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# Fringing

52 Threads found on edaboard.com: Fringing

## Core effective permiability and gapping

The calculation is wrong, either for ideal magnetic circuit model or for real circuit (considering fringing field). As for the ideal calculation, where is core ?r in your formula? Your calculated value gives a correct estimation if ?r >> le/g ?e = le * ?r / (le + g*?r)

## Antenna (bandwidth, Q-factor , permitivity)

This difference in length is due to fringing fields around the antenna, which makes the printed antenna seem longer. For example, when designing a patch antenna its lengths typically are reduced by about 4% to achieve resonance at the desired frequency. With the increase in height of the dielectric material, the fringing fields from the edges incre

## Ansys HFSS - Fringing Field Capacitance

Hello All, I was wondering if someone might be able to help me determine the fringing capacitance due to a parallel plate with an extended dielectric? My test project (attached below) is just a simple two parallel plate setup with a Lumped Port connecting the two at the center of the two square plates. I set the resistance to 1ohm and the rea

## Dielectric permittivity relation to the fringing, radiated power, efficiency.

Hello, What is the relation between the dielectric permittivity and the fringing on the edges of the patch? does this have any relation to the radiated power, the efficiency and the bandwidth? your help is appreciated. Thank you Kawther

## Differing Circuit Models for Cavity Resonators

in your second model, the lumped equivalent circuits shown in the pink box look like the Z1 of the first model. So, to a first order they are the same. I personally think the 2nd model is a little more useful, since it has elements that correspond to the physical reality of a probe coupling. i.e. there will be fringing capacitance to ground, an

## [COVENTOR] Simulation of fringing capacitance

Hello, I am going to simulate a proximity sensor based on measuring fringing capacitance in CoventorWare. However i can't find anywhere if CoventorWare is able to simulate such capacitance, or maybe just the direct one. Thanks for anyone who can anserw my question.

## Step in microstrip lines

In Step Width Junction discontinuities the effect of the fringing capacitance associated with the wider line of the step discontinuity is similar to an increase in the length of that line. The discontinuity capacitance C that appears due to the discontinuity has the effect of an increase in length of the wide line (2.8mm in your case), and an equal

## Microstrips lines radiation loss is bigger for thin or thick lines?

Decreasing the height of the substrate reduce the radiation loses but make the microstrip line thinner, with higher ohmic loss. Increasing the height of the substrate, the fringing fields from the edges increase, make the effective length of the line longer, and the input impedance of the line become slightly more inductive.

## Dipole current distribution and Zin

Not quite. That is contradictory. For a dipole you can choose 1/4, 1/2 and 1 wavelength. Resonance is non reactive just below theoretical due to fringing and thickness. more details here 1/2 wave is most common.

## Is there anybody know what is Cgs_M?

Depending on modeling philosophy (and particularly important to things like RF switches and CMOS PA antenna-matching) the metallization - gate poly fringing capacitance may be separately, specially treated (de-lumped from the gate-source, gate- drain silicon-thinOx-gatePoly plate and fringe) in the layout parasitic extraction and the SPICE / Spectr

## relation between "resonant frequency" and "resonant length"

In a purely theoretical sense, a monopole will be resonant when it is quarterwave, 3/4 wave, 5/4 wave... a dipole will be resonant when it is half wave, full wave, 3/2 wavelength. But in reality, there are feedpoint issues, fringing capacitance issues, non-infinite ground plane issues, nearby objects causing effects (like a human body). So, on

## How fringing field affect current in antenna

well, of course. If you have a microstrip patch antenna, for instance, you must forshorten the patch length x width to compensate for the fringing capacitance along the patch edges. Otherwise it resonates lower in frequency than desired.

## Flyback transformer design

i have a spreadsheet that will tell you the inductance but it won't tell you the increased inductance due to fringing flux and all that. so in practice, you will be building a few prototype transformers and grinding the cores down, then later measuring the gap.

## Effective Dielectric constant of two materials

Hi, The problem is I need to find the surface potential where in the electric fields are elliptic (fringing fields). I tried to find the solution when there were one dielectric by using con-formal mapping technique which i succeeded. But the problem here is there are two dielectrics permittivity of 1 >permittivity of 2. Therefore There is a

## How to find the capacitance of a wire

Somewhere in your PDK docu (e.g. in the "analog characterization" description of your process) you should find metal-to-metal and metal-to-substrate capacitance values for each metal layer. Together with the calculated area of the route - if necessary including its fringing capacitance - you can estimate its total capacitance.

