Hello great researchers,
I am working on a wireless pressure monitoring project where sensing part is actually an LC resonance sensor and I am using a planar coil as a reader to get wireless contact between sensor and reader. Reader coil is connected with a Vector Network Analyzer (VNA) where I am measuring the S11 parameters in log magnitude form. Currently I am able to detect the resonance frequency of the sensor from a distance of 3mm between sensor and reader but I want to increase this distance up to 5-10 cm but I am struggling in this. Can someone help me to find out a solution that how I can increase the coupling range between sensor and reader. I have flexibility at the reader size.
Thanks in advance,
Farooq
Dear Muhammad Farooq ,
What is your operating frequency?
One of the factors that increase the coupling is to direct the access of the two coils to align then to each other. The other factor is to increase the operating frequency such that you enhance the far field component. You increase the turns ratio of the sensing and reading coils.
If this can not help then you can relay on the far field using antenna and low noise amplifier.
Best wishes
Dear Muhammad Farooq ,
What is your operating frequency?
One of the factors that increase the coupling is to direct the access of the two coils to align then to each other. The other factor is to increase the operating frequency such that you enhance the far field component. You increase the turns ratio of the sensing and reading coils.
If this can not help then you can relay on the far field using antenna and low noise amplifier.
Best wishes
Hi Abdelhalim abdelnaby Zekry ,
Really thankful for your answer, Actually I have 2 sets of sensors, one set of sensors works between 30-60 MHz and the other set works between 130-160 MHz. My first choice is to use resonance coupling phenomenon instead of far field. My reader and sensors coils are already being aligned and I am getting good signal until 3 mm but I want to increase this distance up 5-10 cm while using the same resonance phenomenon.
If you are using inductive coupling you can read out to a distance about two or three times the diameter of the biggest of the coils. Sensitivity falls off as at least the cube of distance. Look up application notes for RFID, which give all the equations that you can put in a spreadsheet, a lot of them work this way.
Thank You Malcolm White for your answer. It is very useful for sizing of the such method.
As a proposal I would like to support the inductive coupling with capacitive coupling. You need only to add a metal plate at the end of coils. So, you have in addition to the two coils a pair of plats facing each other.
May be another solution is to install a coil in the mid distance between the sensor and the reader as a a passive repeater station.
Best wishes
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