Questions tagged [dielectric]
A dielectric is an insulator that can be polarized by applying an electric field. A common example is the use of a dielectric within a capacitor between the metallic plates to increase the surface charge.
114
questions
1
vote
1
answer
48
views
A basic question about using dielectric material in PCB boards in relation to electric field
I was wondering what the PCB's dielectric material(such as FR-4) do to the electric field.
If I'm not wrong, the dielectric material influences how the electric field lines are distributed. And it ...
- 1,791
1
vote
1
answer
223
views
Food for thought: Which person has truth in this discussion on capacity and AC? [closed]
I have stumbled upon interesting discussion in the commentary section regarding safety of electrical engineering in home environment.
person1: AC voltage 'flows' even through insulator, fact.
person2:...
1
vote
2
answers
62
views
Should reference plane change its potential value if a track goes to another layer?
Assume you have a four layer board.
Signal
GND
Dielectric
VDD
Signal
And you having a track in the 4:th layer. Suddenly you're using a via to go through the 4:th layer to 1:st layer.
Question
The ...
- 1,324
1
vote
4
answers
105
views
Determine dielectric constant of unknown FR4 substrate
I have a piece of single sided FR4 PCB substrate that I need to build a 2.4 GHz patch antenna on using copper tape.
Other than the dimensions and it being FR4 I know nothing about the substrate.
Is ...
- 868
4
votes
3
answers
673
views
PCB material with high dielectric constant
Typical PCBs have a dielectric with a low constant \$\varepsilon_r\$. I'm studying the effect the electrical fields on dielectrics and as an experiment would like to test PCBs with a very high ...
- 95
0
votes
1
answer
78
views
Hipot arcing for AC and DC hipot test
I have a substrate with multiple conductor traces (0.5mm gap from each other) with aluminum plate on top used as electrode. The aluminum plate is connected to the hipot "line" and the ...
- 19
0
votes
0
answers
26
views
How to measure the electrical properties to ensure the performance of a thin electrode/insulator stack-up?
I am a mechanical engineer by trade, and I am looking at some basic electrical properties that I need to measure to ensure the device meets the desired performance.
The device consists of a two-layer ...
1
vote
2
answers
679
views
Effective dielectric constant in multilayer PCB design
Top => copper
PP1 => RO4350B
L2 => copper
PP2 => FR4
L3 => copper
PP3 => 185HR
L4 => copper
This is my PCB stackup.
In the top layer, I have a 50 Ω controlled RF trace. The ...
- 11
0
votes
1
answer
79
views
Hipot results vs surface area
I trying to hipot test a 12"x12" metal with kapton layer. Different sizes of metal (e.g. 1"x1", 4"x4", banana plug) is placed on top of kapton tape. The bigger metal ...
- 19
0
votes
0
answers
34
views
Arc-shape frequency dependence of phase angle in bioimpedance spectroscopy
I have concerned myself with bioimpedance spectroscopy (BIS) from a medical standpoint for some time now, however there is one concept evading my grasp until now:
When measuring complex impedance of ...
2
votes
1
answer
172
views
Trying to make a HASEL actuator
I was told that if I apply high voltage to a zip lock bag filled with baby oil with tin foil paper on the end it'd make it contract and act as a HASEL actuator.
I'm afraid of measuring the exact ...
- 35
8
votes
3
answers
1k
views
Voltage required for a spark plug - dielectric constant of air
The dielectric constant of air is approximately 3 kV/mm. The typical space between car spark plugs is between 0.6 and 1.8 mm. By multiplying those numbers in mm by the dielectric constant of air, we ...
- 183
1
vote
1
answer
131
views
Dielectric strength test voltage
I am preparing an insulation diagram prior to testing a device against IEC 60601-1.
How do I determine the dielectric strength test voltage? I couldn't find anything in -1.
- 31
0
votes
1
answer
193
views
Why do material makers call the dielectric constant "Dk" rather than "D.c."?
Why do material makers call the dielectric constant "Dk" rather than "D.c."? Is it kind of German? Something like Dielektrische Konstante? It is actually called a ...
- 121
0
votes
0
answers
121
views
DC hipot leakage current
I noticed that when testing hipot in DC I always get leakage current, but not during AC hipot testing. Do you have any ideas about this? My hipot tester is Quadtech Sentry 500VA. I’m testing a ...
- 19
0
votes
2
answers
156
views
Would an inductor work differently under a different dielectric environment?
I am talking about these common rounded inductors with a metal core that you would find on PCBs.
Would the operation be different in, say, mineral oil vs. air? These are two different dielectric ...
- 749
3
votes
1
answer
606
views
How does selecting a higher permittivity substrate in patch antenna reduce its size?
