What is Antenna engineering: Definition and 16 Discussions

In radio engineering, an antenna or aerial is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver. In transmission, a radio transmitter supplies an electric current to the antenna's terminals, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of a radio wave in order to produce an electric current at its terminals, that is applied to a receiver to be amplified. Antennas are essential components of all radio equipment.
An antenna is an array of conductors (elements), electrically connected to the receiver or transmitter. Antennas can be designed to transmit and receive radio waves in all horizontal directions equally (omnidirectional antennas), or preferentially in a particular direction (directional, or high-gain, or “beam” antennas). An antenna may include components not connected to the transmitter, parabolic reflectors, horns, or parasitic elements, which serve to direct the radio waves into a beam or other desired radiation pattern.
The first antennas were built in 1888 by German physicist Heinrich Hertz in his pioneering experiments to prove the existence of waves predicted by the electromagnetic theory of James Clerk Maxwell. Hertz placed dipole antennas at the focal point of parabolic reflectors for both transmitting and receiving. Starting in 1895, Guglielmo Marconi began development of antennas practical for long-distance, wireless telegraphy, for which he received a Nobel Prize.

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  1. T

    Impedance Matching when the Transmitter, Line and Load impedances are different

    Assume we have a general rf system where source with impedance ##Z_S## transfers a signal to a load with impedance ##Z_L## through a transmission line with impedance ##Z_T##. We want to match this system in order to maximize it's effiency: In https://en.wikipedia.org/wiki/Impedance_matching...
  2. A

    Engineering Noise Floor/Device Temperature Problem

    Hi everyone, I would like to get some help with the following problem. I'm not sure if my answer is feasible. Thanks. My attempt at a solution: I used the noise power equation: Pn= 10*log10(kTB) and converted the -100 dBm to dBW by subtracting 30 dB to get -130 dBW. Then I tried to find the...
  3. A

    How Does Frequency Affect C/N in Dish Antennas?

    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)...
  4. C

    Is it possible to make a passive element that doesn't reemit EM

    Is it possible (and if so how practical) to overdamp a conductor wire that is many times longer than the wavelength of the incident radiation so that it doesn't reradiate any detectable amount, turning practically all incident radiation into heat?
  5. qnach

    Antenna of this shape? What is the benefit?

    Is there a (dielectric) antenna of this shape ---o---o---o---o--- | | | | ---o---o---o---o--- i.e. a ladder? What is the good for such antennas?
  6. D

    *Very* Small Low Freq Antennas with directivity?

    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...
  7. qnach

    Small Loop Antenna: Understanding Its Design as a Dipole or Monopole

    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?
  8. qnach

    Why are magnetic loops used in amateur 8-shape antennae?

    Over the literatures there are S-shape and 8-shape antennae been discussed. What are the differences? The 8-shape seems to be found in amature using magnetic loop. Why magnetic?
  9. qnach

    Is there an antenna with this shape?

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

    Where Can I Find Books on Shell Dielectric Resonance Antennas?

    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...
  11. qnach

    I Non-conductor made antenna?

    Could an antenna made from a non-conductor or a poor conductor?
  12. Tone L

    Phased array antenna vs single antenna for remote sensing.

    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...
  13. M

    Difference between DC/AC coupling (Antennas)

    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...
  14. C

    Electric field in the vicinity of an antenna

    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...
  15. I

    Antenna theory: needed foundation (online courses?)

    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...
  16. H

    Hi I am Hu, a visiting PhD student in the UofW in kitchener

    Hello, Just a big fan of this forum, where people always bring up interesting questions. And it also helped me a lot in my study of electromagnetic. I got a bachelor degree of mechanical engineering. However, during my post graduate study, I turned out to be a antenna engineer by chance, and...