Questions tagged [em]

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17 views

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 ...
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0answers
35 views

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 ...
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2answers
103 views

How, exactly, does the 'input signal' wave(s) modify the carrier-wave of a radio signal? [closed]

I cannot find a simple (or really, not-so-simple) explanation of how mixing the high-frequency carrier wave with the lower-frequency input signal works... Is it entirely due to constructive and ...
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4answers
46 views

Simulation of 2D vs 3D electromagnetic waves

If you using a simulation tool that allows you to simulate behaviour electromagnetic waves in an environment. What differences are there in terms of doing the simulation in 2D vs 3D? Does doing the ...
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1answer
35 views

Inconsistent performance of circularly polarized antenna

I have a circularly polarized patch antenna for an RFID reader, with a gain of 8dBi and bandwidth from 914MHz to 919MHz and an axial of 0.34dB. I have read that using a CP RFID patch antenna means ...
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0answers
43 views

Are there any general guidelines for knowing which order to find equivalent capacitances/resistances in

When simplifying a circuit with multiple capacitors or resistors is there a generally accepted order for knowing which equivalent capacitors/resistors to find first? Should I start farthest from the ...
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0answers
50 views

Effects of wood on UHF transmission

I have set up the following scenario in gprmax. From the results obtained using the software, I realized that when I increased the wood thickness the power received at the receiver increases instead ...
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3answers
102 views

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 ...
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1answer
36 views

Power received by RFID tag

Power calculation from E and H field Following from the previous post above. The user provided me with some assistance however I am still a bit unclear on how to apply the equations provided. Could ...
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1answer
57 views

Power calculation from E and H field

I am using gprMax to simulate my design. The design is shown in the picture. It consists of an RFID system inside a steel structure. The transmitting antenna is placed in the middle of the container ...
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1answer
48 views

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 ...
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0answers
51 views

Interpretation of data

I hope this question meets the standards of this platform, if not please inform me of how I can improve it. I was trying to design an antenna and I have done so. I am planning on using this antenna ...
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1answer
48 views

Conceptual question about Frii's equation

That's a pretty basic one but for some reason I am stuck now: Suppose I have a transmitter that transmits Ptx=4W_EIRP with an ideal, omni-directional antenna. The power applied to the antenna ...
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0answers
22 views

Difference between a RFID reader's antenna and a conventional antenna

What are the differences between an RFID RHCP patch antenna and a conventional RHCP patch antenna? If there are no differences can I just refer to an RFID reader's antenna as an antenna?
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1answer
110 views

FDTD simulation for beginners using matlab

My previous posts are as follows: 1.Mitigation of dead zones when applying circular polarized antenna 2.Standing waves modes inside a cavity resonator 3.Visual understanding of EM fields within a ...
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2answers
53 views

Why do LF RFID tags use near field and why is reading distance longer with UHF RFID?

Why do LF/HF RFID tags use the near field (magnetic coupling) and not the far field? Well, I guess it's easier. The two antennas can just be modeled as a "transformer" and power transfer is straight ...
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1answer
66 views

Multimode cavity resonator

From my previous posts Insight into cavity resonators, Visual understanding of EM fields within a rectangular metal container I have slowly gained a better insight into cavity resonators and thereof. ...
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2answers
325 views

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 ...
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2answers
352 views

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 ...
5
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3answers
270 views

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 ...
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1answer
38 views

Not full-wave signal transmission?

Is it possible to transmit half-wave signals repetitively, like repetitive "north" magnetic fields like going from 0-1 Gauss "north" and repeat however many times per second without going 0-north-0-...
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1answer
62 views

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?
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1answer
50 views

E fields and M fields in Near Field

I am reading a textbook that mentions that small loops with high dI/dt on a PCB tend to produce predominantly magnetic waves and stubs with high dV/dt tend to produce predominantly electric waves in ...