Basic Microwave Laboratory Report

BASIC MICROWAVE LABORATORY

ELECTROMAGNETICS

GROUP REPORT

Wan Farhana binti Wan Ahmad Zamri Wong Soon Yaw

Rahmat bin Kamba Nadia Listari binti Abdul Rahim

Supervisor: Dr. Asrul Izam

1. AbstractElectromagnetism is the force that causes the interaction between electrically charged particles. The induced charge is exist on the stress film used for packaging, particularly in manufacturing industry. The electronic chip can be damaged by electrostatic charge. This experiment is divided into two cases. Case 1 is Faraday experiment, which measure the electrostatic charge generated on the stress film rubbed with cotton cloth by using Faraday pail and charge sensor. Rubbing condition such as rubbing time, size of stress film and type of rubbing is varied to determine their effect on electrostatic charge generated on the stress film. Men and women frequently faced the problems of hair loss. Therefore, hair fibre is used to overcome hair loss problems. Case 2 of the experiment is hair fibre experiment that analyze the performance of two hair fibre product, namely BioTHIK and Nanogen. The relative permeability of hair fibre is measured by solenoid based experiment and relative permittivity is measured by capacitor cavity based experiment. The effect of permeability and permittivity on the performance of hair product are determined.

2. IntroductionCase 1

Stress film is a transparency film which is made by resin. This film is used for the wrapping of the factory product to prevent the product from damage. Charge accumulated on the surface of the film during handling the product is known as the electrostatic charge. The imbalance charge occurs when there is frictious contact between two materials. When objects are rubbed together, there is friction. This causes the surfaces to interact. One surface gains electrons becoming negatively-charged. Another surface loses electrons becoming positively-charged. This phenomenon is known as triboelectric charging. The amount of induced charge is determined by the triboelectric series in which the further apart they are in the series, the greater will be the amount of charge induced when rub together. When there is a medium for them to discharge, electrostatic discharge will occur.

Figure 1: The electron from material A is transferred to material B after they are rubbed together which produce static electricity

Figure 2: The Triboelectric series.

Electrostatic discharge can change the electrical characteristics of a semiconductor device, degrading or destroying it. Electrostatic discharge also may upset the normal operation of an electronic system, causing equipment malfunction or failure. 

The objective of the case 1 experiment is to determine the relationship between electrostatic charge moving towards stress film and how this electrostatic charge could affect the electronic chip.

Case 2

Hair is a reflection of our identity in the society. Women especially feel that a bad hair day is a bad day. Thus, it is very important to ensure hair always look good throughout the day. Nevertheless, hair loss has become a common issue and it is happen to either men or women. There are a lot of causes of hair loss such as age, lack of vitamins and minerals. Nowadays, hair regrow treatment are very expensive and time consuming until the application of hair fiber on the existing real hair is proposed. Within 30 seconds, the hair fiber can conceal the hair loss which make your hair look thicker. Based on the electrostatic principle, the fiber will be tied to every existing individual strand of hair which can results more voluminous hair.

In the market, there are numbers of hair fiber brands. However, those products have set their own properties. The performance of hair fiber depends on the charge density which allows the fiber to be attached to the real human hair. The surrounding environmental condition and the fiber conditions can also directly affect the total charge in the fiber. By shaking the fiber in the container before apply the hair fiber, the amount of charges on fiber can increased.

For this experiment, two types of hair fiber, BioTHIK and Nanogen, are selected to investigate and identify their electrostatic properties, charge density and dielectric permittivity.

3. Methodology

Case 1

Figure 3: Set-up of case 1 experiment

For case 1 experiment, the electrostatic charge generated on the stress film was measured. Faraday Pail, Faraday Cage, stress film, charge sensor, LabQuest, cotton cloth, ground plate, grounding wrist strap and proof plane were the apparatus needed in case 1 experiment. The apparatus was set up as shown in Figure 3. The Faraday Cage and the grounding strip were connected to the grounding plate to prevent the influence of charge. A piece of 3cm x 6cm stress film was rubbed with cotton cloth for 20s. After the stress film was rubbed, the stress film must be placed into inside the Faraday Pail immediately. This was done to avoid the charge generated on the stress film from being affected by the surrounding charge. The amount of charge on the rubbed stress film was measured and recorded by using charge sensor and LabQuest. The steps were repeated for 40s, 60s and 80s, 100s and 120s respectively by using the same stress film. The person that rubbed the stress film and the person that wear a grounding strip must be different person.

