How to measure dielectric constant of a PCB

pcb dielectric constant;

I am developing an antenna for Zigbee application (2.4 GHz ISM Band). To do a PCB patch antenna I need to find the dielectric constant of the PCB. I don't have any specifications of the PCB. I am wondering how to find the dielectric constant (possibly using an LCR meter). The LCR meter in our lab doesn't give it directly. Can someone please give some guidence on it to me.

In one of the application notes at Chipcon (I'm using one of their transceivers), they have used a folded dipole PCB antenna. Do I need a ground plane if I use that? Is there anyway to check the antenna without integrating to the transceiver. The transceiver has to be surface mount.

I'm a bit new to PCB antenna design and would be glad of any help and direction to some simple design instructions.

Thank you.

+resonator +pcb +material +constant

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measuring dielectric constant

what if you measure capacitance of the PCB? then you can extract the dielectric constant from the formula for capacitance C = εoεr*S/T

D.

measure resonance of pcb

Hi,

Dielectric constant is depending on your operating frequency. A more accurate value of εr is determined by measuring the actual propagation delay of a signal in a trace using Time Domain Reflectometer with unit of inches/ns or ps/inch.

For example at 10MHz the average εr value of FR-4 material is 4.6 and will drop to 4.1 at 1GHz.

You may refer to IPC-2141 for the source and reference.


Goodluck...

measure dielectric constant

agilent has the instruments for dielectric measurement:|

measuring er pcb

I tried to measure the dielectric constant of FR4 with VNA and a piece of dilectric measuring resonance across the following formula:
fmn^2=c^2/er *((n/2L)^2 + (m/2W)^2)

I measured the resonance frecuencies but i don´t know how I get the
integer values of m y n, because I dont know to what fmn correspond

I measured a square 10 *10 cm^2 with 1.55 dielectric height and two copper layer of 0.025 mm height.

I wonder if someone can help me.
Thanks

how to measure the dielectric constant

How do you measure the capacitance ? What instrument do you use?

I wonder if help me
Thanks

dkace said:

what if you measure capacitance of the PCB? then you can extract the dielectric constant from the formula for capacitance C = εoεr*S/T

D.

Click to expand...

measuring dielectric constant pcb

Hi y'all,

one method that I have found to be quite effective in characterizing the properties of some given PCB material is the following:

1. design a ring resonator (length should be an integer multiple of the wavelength that you're designing for, transmission line coupled in parallel with the ring) using some approximate value for εr

2. fabricate the ring resonator and measure S21 with a VNA.

3. resimulate the ring resonator design with same simulator that you're intending to use for your antenna design

4. adjust εr and tanδ of the substrate model in the simulator until the dips and the slope of S21 matches the measured one.

I used this method in characterizing FR4 material at 10 GHz for patch antennas and got good results.

Hope this helps...

dielectric constant used in pcbs in pdf

be careful to measure the Er at the operating frequency.
I have a problem with my project, I had the Er at some other frequency and operate at another one, so I got wrong answers. but you can see the datasheet of commercial company

or

do as the above replies mentioned and I don't mention again.

They are quite well.

Cheers.