Antenna Definition and 418 Threads

Hi. In this video around 6:45, this guy builds a simple dipole antenna with an LED and capacitor in parallel in the center. The LED flickers when close to a transmitting cellphone. Since the LED only let's current pass in one direction, shouldn't this quickly lead to a charge imbalance between...

Hello Experts, I have created this thread especially for clearing some of the important concepts of Antenna and Designing Issues. I have a question for all of you, related to Dipole Antenna. I have designed a Folded Dipole Antenna resonating at center Frequency of 145.800MHz. This antenna is...

Is a small-loop antenna a dipole or a monopole? Is a (small) 8-shape antenna a dipole or a monopole? Is a 8-shape antenna a dipole antenna?

The left figure is the top view the right one is the side view. I would describe it as an S shape... Why do people design such an antenna?

Is there an antenna of S shape or perhaps a butterfly shape? What is the benefit of such design?

WiKi indicate Millimetre Wave Antennas for Gigabit Wireless Communications: A Practical Guide to Design and Analysis in a System Context Huang, Kao‐Cheng ; Edwards, David J. Chichester, UK: John Wiley & Sons, Ltd But our library do not have this book. Has anyone know other book on this...

There are many website about the apparatus of Hertz's experiments, i.e. http://www.sparkmuseum.com/BOOK_HERTZ.HTM http://earlyradiohistory.us/1901hz.htm http://people.seas.harvard.edu/~jones/cscie129/nu_lectures/lecture6/hertz/Hertz_exp.html There are many pictures showing the apparatus of...

Could an antenna made from a non-conductor or a poor conductor?

Hi group, I have a question regarding to detect the location of the antenna. I read this link: https://en.wikipedia.org/wiki/Plane_wave In the "Complex exponential form" part, the equation: U(r,t) = U0 * exp(j*(k.r - w*t) as the function of location and time U0 = A0 * exp(j*phi) : A0 and...

I have a question regarding how a Yagi type antenna radiating its energy with respect to faithfully replicating the original signal. So let's say you have a FM modulating signal, F(x(t)) whereas x(t) is the data, and F(t) is the carrier, so basically x(t) would FM modulate the carrier F(x)...

My question stems from the Cosmic-1 satellites using single antennas for radio occultation and the cosmic-2 sats that will use a phased array antenna. I've done a fair amount of research in regards to the phased array antenna. Overall it seems to improve the signal to noise ratio when making...

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...

I am trying to create a phase sweeper at 31.4KHz(and constant 5V) for a small antenna array that consists 2 antennas. If I can create 2 signals with a frequency difference < 1Hz it's okay too(It will be nearly same) as long as I can control that difference because I need to change phase at a...

Hi everyone, I am a new student who is studying on collecting data from TV signal. I hope everyone can help me for ideas. I am having spectrum analyzer which can define a TV station around me, so I chose 4 stations WHUT-TV [584MHz 590MHz], WPXN-TV [590MHz 596MHz], WTTG [60 MHz 608MHz], and WNVC...

When antenna receive the radio signal does it reduce the actual radio signal strength or strength indeed depends on the dispersion loss and other dielectric absorption? If antenna doesn’t reduce the radio signal strength(power), how it generates the current in the receiving antenna circuit? How...

I came across these videos that show how electric field looks around the dipole antenna at three different distances Far field Near field Something between far and near field That got me thinking - there is a point when the field is reversing and the electric field closes into a loop and...

Homework Statement A radio broadcast antenna is located at the top of a steep tall mountain. The antenna is broadcasting 104.3 FM (in Megahertz) with a power of 5.00 kilowatts. What is the peak intensity of the signal at a receiving antenna located 25.0 km away? Homework Equations Honestly...

hi, my question is in regard of a printed (microstrip) dipole antenna. I know that a balun acts as an unbalanced to balanced line transformer. (in my case of the dipole antenna: the coaxial feed is unbalanced and the half-wave diple antenna is balanced, so i need a balun.) But what exactly does...

I've searched high and low for data regarding this from scientific papers to books and I cannot find anything in regards to the approximate impedance to excite a vacuum vessel to plasma state. In particular I want to built a RF Plasma cleaning chamber, however, I am not sure how to design the...

I expect that others have already asked and answers this question but I could not find it with Google searches. My thought of this apparent antenna reciprocity violation is per below. Since antenna reciprocity states that an antenna will have same characteristics whether used a transmit...

hi there,im pretty new to antenna design, still have a lot of theory to go through, so please be kind. ;)I have to design a linearly polarized microstrip patch antenna (rectangular) that is fed with 2 coaxial probe feeds. The patch should be a square (L=W), so i can place 2 feeds orthogonally...

Hi, a buddy of mine is working on a projecting trying to find the best way to transmit electromagnetic wave frequencies, and he wants to use a horn antenna for his project. I was looking into horn antennas, and I'm just curious, the wiki page leaves two separate equations for gain, one with a...

Hello. I use a group of 4 helix antennas in the band of 1420 MHz. It works fine but by nature directivity is very poor ( around 50° at -3 dB). Is there a way to improve directivity using mechanical, electrical ... devices ?

I was looking up capacitors and the E-field that is produced by a capacitor and I couldn't find much literature about how the E-field changes when AC is flowing through a capacitor. Is this similar to the propagation of an antenna? Do capacitors radiate? Could a capacitor be considered a dipole...

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...

Hello! Is it possible to detect THz radiation (300 GHz - 1 THz) with conductor or dipole antenna used to detect radio waves? I know that THz radiation may be detected in spectroscopic set-ups with a photoconductive antenna based on the semiconductor. In this case, the light from laser create...