By selecting a higher permittivity substrate do we reduce the height of the antenna or we reduce the length of the patch antenna? We cannot reduce the length of the antenna as it is dependent on the ...
0
votes
1
answer
137
views
Relays: What is High Contact Stability?
This TE RF relay datasheet shows the component coming in three varieties:
High Dielectric
High Contact Stability
High Current
So high-current is obvious (right?), and (correct me if I'm wrong) high ...
- 2,098
2
votes
1
answer
197
views
Why do dielectric waveguides support hybrid modes and metallic waveguides do not?
Can anyone explain to me qualitatively why dielectric waveguides (core and infinite cladding) support hybrid modes (E_z and H_z components in the guided wave), while metallic waveguides cannot?
I am ...
1
vote
1
answer
129
views
The field in a waveguide at exactly the cut-off frequency
Can anyone explain to me qualitatively, what kind of field exists inside a waveguide at EXACTLY the cut-off frequency?
I would be grateful if an explanation was given about waveguides with metalic ...
1
vote
2
answers
85
views
How to increase efficiency of antenna without moving antenna far from tree?
I have designed a monopole antenna at 868MHz frequency. Now I would like to attach that antenna to the tree (wood). But, due to Why does placing an antenna far from the wood increase the efficiency of ...
- 27
1
vote
1
answer
179
views
Why does placing an antenna far from the wood increase the efficiency of the antenna?
I designed a monopole antenna at 868MHz frequency. I placed wood as the surrounding material. I noticed that placing the antenna far from the wood increases the efficiency of the antenna. Can anyone ...
- 27
0
votes
1
answer
423
views
Dielectric withstand test of DC powered product
I am trying to figure if our test set-up for dielectric withstand test is correct. There are two versions of the DUT (device under test), an AC powered (typical 85-264 Vrms) and DC powered type (12-...
- 401
0
votes
0
answers
153
views
Ampere's Law with dielectric
I am asked to calculate the magnetic-field-strength and magnetic-flux-density for different regions inside a coaxial-cable. I found Ampere's Law for that, but it uses \$\mu_0\$ , and the coaxial-cable ...
1
vote
3
answers
777
views
Following is an excerpt from a power electronics textbook. Is the statement true?
As far as I know ESR primarily depends on the type of dielectric.
eg: Al electrolytic (higher capacitance value) would have much higher ESR than ceramic (usually lower capacitance value).
Say for ...
- 3,032
2
votes
2
answers
2k
views
Capacitors: voltage-dependent capacitance?
While playing around with a capacitive power supplies, I observed some very weird behavior when passing a 60Hz sinusoidal current through a 1000V disk ceramic capacitor. The voltage curve was very ...
- 1,563
2
votes
2
answers
629
views
How do I calculate the capacitance of a capacitive touch or water sensor?
Sensors like capacitive touch or moisture sensors are simply two traces drawn on a PCB. For example, you may check the Grove soil moisture sensor. In these types of sensors, the capacitance increases ...
- 2,519
0
votes
1
answer
223
views
Why it can be asserted that the bottom plate takes the highest potential and the top plates takes the lowest of the capacitor?
The ideal parallel capacitor has been filled with 2 dielectrics as shown in the above diagram.
$$ V_{1} :=\text{potential at the top plate} $$
$$ V_{2} :=\text{potential at the bottom plate} $$
$$...
0
votes
0
answers
94
views
When is PCB thermal destruction desirable?
In the Wikipedia page for FR-4, it contains this excerpt:
FR-4 epoxy resin systems typically employ bromine, a halogen, to
facilitate flame-resistant properties in FR-4 glass epoxy laminates.
Some ...
- 2,892
0
votes
1
answer
39
views
Why the euclid distance between the plates of the capacitor has been doubled to find out the capacitance?
I may have been asking of an easy problem.
The problem requires to find out the capacitance.
The ideal capacitor with area of \$S\$ exists and the euclid distance between the plates is \$d\$.
The ...
0
votes
0
answers
59
views
Does supercapacitor electrode need dielectric layer?
I am trying to build a super capacitor. I use Activated Carbon with Wood Glue, aluminium tin can as electrode, multi layers of tissue paper as separator, and table salt water as electrolyte.
No matter ...
- 477
0
votes
1
answer
703
views
Characteristic Impedance of Multi-Dielectric Coplanar Waveguide
Background
I've calculated the characteristic impedance of a CoPlanar Wave Guide (CPWG) type transmission line on my 8-layer stack-up between L1 - top layer and L2 - GND1 directly underneath it. The ...
- 904
0
votes
1
answer
546
views
Refractive index, wavenumber, and wave impedance of the PEC that a plane wave is normally incident on
I am trying to find the refractive index \$n_t\$, wavenumber \$k_t\$, and wave impedance \$\eta_t\$ of a perfect electric conducting medium t. Here is my work so far:
The conductivity of the PEC is \$...
