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32 Threads found on Dielectric Constant fr4
Very bad idea. Also, in addition to the loss tangent, the dielectric constant isn't that well controlled by the manufacturer. Look into using one of Roger's substrates, or even a custom alumina substrate.
I presume the OP knows about the existence of dedicated RF substrates, the loose specification of electrical fr4 parameters and it's relative high dielectric losses at microwave. The losses of fr4 are additionally promoted by the intentional roughness of the copper foils. If fr4 is suitable though for a specific microwave (...)
for a rectifier board, you do not normally need s parameters unless it is a directional coupler. or microwave you need to choose something like GETEK or a low loss fr4 which has a slightly lower dielectric constant. If you have no board layout software, EAGLE is free.
From 0 to 100 Celsius there are just slightly variation of dielectric constant vs temperature:
Er is dependent on the dielectric material used (4.3-4.5 average for fr4 based PCBs. Z0 is dependent on the topology used on a PCB design, number of layers proximity to planes etc etc. Download and play with this:
If the height is small relative to wave length, you can calculate an effective height for the layered dielectricum. e.g. H(eff) = H(fr4)/4.4 + H(airgap)
Hello Colleague, - I found an accurate equation for Zc in the book "Antennas for all applications" by John D. Kraus: Zc= Zo/(√ε r[(W⁄t)+2) 92593 Where: Zc= Characteristic Impedance Zo = Intrinsic impedance = 377Ω ε r = dielectric constant from your material: I guess is fr4. W = widt
PCB dielectric Coefficient for fr4 is not constant by frequency so that the manufacturers give this coeffcient for certain frequency,temperature and relative humidity.Therefore the dielectric coeffcient which you used to calculate characteristic impedance for PCB traces migh not be correct. In additional to, if the operating (...)
I suggest you use GE fr4 called GETEK which has 10x lower loss tangent than most fr4. W I suspect you are using lossy fr4 and also dielectric constants is much lower at 2Ghz since rated parameter . Also dielectric constant drops 10~20% as f goes up. Return loss of thinner (...)
I am making a pcb antenna which has a resonant frequency at 13.56 mhz and which will be etched onto a fr4 substrate These 13MHz "antennas" on PCB are more or less inductors, with inductive near field coupling. They are designed/calculated like other printed regular inductors, and the dielectric constant of the PCB
Hi, I am designing a single rectangular patch antenna . the substrate is fr4 and its dielectric constant is 4.4. I have used Inset feed for the antenna. The frequency is 2.4Ghz. I obtained the following results. My resonant frequency(Rf) is 2.399Ghz return loss @ Rf is 40 db There are many ways to choose the Bandwidth . I (...)
Beware that there are many different suppliers, which are interchanged by the PCB manufacturers frequently for cost reduction. Ans all have different dielectric constant and loss tangent. So in short you can only use fr4 in case you can live with these larger variations by taking it into account during the design phase.
Given your physical length of 77.8 mm and effective dielectric constant of 3.27 (did you use fr4 with er = 4.4?), I would expect the electrical length to be in the range: electrical length = 77.8mm*sqrt(3.27) = 141 mm (above the cut-off frequency). This equals a delay of about 338 degrees at 2 GHz. It will be somewhat more because of (...)
Thanks.... may i get information about practical calibration of dielectric material?
Hi all, My 1 mm fr4 board warps all over the place when heated. Do u know of a cheap PCB substrate with similar dielectric constant to fr4 but is stiffer? Thanks You have to compromise either on the price or the quality. Naturally you cant expect sugar at price of salt. :D Cheers
hi all! is fr4 a standard? i mean if one material is said to be fr4, will other fr4 materials have the same characteristics? also, will the dielectric constant change with the width of the fr4? thanks much vpm
hi there, i need to design a 4 element patch antenna array. i have 6inches (w) by 4inches(h) fr4 board. i need to design the array so that feed network, array and impedeance transformer all fit on the stated board can someone please 1)suggest an appropriate operating frequency for the array 2)tell me the dielectric constant, loss tangent (...)
Hi, I would like to know if a multilayer PCB with a high dielectric constant (e=10) and low losses at high frequencies is possible to manufacture. Thanks a lot.
Depending upon your circuit if only transmission lines are there then fr4 is good it has a dielectric constant of 4.4. RT duroid is much much better but costly. You can simulate the results with both materials and can see the difference which is better for you circuit. Hope it helps
If you're looking for a check list, here's a basic one: 1) Make sure you know the dielectric constant of the board. If you use fr4, and are really high frequency (say 4 GHz) or higher, you may need to design for losses along traces. This is because the dielectric constant of fr4 is only (...)
A slab of PCB material doesn't have a characteristic impedance - a trace etched on the PCB material has a characteristic impedance. The impedance of a trace on a PCB can be measured and is dependendent on the width of the trace, the thickness of the copper used on the trace, the frequency of the applied signal, the dielectric constant of the PCB m
I want to use HFSS to simulate a slot line structure with the fr4 material as a transmission line to get the characteristic impedance and effective dielectric constant. The first question is about the port, should I use the wave port or the lumped port? Well, lumped port is better for the microstrip line structure, for the field is (...)
hi. as i could find out, most of the fr4 manufacturers give the dielectric constant at 1MHz in the datasheets. some of them provide the Er at 1GHz. if my board works on 400MHz (also not exact, because its a digital signal, so it has a spectrum...), then i can only estimate the Er, so my impedances on board will have a big tolerance. (...)
Rogers board are ok for that ,they have stable and constant and unform dielectric across the board. (rogers pcb)
One problem with fr4 is the variation in its dielectric constant from batch to batch. It can vary by at least +/- 0.5. Maybe your antenna design can take this variation. A quick simulation check using the extreme values for the dielectric constant will answer this. If this is acceptable then fine, use (...)
Anyone pls tell me how to find the dielectric constant of an unknown fr4 board using microstrip line... Then if I have a Er =4.7 fr4 board @ 100 MHz ... anyone can tell me how to find the Er of this board at 4 GHz. Thanks.
MAy i know what is the fr4 dielectric constant at 5.8Ghz? Thanks for helping..
dielectric constant vary with diferent manifaturers, but in general is about 3,7-4,7 for FR-4 material. There is special materials with higher ε for special RF proposses. They based on same ceramics matiral and tipicly ε is in region of 9- 10 at the working frequencies. This "higher" dieledtric constant, helps to keep phisical (...)
fr4 is a composite material, in most cases its a good approximation to assume a dielectric constant Er of 4.2 The two main constituents of fr4 are glass with an Er of around 6 and resin with a dielectric constant of around 3. Typically manufacturers quote a dielectric (...)
Prop delay in fr4 material is about 150 Ps/in for microstrip and about 170 Ps/in for stripline with a dielectric constant of about 4.5 if you have a microstrip trace 2 inches long it would be 300 Ps, if the trace then transitions to an inner layer and travels 2 more inches the additional prop delay is 340 Ps, total prop delay = 300+340 or (...)
Why using teflon dielectric instead of fr4 for high-end audio pcb ? any ideas? cheers
fr4 is not a good material to use at 1 GHz. Use high frequency materials that has a more stable dielectric constant with less loss.