After that, case 1 experiment was continued. A piece of stress film with size 3cm x 6cm was rubbed with cotton cloth for 20s. The amount of charge on stress film was measured and recorded. The steps were repeated by using stress film with size, 4cm x 8cm and 5cm x 10cm.

Then, case 1 experiment was conducted with different type of rubbing. A piece of stress film with size 3cm x 6cm was rubbed with cotton cloth softly for 20s. The amount of charge on stress film was measured and recorded. The steps were repeated by rubbing the stress film moderately and harshly.

Case 2(a) Measurement of relative permittivity

From the experiment, the voltage between the two metal plates, V and the capacitance, C will be obtained using multimeter to further calculate total charges on the hair fiber. To calculate charges, the relationship between total charges, Q, voltage, V and capacitance, C is given as below:

Q=V ×C

where Q is the total charges, V is the voltage and C is the capacitance.

As the higher value of the capacitance of the dielectric (hair fiber) can able to accumulate more charges. Next, to further investigate the ability of hair fiber in the real life application, we need to identify the relative permittivity also known as dielectric constant of the hair fiber. Below are the relationship between capacitance, C and the dielectric constant:

C=ε Ad

ε=ε 0 εr

C=ε0 εr A

d

where ε 0 is the absolute permittivity, A is the area of the metal plant and d is the diameter of the capacitor.

The relationship showed that the higher dielectric constant of the hair fiber can contribute to higher capacitance value thus make the hair fiber can store more charges. Thus, in this experiment, to obtain the relative permittivity,ε r of the hair fiber, the formula as below will be applied:

ε r=C sample

C empty

where the C sampleis the fiber sample-filled measured capacitance and C empty is the empty filled measured capacitance.

Next, volume charge density of the hair fiber is also important to identify the quality of the hair fiber. The formula for volume charge density is shown as below:

ρ v=QV

where Q is the total accumulated charges and V is the volume of the capacitor.

Hair fiber with larger volume charge density can store more charges can thus have a better performance.

Figure 4: Hair fiber experiment (permittivity)

The apparatus for hair fiber experiment (permittivity) are:1. Fluke digital multi-meter (Fluke 19B)2. Capacitor cavity3. Hair fiber (BioTHIK and Nanogen)4. Test Probe

Below are steps of this experiment:1. The apparatus were set up as shown in Figure 4.2. The empty capacitor cavity was tighten with screw.3. The value of capacitance and DC voltage were taken after 15 minutes and tabulated in a

table.4. Next, the capacity cavity was opened by loosening the screw.5. The sample holder of the capacitor cavity was filled up with BioTHIK and the capacitor

cavity then enclosed tightly.6. The sensor was filled with BioTHIK hair fiber and connected to the Fluke digital multi-

meter by using test probe.7. Step 3 was repeated.8. The dielectric permittivity of BioTHIK hair fiber was calculated.9. The experiment was repeated by replacing BioTHIK with Nanogen.

Fluke 289 multi-Fluke 19B

Test ProbCapacitor Cavity

Case 2(b) Measurement of relative permeability

Figure 5: Set up of experiment to measure relative permeability of hair fiber

Figure 5 above illustrate the set up of experiment to measure the relative permeability of different hair fiber which are BioTHIK and Nanogen and iron powder as the material used inside the core.

DC power supply is set to 5V and is used to vary the current flow. The number of turns of coils N and the length of each solenoid L are recorded. The solenoid is placed vertically and the vernier magnetic field sensor is put on the top the the solenoid along the axis. Data is collected using LabQuest. The experiments are repeated by varying the current I flow to the solenoid from 0.5A to 3.0A and the magnetic field B value are recorded. Graphs of B against I are plotted for each type of solenoid core to obtain the permeability value.

Permeability can be calculated using the following formula:

Since where

4. Results And Discussion

Case 1

Experiment A: Different rubbing time with the same size 3x6 cm

Table 1 Effect of rubbing time on the value of the charge of the stress film

Rubbing time (s)

20 40 60 80 100 120

Charge of the stress film (nC) -2.2250 -3.1540 -3.5580 -2.8860 -3.6680 -3.7750

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

Figure 6: Graph of Effect of rubbing time on the value of the charge of the stress film

From case A of the experiment, we found out that rubbing time can affect the charge induced of the stress film. This can be proved by the result obtained above. When the rubbing time increases, the charge of the stress film also increases. This is because of the longer the rubbing time, more electrons from the cotton cloth can be transferred to the stress film, thus the stress film become more negatively charged.