- 177
1
vote
1
answer
189
views
Impedance of an embedded microstrip with different sub- and superstrate
I have been trying to find a formula to calculate the impedance of an embedded microstrip where the substrate has a different dielectric constant to the superstrate (so the stack up is conducting ...
- 25
2
votes
2
answers
699
views
How to design an amplifier for a sensing liquid level using capacitive probes?
In this problem I have a capacitor that is submerged in a varying level of dielectric fluid. Therefore, the capacitance varies linearly with the height of the fluid. How should I design a simple op ...
- 23
0
votes
3
answers
225
views
How fast is DC current/voltage?
The standard way to calculate the speed of information (current/voltage, EM wave) through a dielectric medium (like PTFE or fiber) is to determine the relative dielectric constant, and compute the ...
- 101
1
vote
2
answers
143
views
Calculating the permitivity of PCBs
I've read that the permitivity of FR-4 is around 4.5, however I would like to measure the permitivity of an actual double sided copper clad board, the way I am thinking is to measure the thickness of ...
- 2,780
1
vote
1
answer
289
views
Can you use 'Rubber,' Specifically Liquid Electrical Tape Between The Plates of a DIY Capacitor
The above is pretty much all there is to the question. By "can you," I mean will it be properly effective / are there any tips? If not, why? It seems that this ought to work, but I can't ...
- 13
4
votes
0
answers
122
views
Can I calculate minimum rise time of a transmission line if I know the length and the loss tangent?
Overview: I am trying to work out if it's possible to transmit my 1.2Gbps MIPI data down a 600mm long flexible PCB strip. Assuming I have the impedance correct, will the signal still be degraded by ...
- 27.5k
0
votes
1
answer
180
views
BIL, Dielectric Breakdown, Shrink Wrap, and Safety. Is there a resource for this information?
I am currently working with a system that produces high voltage transients for system testing, and have some cables that need to be made/modified to work with some new equipment.
The operating ...
1
vote
1
answer
200
views
What material should I use for the plates of my homemade mica capacitors?
I recently acquired some mica as i want to build my own high voltage (50 kV if possible) capacitors. The problem I am encountering right now is that the surface of such a crystal isn't perfectly flat ...
- 178
1
vote
2
answers
2k
views
What material can I use as a dielectric in my own high voltage capacitors?
I need capacitors rated for 50 kV. Buying them is an option but the ones with appropriate voltage rating I have seen cost more than 50€ which is far too much.
That's why I want to make caps on my own ...
- 178
0
votes
1
answer
393
views
Relation ship between Track width, Impedance, Dielectric and copper thickness
I like to know the relationship between different factors like track width, impedance, dielectric and copper thickness.
After quite a reading I got to know that as the track width of a cline is ...
- 217
3
votes
2
answers
383
views
How come distilled water hasn't replaced transformer oil as a high voltage insulator?
I've noticed that distilled water has an extremely high dielectric straight (65-70 MV/m).
With that considered, how come it isn't used in the place of transformer oil for 10-20 kV applications where ...
user154046
2
votes
1
answer
659
views
PCB Layer Stack Dielectric Constant Math
I have a question reference PCB layer stack and the adding multiple dielectric constants together.
The image and description below should help clarify the question:
The differential pair will be ...
- 101
2
votes
1
answer
219
views
What are the "poles" of a signal (after it's reflected perhaps)
I desire to learn about "estimating the poles of a resonant signal", specifically the complex natural resonance of objects.
However, I don't know what "poles" are. What would you suggest I look up ...
- 55
0
votes
1
answer
137
views
HF characteristics of Liquid Electrical Tape
Some self-wound toroid inductors from a HF-radio kit are sitting a bit too loose on their PCB for my liking; they stand upright and are only held in place by the thin enamel-coated inductor wire that ...
- 382
1
vote
1
answer
108
views
How can the dielectric constant of water be so high but water on electric devices can cause a short circuit? [closed]
Is it only the fact that pure water has a high dielectric constant and non-pure water i.e. the water that usually causes a short circuit is contaminated and it's the contamination mixture in the water ...
- 403
2
votes
1
answer
755
views
C0G vs polypropylene capacitors in signal filtering
Can anybody give me a comprehensive pros and cons list or explanation about the differences between C0G (NP0) ceramic and polypropylene capacitors?
I would like to use them in signal filtering and ...
- 81
1
vote
0
answers
438
views
Grounding polycarbonate or Plexiglas
If a record turntable's base is made from a 2" think piece of acrylic (for instance polycarbonate or Plexiglas) can it be successfully grounded to eliminate any static charge that it would build up in ...
- 11