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32 Threads found on Dielectric Constant fr4
Bad idea. 1. u could not get the exact valune of the dielectric constant of fr4 at 33GHz. 2. At 33GHz, loss tangent of fr4 is very large.
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
Hello vpmedina I think that dielectric constant of a laminate is independent of its thickness. But about fr4, it's produced by various companies in the world. You can find them by googling web, then you can find dielectric constant of their laminates in the datasheets. But as a rough approximation you can (...)
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 (...)