Experiment B: Size of the stress film with the same rubbing time

Table 2 Effect of size of stress film on the value of the charge of the stress film

Size of the stress film (cm)

3x6 4x8 5x10

Charge of the stress film (nC)

-1.4668 -3.1469 -3.3388

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

Figure 7: Graph of Effect of size of stress film on the value of the charge of the stress film

The amount of charge transfer depends on the real area of contact. Charge transfers take place in that real area of the contact. Furthermore, the fraction of area charged increases by the rubbing action which is known as triboelectric effect. For case B, the size of the stress film were increased to 4x8 cm and 5x10 cm. When the size increases, larger area of contact involved in the triboelectric effect. Thus, higher number of electrons can be transferred into the stress film which cause increases in the magnitude of the charge of the stress film.

Experiment C: Type of rubbing with the same size and rubbing time

Table 3 Effect of type of rubbing on the value of the charge of the stress film

Type of rubbing Soft Moderate Harsh

Charge of the stress film (nC)

-1.1454 -1.4326 -3.5577

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

Figure 8: Graph of Effect of type of rubbing on the value of the charge of the stress film

In this experiment, the properties of the electrostatic charges were also being studied by adjusting the type of the rubbing, which is soft, moderate and harsh. Harsh type of rubbing create greater force act on the surface of the stress film. Therefore, the electrons from the cotton cloth received more energy to jump into the stress film when both were being rubbed together. Larger amount of electrons transferred between both materials created high value of charge of the stress film. When more force is used to rub the stress film, more charges will be generated on the stress film.

Figure 9: Graph of 20 second rubbing time of the stress film

Figure 10: Graph of 40 second rubbing time of the stress film

Figure 11: Graph of 60 second rubbing time of the stress film

Figure 12: Graph of 80 second rubbing time of the stress film

Figure 13: Graph of 100 second rubbing time of the stress film

Figure 14: Graph of 120 second rubbing time of the stress film

Figure 15: Graph of the charge of the stress film with size of 3x6 cm

Figure 16: Graph of the charge of the stress film with size of 4x8 cm

Figure 17: Graph of the charge of the stress film with size of 5x10 cm

Figure 18: Graph of the charge of the stress film with soft rubbing

Figure 19: Graph of the charge of the stress film with moderate rubbing

Figure 20: Graph of the charge of the stress film with harsh rubbing

Case 2(a)

Table 4: Measurement of relative permittivity

Brand Voltage, V (mV)

Capacitance, C (nF)

Charge, Q (pC)

εr ρv , µC/m3

Empty

(Free Space)

35.1 0.45 15.795 1 0.8044

Nanogen 49.1 0.47 23.077 1.4610 1.1753

BioTHIK

66.2 0.49 32.438 2.0537 1.6520

The volume for capacitor cavity is calculated by using formula below:

V = π r2h

= π (0.025 )2(0.01)

= 0.019635 x 10−3

From this experiment, two parameters, voltage between metal plates, V and capacitance, C were measured. Then, total charges, Q, relative permittivity, εr and the volume charge density, ρv, are

calculated using corresponding equations. Based on Table 4, BioTHIK has better performance because it can held more charges than Nanogen. This shows that BioTHIK can stick more tightly and firmly without falling when applied to the real hair. Higher in relative permittivity also make BioTHIK a better dielectric However, BioTHIK has higher volume charges density which make it stores more charges than Nanogen per unit volume.

Result obtained are different from the K.Y.You, and Y.L.Then in the article Electrostatic and dielectric measurements for hair building fibers man DC to microwave frequencies. This is because different multi-meter was used in this experiment. Only Fluke 19B was provided during the experiment while the researchers used more accurate multimeter (Fluke 128). It might seems insignificant but it does contribute to inaccurate result. In addition, the surrounding environment and room temperature need to be cautious because these will affect the reading of voltage and capacitance. Inappropriate method to transfer the hair fiber from its container to the sample holder by hands is also might cause impurity of the hair fiber used which resulted in less accurate experiment result. Moreover, air gap which exist in the holder is one of the factor that cause our result different from the article.