## Ground Vias placed around Signal Vias

There is fringing capacitance where the lead in/lead out line attaches to the via. The via itself is somewhat inductive. So you end up with a lumped element model of a shunt C - series L - shunt C. For lower frequencies (<10 Ghz) the capacitance and inductance is such that at least 2 ground vias are needed to keep the insertion loss low. Up a

## decreasing bottom plate parasitics in MOM capacitors

Almost any oxide cut under the cap will -increase- bottom plate capacitance, by reducing Tox(). However in a non- planarized technology you might be able to -increase- the Tox() by surrounding the cap with rings of poly and metal, making the spin-on-glass "pond up". But then you would pick up these fringing capacitances. A bottom plate that is el

## Why does fringing capacitance increase with frequency?

Someone else asked the same sort of question some time ago on the EDA forums, when his simulations with Sonnet showed an increasing capacitance with frequency, and he did not know why. Someone posted a PDF for him to read

## Severe nonlinearity of Cds in enhancement HEMT FET?

The Cdg ought to drop for a while as the drain junction pushes back from the gate, but will eventually flatline when the metallization fringing capacitance becomes all that's left. With these FETs perhaps representng different generations, perhaps that corner is just off the chart for the EPC1013, or the device's useful Vds range ends before that

## Specification for APC-7 connector

Does anyone have a specification of the APC-7 connector? I'm wanting the mechanical specifications. My aim is to put a 3D model of an open-circuit APC-7 connector into a 3D EM simulator, find out how the fringing capacitance varies with frequency, then try to work out the coefficients which could be fed into a VNA so this could be used as an op

## How to determine cutoff wavelength for a microstrip transmission line?

Microstrip TL frequency limit is given by the lowest order transverse resonance, which occurs when width of the line (plus fringing field component) approaches a half-wavelength in the dielectric. So for broad bandwidth, have to avoid using wide lines.

## Why is the capacitance between gate and drain is almost zero after pinch off?

The channel is what connects gate plate capacitance to the drain (and source). When the channel goes away only the overlap & fringing capacitance is "hooked up", the rest is returned to body instead of the inversion sheet when not inverted.

## Capacitance calculation between long coplanar thin plates ??

Same formula applies, however you will have to use the common area between the two plates as A and the spacing as d. No, because a considerable part of the capacitance is contributed by the field above and below the plates, that's what we call the fringing field with a regular plate capacitor. There's no simple formula.

## Simulating Parallel Plate Capacitor in HFSS

At 150mm x 150mm sheet size and only 0.1mm (!) distance between the plates, the fringings fields should be small. An estimate of the fringing fields is to increase the plate size by 1/2 dielectric height on each size, so that it would change from 150x150 to an effective 150.1 x 150.1 ---------- Post added at 20:51 ------

## circular disk patch antenna

Do you mean the thickness of copper ? It should as thin as possible. If you meant the thickness of the substrate, it should be as high as possibl ein order to get maxmium fringing/ radiation. See Belanis chap on patch antennas.

## Fringing in CST Microstripes

Is this likely to be the case, with CST not fully accounting for all fringing No. All EM effects (including fringing) are included in the EM solution. However, EM simulators are only as good as the user who creates the model. If the meshing is too coarse, you will see differences. Also, the material properties mi

## Why thick substrate results in broad impedance bandwidth?

With the increase in height, the fringing fields from the edges (which makes printed antenna to radiate) increase, but also they are reflected, refracted and scattered in a different manner, which affect the bandwidth.

## how to calculate the capacitance between the two lines?

Due to the fringing field, this is not trivial. I do not know if a numerical solution also helps? You can calculate this with the free TNT/MMTL field solver.

## Coupled line filter ADS simulation.

Reduce the coupler lengths. this is to account the edge fringing caps.

## Edge (fringing) capacitance in Sonnet and Momentum

Hello alexneverhurts, You should get the accurate fringing capacitance values from Sonnet, have you subsectioned the structure properly & entered correct values of Metal, Dielectric layer properties... upload your sonnet project file (*.son), we can suggest you by looking into the model... ---manju---

## Gate Voltage threshold and fringing effects

As the gate length becomes very narrow, the fringed electric field area along the edges of the gate (at the source and drain) become the majority of the electric field between the gate and channel. The level 1 mosfet model used to do hand calculation does not account for the fringing effects, it assumes the electric field is straight up and down be

## patch antenna tuning using varactor diode

In second case you short to ground the fringing fields from the edge of the patch element. In a Patch Antenna the surface conductor element does not form the radiating element, as in other antennas (dipole, monopole, etc). The radiation occurs from along edges (Length and Width), and which edge depends by the operating electromagnetic mode.

