the feed and the patch. If this is the case, I have no idea what width one would want to make it. I would've thought as small...

Hello Everyone, I just want to get an idea about which schools offer the best programs for antenna engineering. I'm an electrical engineering undergrad wanting to get a masters in electrical engineering with an emphasis in antenna design and/or rf/microwave engineering (circuits and...

I have a wifi card for a cisco router that has two antennas spaced about an inch apart. The antennas can pivot so that the distance between the same point on either antenna can change. Since the antennas don't remain a wavelength multiple apart at all points on them, why is it that they don't...

Homework Statement A 600W carrier wave is modulated to a depth of 75%by a 400Hz sine wave. Find the total antenna power. (1) 769W (2) 796W (3) 679W (4) 637.5W Homework Equations The Attempt at a Solution I honestly don't know what to do here. I have tried to find a...

Consider a small, thin loop in the (x,y) plane centered in the origin and with radius a. We are interested in the vector potential \mathbf{A} generated by the loop at a point P(r, \theta, \phi), with 2 \pi a \ll r, so at a great distance (moreover, a \ll \lambda). We need two coordinates...