Antenna Definition and 418 Threads

Hi all, I'm implementing ray tracing .. If we say that an antenna is linearly vertically polarized, does that mean that the direction of E field emitted from the antenna is vertical with respect to the coordinates of the antenna or vertical with respect to each ray's coordinates? For...

Hi all, Does the antenna gain depend on the angle of the emerging ray? or It can be a single number for all ray emerging in all directions? I know the gain is the amount of power an antenna has relative to an isotropic antenna. Sometimes it means the maximum power an antenna can have relative...

Hello, I got the following problem. 1. Assuming that your cell-phone antenna acts like a monopole, how long should it be if the cell phone operates at a frequency of 1.8 GHz? (Note: 1 GHz = 1000 MHz = 1,000,000,000 Hz.) 2. λ= c/f f would 1/T, T being the Hz. But that would be...

Homework Statement An antenna has a normalised E-filed pattern, En where \theta = vertical angle as measured from z-axis and \phi = azimuth angle measured from x-axis. Calculate the exact directivity En has a non-zero value whenever 0 <= \theta <= \pi and 0 <= \phi <= \pi. Elsewhere, En...

Homework Statement A radio-frequency EM plane wave propagates in the +z-direction. A student finds that her portable radio obtains the best reception of the wave when the antenna is parallel to the x--y plane making an angle of 60 degrees with respect to the y-axis . (a) Consider an instant...

I'm having difficulty visualizing what the output of an antenna looks like. Would someone care to explain? This is where I am stuck. Imagine we have a point source that transmits energy. If at time t0 a pulse occurs which outputs a spherical wave, and some time later (say t1) another pulse...

I've been trying to learn the details of electromagnetic radiation from a hertzian dipole antenna, but all the information that I find only gives me a patchy understanding. This is what I have so far: Near-Field: Charges oscillate past each other in a center-fed hertzian dipole. This...

Connect an antenna with 75Ω line impedance to VNA Hello, how can i connect an antenna with 75Ω line impedance if vna has 50Ω input impedance. thanks

Hi guys, I'm in my final year of my physics degree and for my first semester project I had to make a dipole radio antenna, and it's proven to be quite tricky (at least in the theory side of things). I would seriously appreciate some help with a few things if anyone has anything to offer :)...

I am a self studier. I want to study antenna theory and design. Please give me name of some good books particularly ones have solution manuel available. Thanks

Homework Statement A radar antenna is tracking a satellite orbiting the earth. At a certain time, the radar screen shows the satellite to be 162 km away. The radar antenna is pointing upward at an angle of 62.3 degrees from the ground. Find the x and y component(in km) of the position of...

Hi everyone Currently I am reading through antenna imaging effect. I am aware of positive and negative imagaing (essentially the polarity of the antenna is constant/reversed depending on the antenna orientation) However the illustrative example my lecturer has given me has caused quite a...

Hello guys, i got a task to design the ground station antenna. I need atleast to figure out G/T of the station. I looked at different link budget analysis, but could not find out how to calclate G/T of the antenna, or atleast how to assume this value. Usually G/T is given, but i got inverse...

Homework Statement i need to find emf across 50 ohm load attached to square loop antenna of single turn with each side of 10 cm. this antenna is placed 10 cm away from a similar antenna which is driven by a sinusoidal source of 10 v amplitude and with 1mW power. Homework Equations i...

An antenna behaves like an RCL circuit. The R is the radiation resistance corresponding to energy actually radiate. Half come from the E field and half from the B field. The L and C are responsible for the reactive field close to the antenna. the C tells about the energy stored in the E...

What is it about an antenna that gives rise to a particular polarization? Can antennas have polarizers similar to the ones used in optical systems?

Both my and my wife's car are fairly new. Yet the radios are very bad. In the old days there was some adjustment that could be made called trimming. Does anybody know if there is a procedure for optimizing on todays radios? AM.

I searched the forum and didn't find any input on this subject. Dear PF members, I need your help. I am at training for a university, and am assigned a project where I should design a quad-band (or tri) GSM antenna for a vehicle. I am going to second year EE undergrad. so I am only required...

What are the equations for a phased antenna array due to: 1. Individual element gain and the number of elements 2. Aperture of the array I have been googling these for god knows how long and can't find the slightest hint, except the site Microwaves 101 (http://www.microwaves101.com/)...

Hi I was wondering how can antennas capture + receive Electromagnetic waves I was thinking, in particular of FM Transmitters Antennas, and Fm receiver Antennas. And also, how come metals act as a shield to EM Waves I know that antennas have a resistance, and that they consume Energy by...

i am a third year btech student , i am interested in gaining knowledge about antenna and their working.kindly help me by referring some good books for begineers.

Hey guys, professor at college just completed teaching amplitude modulation and other stuff.Well while explaining need for modulation he said that height of transmitting antenna should be a multiple of "one fourth the wavelength" and so it is required to modulate the signal to higher carrier...

Could someone give me a quick explanation of antenna reciprocity and if/how antenna gain can increase RX sensitivity? Thanks.

In making antennas, the higher the frequency the smaller the length of the antenna. The length of the antenna is somewhat equal to the wavelength. But why? I mean, can't we just grab any piece of metal and put in AC current and there would be EM wave correspond to the AC signal whatever the...

This is a strange experiment (or not so compared to some of the experiments I've done) that I am currently undertaking, and require your help. I have built an interferometer of sorts. Two metal funnels of diameter 200mm are attached together by copper tubing (20mm?) through a Y junction with...