## How thick is the ground plane of patch antenna?

- With the increase in height, the fringing fields from the edges increase, this increases the extension in effective patch length, however decreasing the resonance frequency. -The Bandwidth of the patch antenna increases with height. -Generally, the patch antenna efficiency increases with an increase in the substrate thickness initially due to t

Using different Er for substrate will affect the Frequency Bandwidth and not the Radiation Beamwidth. One way to change slightly the Radiation Beamwidth is to use fringing shape at the edge of the patch, or fringing-shape for the ground-plane if this one is small (if it has the same dimension as the active element).

## Why the fringing field is bended at the edge of the microstrip antenna?

Hi, fringing fields are always due to the fringing effects and it is always bended. It is like the coupling fields between two microstrips. It is something like that always exists and you can not answer why it exits!!!! But it is there and it does all the magic. Also, the better way of explanation is electromagnetic lines extend circularly

## Fringing Field And Effective Dielectric Constant

Why fringing field of the microstrip antenna is bent at the edge of the patch and from where the concept of the effective dielectric constant came????????

## How to size nmos and Pmos to achieve greater threshold voltage?

Actually, threshold voltage may be affected by narrow-width and narrow-length effects. For short channels, the threshold voltage is reduced due to reduced gate control because of the proximity of the S/D regions to the channel. For narrow channels, threshold voltage increases due to the fact that the fringing fields from the gate raises the surf

## When do we draw NFET on the p-well and when on the n-well in the layout?

An NFET in an NWELL is used to have Capacitors in the layouts. Such MOSCAPS are used because the have less fringing effects and also high Cap when compared to an MIM cap --cmos_dude

## Problem with measuring the inductor area in PCB inductor

Yes, there are too many parasitic capacitance/inductance from the the dark blue color metal plates (fringing capacitance to your ustripe pads, long via inductance). I will guess this piece of metal plate is for shielding purpose, am I right? From the observation of structure of your inductor, this metal plate will significantly reduce the inductanc

## How to design layout for BJT transistor?

Like to other two contributors said, follow the design rules. Typical electrode configuration is C-E-B because you can put the base electrode over the outside isolation thus minimizing your collector-substrate capacitance. In addition, keeping the base electrode away from your collector will also eliminate fringing capacitance to the two electrod

this kind of antenna is based on microstrip line and uses the fringing effect as a radiation mechanism. you should open an antenna boolk (balanis, pozar) for more detailed explanation, or google it :-)

## What's better: one big capacitor or series of smaller ones of the same value?

If it is just one capacitor that you must create, then I think is equivalent. The only concern there is the access resistance. By dividing the capacitor into several smaller ones, you can improve the series resistance and then the bandwidth of the capacitor. Smaller capacitors increase the perimeter/area ratio. Additionaly the fringing capacitan

## MIM capacitor modelling?

Is MIM scaling capacitor model suitable for small capacitor?At what condition the fringing capacitor is not negligible?

## Will the capacitance increase because of fringing effect in parallel plate capacitor?

In general, the effects of fringing for parallel plate capacitors can be neglected as long as both the width and height of the capacitor are significantly larger then the plate separation, a condition that is easily achieved here. However, the presence of etch holes contributes additional fringing that will a

## VIA AROUND A PCB BOARD edge...why?

They call them stitching vias and they are put in to improve the coupling between the ground planes. It helps for EMC compliance, stops fringing efects at the board edges?

## Quasi TEM mode and Axial Ratio???

1. basically TEM is one in which both the electric and magnetic components are perpendicular to each other. but in this case in addition to the perpendicular electric component , there are something called fringing fields at the edges of the centre strip . but this decays expontentially similar to evanascent fields.......a

## Parallel Plate Capacitor

This is usally the case - top plate is gate material, and bottom plate is the mosfet tub which is always bigger than the top plate.. You can estimate it simply by using just the area of the gate region, or if you want to get fancy, you can include the fringing capacitance around the periphery of the gate region.

## How to determine the length and width of the HFSS wave port?

Hi, please refer to the posts in the Electromagnetic Software forum. Waveport size is crucial and would change from structure to structure. If the port is too large, it faciliates the propagation of higher order modes which produces inaccuracies. Smaller port would also result in incorrect answers due to fringing of fields. So you have to o

## About the reflection of two coaxial transmission line

Beacause there is a step in the center conductor, there is a fringing electric field that looks like a capacitance from the center conductor to ground. Because the center conductor current is impeded going from the bigger to the smaller diameter, it acts like a series inductance. So the classic model for such a step in diameter is a shunt capacit

## Ground size of Antenna

but i met some cases in the design of chip antenna always depends on so big Non-GND area around the antenna. Why ? These chips are patch antennas. The fringing fields at the edges of the patch do the radiating. The bottom layer (ground) does not have to extend that far beyond the top layer (patch) for all of the fring