Error can be improved by minimize the human error. Suitable method must be used to transfer the hair fiber to the sample holder. Besides that, use a better capacity cavity to complete seal the hair fiber so no air gap can exist within it. Lastly, make sure the capacity cavity is cleaned before another experiment can be conducted.

Case 2(b)

BioTHIK

N=21, L=4.4cm

Table 5: Data for BIOTHIK

Current, I (A) Magnetic Field, B (mT)

0.0 0

0.5 0.0137

1.0 0.0733

1.5 0.1358

2.0 0.1835

2.5 0.2363

3.0 0.2637

Nanogen

N=17, L=3.7cm

Table 6: Data for Nanogen

Current, I (A) Magnetic Field, B (mT)

0.0 0

0.5 0.0101

1.0 0.0766

1.5 0.1543

2.0 0.2184

2.5 0.2242

3.0 0.3960

Iron Powder

N=17, L=3.7cm

Table 7: Data for iron powder

Current, I (A) Magnetic Field, B (mT)

0.0 0

0.5 0.1102

1.0 0.1642

1.5 0.2165

2.0 0.3197

2.5 0.3251

3.0 0.3261

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

BioTHIK

Nanogen

Iron Powder

Current, I (A)

Mag

netic

Fie

ld, B

(mT)

Figure 21: Graph of B against I

From figure 21, it can be seen that for all types of solenoid cores, the value of magnetic field increases when current increases. However, iron powder core saturates at 2.0A where it gives almost a flat pattern for magnetic field exceeding this current value. The gradient of all graphs are calculated in order to obtained the relative permeability μr.

For BioTHIK,

Gradient = 0.1113 mT/A

μr=2× 4.4 ×10−2

4 π ×10−7 ×21(0.1113 ×10−3) = 0.3711

For Nanogen,

Gradient = 0.1389 mT/A

μr=2× 3.7 ×10−2

4 π ×10−7 ×17(0.1389× 10−3) = 0.4811

For Iron powder,

Saturation current, I=2.0A

Gradient = 0.1397 mT/A

μr=2× 3.7 ×10−2

4 π ×10−7 ×17(0.1397× 10−3) = 0.4839

Table 8: Relative permeability

Material Relative permeability

BioTHIK 0.3711

Nanogen 0.4811

Iron powder 0.4839

The relative permeability, μrobtained shows that these materials are not suitable to be used as cores inside solenoid due to its low degree of magnetization. However, in terms of hair fiber application, the lower value of μris desired in order to ensure that the hair fiber is attached to human hair even though there is a presence of magnetic field. Thus this experiment proves that BioTHIK gives better performance to be used as hair fiber compared to Nanogen which this data correlate with the Case 2(a).

5. ConclusionFor case 1, the experiment was conducted to determine the relationship between electrostatic charge moving towards stress film and how this electrostatic charge could affect the electronic chip. The amount of charge generated on stress film rubbed with cotton cloth under different rubbing condition was determined. Based on the result, when the rubbing time increased, the amount of charge generated on the rubbed stress film increased. Also, the larger the surface area of the stress film, the higher the amount of charge generated on the rubbed stress film. Furthermore, more charges will be generated when the stress film was rubbed harsher. Sensitive electronic devices will be damaged easily after contacted with the charged stress film. That is why for packaging and logistic, stress film like wrapping material should be handled properly to avoid vigorous and excessive friction. Similarly, precaution such as anti-static bag should be put in use in packaging of sensitive electronic devices to prevent damage of component.

In case 2 the characteristic and electromagnetic parameter of hair fiber, BIOTHIK and Nanogen is tested and analyzed. From both Case 2(a) and Case 2(b), BioTHIK is proven has better performance than Nanogen in term of total amount of charge, relative permittivity, volume charge density and relative permeability. This makes BioTHIK a better hair fiber product to be

used. This is because it can hold more charge and more resist to magnetic field which will makes it stick more tightly and firmly without falling. Therefore, material with low relative permeability and high relative permittivity will make a better hair fiber product.

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2010.Available:http://www.naturallycurlurlreading/curlproducts/curlychemist-the-cuticle-is-the-first-line-of-defense-for-ourhair

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3. K. Y. You, Y. L. Then, “Electrostatic and Dielectric Measurements for Hair Building Fibers from DC to Microwave Frequencies,” International Journal of Electrical, Computer, Electronics and Communication Engineering Vol:9, No:3, pp. 286-293, 2015.

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