The City College of New York English 21007: Writing for Engineers Semester: Spring 2018

Lab Report 1:
What Materials Can Block a Wi-Fi Signal?

Instructor: Maryam Alikhani

Students: Handell Vigniero Hasibul Hasan

Cristian Lema Rhona Kosumi

Abstract

The objective of this project is to measure the effect of different materials on the signal strength of a wireless router. The method used to determine the effect of these materials involved several trials of blocking a router from a Wi-Fi connected device with a material and recording the signal strength compared to the signal strength prior to being blocked. The results showed that a steel pan and the human body caused the most attenuation or weakening of the signal. The study’s conclusion indicated that materials with higher conductivity and frequency caused the greatest drop in Wi-Fi signal.

Introduction

Wi-Fi is a technology that allows computers and mobile devices to connect to the internet or connect with one another wirelessly within a particular area. This technological feat is accomplished with the use of radio waves, a type of electromagnetic radiation.
Here’s how;

• ●  “A computer’s wireless adapter translates data into a radio signal and transmits it using an antenna.”
• ●  “A wireless router receives the signal and decodes it. The router sends the information to the Internet using a physical, wired Ethernet connection.”( Brain, M., Wilson, T. V., & Johnson, B, 2016)The different types of electromagnetic radiation are part of the electromagnetic spectrum, which are differentiated by their frequency, or number of waves per second. Electromagnetic radiation can be weakened, or attenuated when it passes through different materials. This works in the same way as visible light, another electromagnetic radiation. Visible light can be blocked completely by materials such as wood and metal, while other materials, such as water, will only slightly weaken the amount of visible light that passes through it. Likewise, different materials can weaken the radio waves used by Wi-Fi. Materials with high conductivity effectively absorbs radio waves, thus affecting the strength of a Wi-Fi signal that passes through it. The signal strength is measured in units called Decibel-milliwatts. A value closer to 0 has a stronger signal than dBm values farther away from 0. Thus, -35 dBm is much stronger than -110 dBm. This study explored how signal strength, in dBm, is affected when the device using Wi-Fi is covered by several different types of material. Our experiment will utilize an iPhone and several materials to test out the effect of each on the signal strength of the device. Our hypothesis is that the steel pan would be the one to weaken the Wi-Fi signal the most, because of the fact that metals are great conductors. Thus, the steel pan will affect the Wi-Fi signal the most.

Methods and Materials

• ●  A wireless router
• ●  A wi-fi enabled device (smartphone, tablet, laptop, desktop)
• ●  A program to determine the strength of the current wi-fi signal (in dBm, ordecibel-milliwatts)
  1. Windows device: WiFiInfoViwer or WirelessNetView
  2. Android device: Wifi Analyzer
  3. Mac device: Wifi Strength Indicator
• ●  1 Steel pan
• ●  1 Sheet of aluminum foil (enough to cover device)
• ●  1 Piece of cardboard
• ●  1 Glass pan
• ●  1 Water-filled glass
• ●  1 Human body
• ●  1 Notebook to record data

Procedure

1. Download and install a program on your wireless device that can be used for experiment to measure the signal strength of a wifi connection (in dBm).
2. Make sure the program works and test it out by walking around with the program open while observing the changes in signal strength.
3. Pick a location to perform tests. It is important to keep the location consistent as well as the position of the wireless device. Ideal location:
   • ●  Same room as wireless router
   • ●  Do not have any obstacles between wireless device and the router (includingyourself)
4. Start the experiment by measuring the signal strength with no blocking material. It isimperative not to move the router or wireless device nor the blocking material because it will alter the results of the measurement. Measure the signal strength in dBm using the program and record the value in your notebook. Perform this test 8 times. This will be the control group
5. Now set up your first blocking material by placing it in front of the router so that it completely blocks the router from the wireless device. Record the resulting signal strength. Perform a total of 8 trials.
6. Repeat step 5 for each of the remaining blocking materials.
7. Once all the data is collected, take the average signal strength in dBm for each materialused, including the control group.

8. Calculate how much the signal strength has weakened by subtracting the average signal strength of each blocking material to the average signal strength without a blocking material. Record this data into your notebook.

9. All the data that has been recorded should be entered into a data table listing the signal strength measured after each trial as well as the average signal strength of each material.

10. Create a bar graph with the material type on the x-axis vs the amount of attenuation (how much the signal was weakened) acquired from step 8 on the y-axis.

Results

The results revealed the signal strength in dBm of the iPhone at the time of each trial. The strongest signals are the ones closer to 0. There were 8 trials for each material, as well as 8 trials without the use of a material as the control. The control group was labeled regular. The data table lists the measurements acquired after each trial. The bar graph shows the amount of attenuation that each material caused. In other words, the average signal strength of each material was compared to the average signal strength control group (regular). The materials with greater conductivity affected the signal strength the most. The human body showed the most disruption of the Wi-Fi signal.

