Rfid tag antenna design for moisture sensor

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hi this is vebi , i want to design rfid tag antenna with moisture sensor can any body suggest me how to design
 
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berkeman

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hi this is vebi , i want to design rfid tag antenna with moisture sensor can any body suggest me how to design
Welcome to the PF.

Have a read through this introductory article, and let us know if you have specific questions in the article.

http://en.wikipedia.org/wiki/Rfid

.
 

dlgoff

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Welcome to the PF.

Have a read through this introductory article, and let us know if you have specific questions in the article.

http://en.wikipedia.org/wiki/Rfid

.
This wiki link is packed full of good information. From it, I checked one of their references on the subject for humidity and did a "Google Scholar" search, and found this paper if you have access to IEEE material.

Abstract

The paper presents a concept where pairs of ordinary RFID tags are exploited for use as remotely read moisture sensors. The pair of tags is incorporated into one label where one of the tags is embedded in a moisture absorbent material and the other is left open. In a humid environment the moisture concentration is higher in the absorbent material than the surrounding environment which causes degradation to the embedded tag's antenna in terms of dielectric losses and change of input impedance. The level of relative humidity or the amount of water in the absorbent material is determined for a passive RFID system by comparing the difference in RFID reader output power required to power up respectively the open and embedded tag. It is similarly shown how the backscattered signal strength of a semi-active RFID system is proportional to the relative humidity and amount of water in the absorbent material. Typical applications include moisture detection in buildings, especially from leaking water pipe connections hidden beyond walls. Presented solution has a cost comparable to ordinary RFID tags, and the passive system also has infinite life time since no internal power supply is needed. The concept is characterized for two commercial RFID systems, one passive operating at 868 MHz and one semi-active operating at 2.45 GHz.
http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=4388398"
 
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thank you for replying, but i read that ieee paper already but i am searching for design specifications of tag antenna i mean the length should be like this or imepedence should be like this my chip impedence is 25-110j i have to design my tag antenna must be 25+110j to transfer total power but i need at what specification can i match chip impedence and for designing antenna with aluminum wire how much length i need or antenna shape either diople or somthing like that........
 
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berkeman

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thank you for replying, but i read that ieee paper already but i am searching for design specifications of tag antenna i mean the length should be like this or imepedence should be like this my chip impedence is 25-110j i have to design my tag antenna must be 25+110j to transfer total power but i need at what specification can i match chip impedence and for designing antenna with aluminum wire how much length i need or antenna shape either diople or somthing like that........
What antenna design experience do you have so far? What antenna design books have you read, and what antenna design software do you have available?

What chip are you using? Why is its input impedance so strange? I would have expected a different input impedance.

What course is this for? What level in school?
 
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i am doing masters,i studied this book rf in uhf rfid book by denial.dobkin but i am doing project on differential rfid sensor design and characteristics but this is my starting of project still my supervisor dint provide any software for simulation may be i will get this week. then i will post all things still now he said that design two antennas one with senor and another without sensor on same tag so i cheked the impedence of given chip by using smith chart analysis then i posted any suggestions on design of antenna.
 

berkeman

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5,151
i am doing masters,i studied this book rf in uhf rfid book by denial.dobkin but i am doing project on differential rfid sensor design and characteristics but this is my starting of project still my supervisor dint provide any software for simulation may be i will get this week. then i will post all things still now he said that design two antennas one with senor and another without sensor on same tag so i cheked the impedence of given chip by using smith chart analysis then i posted any suggestions on design of antenna.
I will ask again. What chip are you using? Can you post a link to the datasheet?
 
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hi berkeman,
i get a warning from physicsforums but i didnt understand that problem please can you give me any suggestion what i have to do and how can i overcome. now comming to the design i used rfid chip from alien technology and the name is higgs 2. you can chek data sheet in below link.
http://www.alientechnology.com/docs/products/DS_H2.pdf [Broken]. now i have to design rfid tag antenna for temperature and moisture mesurement.can you suggest me which sensor is best for application and also can i use resistive sensor for temperature measurement what range of resistor value can i use. how can i achive read range maximum.
if any mistakes is there please forgive me for this time.
 
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hi berkman,
Both temperature and moisture sensors in diffrent tags not in the same tag. for temperature i have to design one rfid tag antenna and moisture measurement i have to design another rfid tag antenna.
 
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so please can you reply me. can you help me...............
 

berkeman

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hi berkman,
Both temperature and moisture sensors in diffrent tags not in the same tag. for temperature i have to design one rfid tag antenna and moisture measurement i have to design another rfid tag antenna.
Can you show us your work so far? What antenna designs have you looked at using? What do your sensing circuits look like so far?

We do not do your school project work for you here at the PF. You need to show us your design work, so that we can comment on it.
 
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hi berkeman,
my project is diffrential rfid sensor design and charecterization. still now i desined just normal tag antenna for that i used dipole antenna in that one is without sensor and another is with sensor in same tag you can see my attached doucument figure 2. to achive better read range and and also to measure physical quantity. i am asking which range of resistor is better to mesure temperature or any other componets is there for suitable application here to measure temperature and moisture.i need best sensors for those two physical quantitys.i will design my antenna with given specification just i am asking diffrent sensor componets in place of resistor (see in fig 2 attached document).which component is suitable for moisture measurement and temperature mesurment.
thank you.
 

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