Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [em]

30 questions
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Insight into cavity resonators

Modes of a waveguide As shown in the link above, they show how these modes work for various values of m, n, and p. However, where is the antenna/ source of radiation placed within the cavity? From the picture I have shown the placement of 4 antennas…
JoeyB
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Visual understanding of EM fields within a rectangular metal container

I have the following scenario setup inside a rectangular metal container. The container size is 12.03m by 2.39m by 1.84m (lxbxh). Additionally, inside the container I have placed 4 antennas equally spaced, this is shown using the green squares…
JoeyB
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Distance requirements in antenna arrays?

Antenna array is a broad term and it encompasses at least the following concepts: MIMO or massive MIMO: for spatial multiplexing beamforming: increasing the SNR (at transmitter or receiver) by aligning the signals properly phased array: special…
divB
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How specify rectangle size in Sonnet lite

Although not directly an electronics question, there is probably someone who can help me out. I just started to use Sonnet lite to simulate a microstrip filter. There is one aspect, which to me seems very basic and which I am unable to do. Looked…
Waldorf
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How do I EM-Extract a subcircuit and define a different em/drawing-layer than the original circuit in AWR?

I have a 4-layer project in AWR/MWOffice and have built a parameterized microstrip inductor schematic (named "spiral") with a "Line Type" of layer1 that I wish to reuse on another schematic as a subcircuit (SUBCKT) on layers 1,2,4. When I place…
KJ7LNW
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Using a far field UHF RFID in the near field range

I have a 902 MHz to 928 MHz UHF 8dBi far-field RFID antenna connected to a reader. I want to read RFID tags. What will be the consequences if I used this UHF antenna in the near field range when it is meant to be used in the far-field range? This is…
JoeyB
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Why is a horizontal rod a full wavelength oriented radially to a broadcast antenna not the best receiving antenna

I have always struggled to get a good physical understanding of Electromagnetic waves. I've done the whole Maxwell's equation approach, wrote boundary element solver tool but cannot rationalize that with a phenomenological understanding of E/M. The…
Kevin Buchs
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EM propagation analysis

I have an antenna which runs at 917MHz located inside a metal structure that measures in at 6m long, 2m wide and 1.9m high. The exact location of this antenna will be in the center against the length of the metal structure. I would like to know how…
JoeyB
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Electromagnetic wave equation for GPS waves

Recently, I came across a source which stated the model of a GPS L1 wave was: My question is, how was this equation derived?
Lord Farquaad - E
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Metal detector coil wire gauge

Many designs of metal detector coils use different gauges of wire for the TX and RX coils - why is that? Does the wire thickness influence other parameters rather then just the resistance and current carrying capability?
ron vais
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What is the difference between these two input impedance equations?

I'm currently solving some university E&M homework problems and to solve input impedance, we were given this formula (from Fundamentals of Applied Electromagnetics 6th Ed): But when I browse online on the subject matter, the presented formulas are…
jacob arnold cena
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Does a receiving antenna radiate the power received?

Let's consider the case of linear dipole antenna or Hertz dipole. I know that the antenna acts as a transducer and it radiates the E-M waves due to the acceleration and decelaration of the electrons or charges in the wire. While receiving the…
Moulee
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Question on spark gap transmitter circuit

I am trying to understand how basic electromagnetic communication works. From what I understand, spark-gap transmitters were the first wireless devices made by man. A couple of circuits I found online involve high voltage devices that create a spark…
Mat
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Finding constant in electrostatic equation given only charge

So in a region of free space with zero charge, all I'm given is that the electrostatic potential V is given by: $$V(x,y,z) = kz(x^2) y + 2y - 6y(z^3)$$ [Volts] To find the constant k, would I have to use the assumption that there is zero electric…
swattsen
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Need RF advice (NFC antenna VS GND pour)

I'm currently working on a design who involve a NFC chip (ST24DV) who need to be on the board as it's used to communicate with a smartphone. Here is the picture of the antenna: There is a LED on the right (yellow circle) I can't move due to…
Prof_Sims
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