Dielectric measurement method for water using FSMM - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues - primarily having to spend time purging garbage posts from the board. At some point I might start the RF Cafe Forums again if the phpBB software gets better at filtering spam.

Below are the old forum threads, including responses to the original posts.

-- Amateur Radio
-- Anecdotes, Gripes & Humor
-- Antennas
-- CAE, CAD, & Software
-- Circuits & Components
-- Employment & Interviews

-- Miscellany
-- Swap Shop
-- Systems
-- Test & Measurement
-- Webmaster

elia_lyza

Post subject: Dielectric measurement method for water using FSMM

Posted: Thu Dec 18, 2008 11:56 pm

Lieutenant

Joined: Thu Dec 18, 2008 10:56 pm
Posts: 4
Location: shah alam,selangor

For dielectric measurement method for water using Free Space Microwave Measurement system (Microwave Non destructive Testing);

how to calculate/design the container of the sample holder for the water sample..the container was made by plexiglass.

if there are 3 types of water that will be used, then 7 samples of each types of water will be tested, is that possible to use only 3 container of sample holder?

nubbage

Post subject:

Posted: Fri Dec 19, 2008 12:14 pm

General

Joined: Fri Feb 17, 2006 12:07 pm
Posts: 268
Location: London UK

Hi
It is not clear from your brief description how, and at what frequency, you are intending to do these tests.
Assuming you are using an open top plexiglass tank and measuring the Brewster angle, you will certainly need good microwave absorber to ensure a good depth of null as the Brewster Angle is reached. I only ever did water measurements in a closed transmission line/waveguide setup, but a colleague at Uni had endless problems with spurious reflections at X Band using an open radiator free space method, until we found good RAM absorber.
Three tanks should be OK, but you will need to rinse them out for each measurement to avoid any contaminant film across the top surface.
But maybe I don't understand your setup clearly enough.

elia_lyza

Post subject: Frequency range that will be used is 12GHz to 18 GHz

Posted: Wed Dec 24, 2008 3:17 am

Lieutenant

Joined: Thu Dec 18, 2008 10:56 pm
Posts: 4
Location: shah alam,selangor

thank you for your explanation.
i will use the open top plexiglass tank. i want to measure the dielectric constant of the water samples at frequency of 12GHz to 18GHz (Ku Band). i will compute the complex permittivity of the sample from measuring the reflection coefficient (S11) and transmission coefficient (S21).

from the last question that i posted, i will use the free space measurement system. some of the equipments that involves including the Gaussian Optic Lens (GOA) and the Vector network Analyzer (VNA).

Posted 11/12/2012

Webmaster:

Kirt Blattenberger,

BSEE - KB3UON

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website: AirplanesAndRockets.com

My Daughter's Website: EquineKingdom