10-04-2017, 08:47 PM
Around the world, sugarcane is one of the important
commercial crops used to manufacture several types of
sweetener such as white and brown sugar1
. Measuring
sugarcane quality in the field is also important to improve
the current payment system. At present, sugarcane quality
is only randomly sampled and measured at the mills using
sophisticated laboratory equipment. Hence, it is difficult
to ensure growers are appropriately paid for the quality
of their product. The current practice does not strongly
motivate growers to pay more attention to improve the
quality of their product.
India ranks first in the international scenario in
sugar cane cultivation as well as in sugar production, yet
the cost of production of sugar is higher in India. This
is due to relatively lower recoveries of sugar per ton of
cane crushed,more energy consumption and higher
losses of sugar in bagasse, filter cake,and molasses. Sugar
production technologies has undergone aphenomenal
change throughout the world replacing human skills and
Indian Journal of Science and Technology, Vol 7(5), 566 570, May 2014
ISSN (Print) : 0974-6846
ISSN (Online) : 0974-5645
Keywords: Frequency Shift, Microstrip, Moisture Content, Permittivity, Resonator Sensor
conventional or traditional processing methods by automation
. The conventional methods to measure sugar
content in sugar cane are IR method, chemical analysis
and optical methods2 5.These methods are time consuming
and it takes 2 3 hours. Several Research have shown
that spectroscopic methods can be successfully used to
predict quality of sugarcane based on juice samples, but
inadequate sample preparation and mixing with reagents
causes major errors in this method6
.
An alternate to the above stated methods is microwave
method which is fast, accurate and non-destructive.
Microwave dielectric measurement methods generally
fall into two categories: non resonant and resonant methods.
Resonant methods including resonator perturbation
methods have relatively high accuracy than non-resonant
ones. Microwave free space method was adopted for
the measurement of sugar content in sugarcane juice in
which the concentration of sugarcane juice was determined
based on change in the dielectric constant. But
the accuracy was limited because of the formation of air
bubbles in dielectric liquid cell7
. The most common type of sensor used for permittivity measurement is using
microstripline.
In comparison with other structures used for permittivity
measurement such as waveguide cells, resonant
cavities or coaxial probes, the advantages of the micostrip
are small size, simple fabrication and low cost.
The material under test is usually placed on top of the
microstripline and its properties are calculated from the
attenuation and the relative shift in resonant frequency8
.
Microstrip ring resonators are frequently employed in
microwave integrated circuit design. Resonant structures
such as rectangular, square, and circular ring resonators
have been widely studied in oscillators, filters and antennas9
. Microstrip Ring Resonator (MRR) has been reported
as a moisture sensor and for permittivity measurement of
dielectric materials10 12. It exhibits a periodic frequency
response with many well-defined resonance frequencies,
which can be exploited to determine material properties.
In this paper a square ring resonator implemented as
sensor is proposed which occupies comparatively lesser
area than the conventional ring resonator of same electrical
length12. The mechanism adopted for the determination of
permittivity is the relative shift in resonant frequency which
takes place when microwave interacts with the sample.
From the measured shift in resonant frequency for different
modes, the dielectric constant for various quantity of sugar
in a cane juice has been established.