Vector Potential Homework Statement Consider two half wave antennas each ahving current I(z,t)=\hat{z} I_{0}\cos\omega t\sin k(\frac{d}{2}-|z|) where k=\omega/c Each antenna has length d and points in the z direction. Antenna 1 is at (\Delta/2,0,0) and antenna two is at...

How does antenna transmits electromagnetic waves? For example radio antenna. How does the antenna produces moving electromagnetic waves?

[b]1. Homework Statement [/ What is the greatest RMS voltage generated in a circuluar loop antenna which is 30.0 cm in radius (also located 14.0 km away) Homework Equations V=wA The Attempt at a Solution So the frequency is 170MHz. My question is how to deal with the root mean...

the radiation intensity of a dish antenna is supposedly given by K(theta) = blah blah something. I don't understand why the radiation doesn't also vary in rho. Does this mean that the radiation is the same for all rho? I'm having trouble picturing that in my head I guess. Thanks; Sean

Interesting idea about extremely high-frequency light being absorbed by nucleons: http://www.aip.org/pnu/2007/split/837-1.html A new generation of antenna engineering? Could nuclear antennae be used for extremely high bandwidth communication?

Seems to me I was taught in college physics that either a spherical "antenna" could not radiate or an antenna could not radiate spherically. Are either true? How about for an acoustical spherical membrane? For quadrupole mediated gravity?

Consider please a conducting wire located in a plane electromagnetic wave propagating in the positive direction of the OX axis The wire is normal normal to the direction of propagation. Have you seen an expression for the potential difference between the ends of the wire? Thanks in advance for...

hmm just a topic for discussion..im revising for an exam and i found an old paper asking to find rms values of electric field and magnetic field from power...and that's easy, using the poynting vector. Then it asks, given a piece of wire of length l in these fields, you can either use it as a...

Help: antenna -- dBic Hi, I need help. For antenna, what is dBic? What is the relation of dBi and dBic? Thank you!

Homework Statement A car with a vertical radio antenna 85cm long drives due east 25 m/s. The Earth's magnetic field at this location has a magnitude of 5.9 * 10-5 T and points northward, 72 degrees below the horizontal. a) Is the top or the bottom of the antenna at the higher potential? b)...

I am looking for some information on antenna coupling. I am looking at coupling energy from one transmitters antenna into another antenna. Basically instead of using the antenna on the transmitter itself, I need to use the second antenna. This is for a project at work. I designed a second...

Homework Statement A car with a vertical radio antenna 75 cm long drives due west at 23 m/s. The Earth's magnetic field at this location has a magnitude of 5.9 10-5 T and points northward, 74° below the horizontal. Find the induced emf between the ends of the antenna. Homework Equations...

A car with a vertical radio antenna 75 cm long drives due east at 29 m/s. The Earth's magnetic field at this location has a magnitude of 5.9* 10^-5 T and points northward, 72° below the horizontal. (b) Find the induced emf between the ends of the antenna. Relevant Equations: E = BVL...

The broadcast antenna of an Am radio station is located at the edge of town. The station owners would like to beam all of the energy into town and none into the countryside, but a single antenna radiates energy equally in all directions. There are two antennas separated by a distance L. Both...

How does a Radio Antenna Work? I'm trying to get a grasp of the physical mech. You generate an AC signal on a conductor (i.e. at 30mhz) The free electrons on the skin of the conductor osc. back/forth at 30mhz. The acceleration / decleration of the free electrons causes photons to be...

Hello All, I'm wondering if there is some nifty formula out there that will tell me how much wire I will need to wind a loop antenna if I know what the diameter of the loop will be and the frequency that I want to tune into? Thanks, Jason O

So I'm sure you all know that the building Dana lived in in Ghostbusters was built as an antenna for psychokinetic (or whatever) energy, focusing that energy on the 13th floor... Well, I was in a new client's building in Philly a couple of days ago and the facilities guys took us to one...

Hello, This is kind of an odd-ball question. Is there a such thing as a toroidal antenna? If one were to take a toroidal core (non-metal) and wind some wire on it to pickup/transmit at a certain frequency, what would it do? My initial guess is that if it is to be a transmitter, that whatever...

Ok. I'm currently trying to understand antenna strength in the wireless cards you find for your computer. Let's say that I have a wireless http://www.tigerdirect.ca/applications/SearchTools/item-details.asp?EdpNo=706706&Sku=D700-2286" with a certain "receiver sensitivity". How exactly do I read...

Let me rephrase my question here, since some of the responses in the orignal thread arent really what I am after, maybe this is more of a physics question than an electrical engineering one... If we apply a 10 volt peak to peak square wave to an antenna (assume the signal goes from +5 volts...

I was wondering, how come with Satellite TV, I have to have a dish pointed directly at the satellite while with Satellite Radio, I can just have an antenna pointed anywhere in the sky? Is it because satellite radio is at a lower frequency or do they just push out more power?

I am researching radios in physics, and i need to find out what current is induced into a wire depending on its power, i don't know the units for the power of the radio wave. can someone help me out? thanks.

A circular loop of wire can be used as a radio antenna. If an antenna with a diameter of .215 m is located a distance of 2.50 km away from a from a source with a total power of 57.0 kW at a frequency of 102 MHZ, what is the maximum emf induced in the loop? (Assume that the plane of the antenna...

I have 2 horn antennas facing each other each has a size A & B respectively they operate at a frequency 800MHz to 2.5 GHz. they are a distance D apart. when making gain measurments there is a ringing effect which changes as the horns are moved futher or closer apart. Does anyone know if this...

does anyone know about a paper by a guy called Chu in 1948 describing the radiation q of a electrically small antenna. In it he using Hankel functions to describe the radiation wave of a small antenna. I was wondering if there is another other functions that can describe the same process Lisa