Loosely, in terms of string theory, an electron moving back and forth in a radiating antenna is a string moving in space-time. Far away, the electromagnetic radiation of the antenna is made of strings moving in space-time. Can I think of the near electric and magnetic fields surrounding the...

I am looking for a small journal to submit my recent paper. I hope it can 1. have printed version 2. free of publication fee (therefore all IEEE journals are out) 3. listed on SCI It does not matter which country does it belong to. Nor do I mind whether is it small or not. Has anyone any...

Purchased a Netgear R7000 Nighthawk router that has 3 antennas mounted on the back. Is the maximum signal strength in the direction formed by the plane of the 3 antennas (left to right) or perpendicular to that plane (front to back)?

Hello Physics Forums! I'm not an engineer/scientist but I work with antennas and I'm having trouble deciphering the above antenna radiation pattern diagram. I am used to seeing radiation patterns expressed in polar plots. Usually the scale is set to dBi (where the isotropic antenna = 0dBi)...

Hello, Is it possible to derive the electric field of a dipole antenna mathematically? Does it look like a pure dipole far away? I am experimenting with these things and they are a bit mysterious to me. Thanks for your answers!

I am reading Kraus' book on Antenna, Chapter 6. I think Eq. (8) and (9) is his solution for the far field of a small-loop antenna. However, why does he need A (the area) and r both in the equation (8)? A= \pi r^2 and can be simplified?

Jackson discussed two center-fed linear antenna: once at page 412 (section 9.2) the other at page 416 (section 9.4) I just cannot figure out what are the difference? I though they are different method of calculation but (9.56) is different from (9.28).

I am reading Jackson's book on classical electrodynamics. It said in page 412 to 415 (3rd edition) that the total power radiated by a dipole is proportional to k^4 (equation 9.24) quadrupole is proportional to k^6 (equation 9.49) But why does the linear antenna at page 412, which is a dipole...

Homework Statement A radiometer system on a satellite orbiting the Earth at an altitude of 1000km has an antenna of gain 46 dBi pointing at the earth’s surface. The antenna is matched to a receiver with an input noise temperature of 50K and a bandwidth of 10MHz. The sky noise temperature is...

Homework Statement [/B] The diameter and depth of an antenna that is shaped like a paraboloid are ##d = 2.0m## and ##s = 0.5m## respectively. The antenna is set up so that its axis of symmetry is at an angle ##\theta = 30^{\circ}## from it's usual vertical orientation. How much can the antenna...

Hi Me and a couple of class mates are working on our bachelor's project of which the mission is to measure the temperature of the sun using a parabolic antenna. We are having great troubles trying to come up with an equation relating the antenna temperature (which we are able to calculate with...

I just read that if we have an antenna, then if the radiation resistance in the antenna is small, then the antenna is an inefficient antenna? This seems somehow counter intuitive to me. Could anyone help explain?

I have a few doubts regarding antenna radiation and propogation. Kindly look into it and clarify. Consider a Hertzian dipole antenna, DOUBT # 1. Generally, when the power is mentioned for an antenna elements such as the power dissipated across radiation resistance(Rrad) P radiated =...

I use this for my backyard hobby (amateur) design work; don't know how valid it is but has always seemed to be accurate. does anyone know if similar downloads for designing other antenna types beside yagi's. just want to have some fun, no specific application.

Homework Statement Greetings. Can someone give me hint how to solve following problem: Homework Equations From my understanding, you need following formula to solve problem: and then potential can be obtained by integrating over the current distribution. But right now these foormuas really...

I don't know why I was persuaded that in the free space, the electric field of an EM wave is always orthogonal to the direction of propagation. I've recently read my old textbook, and found that this is true only when the wave is far from the emitting source. But if I've understood right the...

This question is about transmission line that I use between my Ham radio and the antenna. We a transmission line that is made of two parallel conductors close together. The current in one conductor is exactly the same as the current in the other conductor, but flowing in opposite direction...

If I shot a 5khz photon at a theoretical antenna made of one copper atom, the electron would absorb the photon and gain energy. What is it about that boost in energy that makes the electron oscillate at 5khz in the direction perpendicular to the photon's direction of propagation?

Hey guys, I am trying to design an Inductive Square Antenna Coil that will be milled onto my PCB. I am slightly confused when it comes to the matching circuit. To my understanding the matching circuit is there to have the same impedance value of the antenna, correct? So my matching circuit...

If you have a classical antenna absorbing an electromagnetic wave, the charged particles inside the antenna will be given momentum in the directions perpendicular to the direction of propagation of the EM wave (because the E and B fields are perpendicular to propagation). If just a single...

I am trying to build my own communication / listening dish, multi frequency antenna, basically my own deep space antenna network. how to get the needed supply for such endeavour? help with any info on this, a new field for me. thanks!

I saw this antenna matrix on the north coast of California this week on vacation (a couple miles north of Half Moon Bay). It's located about 1/4 mile from the beach on Highway 1. There is a powerline running past it, but it looks to just be getting much of its power from a trickle charge from...

Hello Here is an uniform E filed distribution aperture antenna E and H far filed euations and here is directivity calculation approach my problem is why don't we calculate D with both E(theta) and E(phi)? My mean is: instead of using we should use because both of them are not zero in...

As any RF engineer knows the radial antenna is something pure theoretical. But as someone who loves physics an idea came to my mind. Please tell me if this would work and if not, why does it fail to work. So: Assuming we have an atom with 8 valence electrons which is hit with 8 photons with...