Discussion

The WiFi signal strength experiment was very easy to conduct and was completed without any significant complications. After placing the WiFi router and the Android wireless device (six feet apart) on an even surface, the signal strength was recorded. Since there was no material in between the two objects in this initial experiment, this is where the WiFi signal strength was the highest.

For each material we tested the signal strength on, we recorded eight trials. Table A shows the recorded signal strengths (in dBm) paired with the material used. Table B shows the amount of attenuation (how much the signal strength weakened) compared to the base experiment where no material was placed between the router and the smart phone device. (NOTE: The further the signal strength is from 0, the weaker the signal strength.)

According to the data results, the material that had the highest attenuation was the human body. When a human body was placed between the router and the smartphone, the average signal strength was -47.825 dBm. This high value suggests that the electromagnetic radiation weakened most while passing through the human body. This is due to the fact that our bodies are composed of 70% water, and water is an obstacle for electromagnetic radiation causing the signal strength to become attenuated. Also, human body is electrically conductive meaning that it absorbs a fair amount of RF (radio frequency) or a signal. When the water filled glass was placed between the route and smartphone, the attenuation was the third highest. This shows that water negatively contributes to the weakening of the signal strength.

What Materials Can Block a Wi-Fi Signal? 11 Steel pan is another material with the second highest signal strength. WiFi devices

communicate using radio waves. Much like radio waves, visible light also cannot pass through steel pan. For example, when you shine a flashlight through a steel pan, you cannot see it from the other side. As a result, the visible light was attenuated. Similarly, radio waves (electromagnetic radiation that wireless devices use to communicate) also have a hard time passing through the steel pan which is a conductor of electricity. Due to this, we can say that steel pan is another material that can significantly damper WiFi performance.

Based on observations, cardboard resulted in the least amount of attenuation. The average WiFi signal strength of cardboard was -33.125dBm. The material that caused the second least attenuation was glass pan and third least attenuation was aluminum foil. These materials had the smallest impact on the signal strength as well as the weakest conductivity. Therefore; radio waves did not become as weak when they passed through these materials.

Conclusion

After collecting the data and discussing the results, we have come to the conclusion that human body was the most successful at blocking Wi-Fi signals from the router to the IPhone. This differs from our initial hypothesis where we stated that the steel pan would affect the WiFi signal the most because of the fact that metal is a great conductor and that it absorbs electricity. Since radio waves are electromagnetic, it also absorbs those. “Wireless signals affect radio waves. Radio waves are formed by a variable electromagnetic field. Unfortunately, metal is a conductor of electricity and magnetism, and so it absorbs radio waves. The more metal a building has in its structure, the worse the radio reception is for the people inside” (Cooper, S. B, 2016).

Steel was proved to be the second strongest Wi-Fi signal blocker compared to the rest of materials, therefore we very pretty close to our initial hypothesis. We have also concluded that materials with the higher conductivity tend to be more successful in blocking Wi-Fi signals, in our case; Human Body.” A person’s body contains a large amount of water which is an excellent absorber and conductor of an RF signal” (Co., C. 2014).The opposite can then be said for materials with lower conductivity, since they are the least successful in blocking Wi-Fi signals between two objects.

References

Brain, M., Wilson, T. V., & Johnson, B. (2016). How WiFi Works. Retrieved March 10, 2018, from https://computer.howstuffworks.com/wireless-network1.htm

Pvt. Ltd, M. (Ed.). (2014). Dos and Don’ts of Wi-Fi connectivity: Maximizing Range and Reception. Retrieved March 10, 2018, from https://www.mistralsolutions.com/dos-donts-wi-fi-connectivity-maximizing-range-reception/

Co., C. (2014). Understanding the Effect of the Human Body on RF Signal Propagation. Retrieved March 10, 2018, from http://www.connect802.com/human_body_rf.htm

Cooper, S. B. (2016). How Does Metal Affect a Wireless Signal? Retrieved March 10, 2018, from https://www.techwalla.com/articles/how-does-metal-affect-a-wireless-signal

Handell Vigniero:

From the course goals:

Reflections

I have enhanced my writing with strategies such as drafting, revising, and editing. I negotiate my writing goals and audience expectation by providing clarity throughout my work getting my point across to the specific audience. Through this lab report, I have been able to work in a group and engage in collaborative aspects of writing processes. Formulating a hypothesis and experimenting has allowed me to formulate and articulate a stance throughout my writing. The internet also played a very important part in the making of this lab report as a source of information and sources. Using the sources and information allowed me to practice evaluating, integrating, quoting, paraphrasing, summarizing, analyzing, and citing.

Reflection:

The process of writing this report was very collaborative. As a group, we had to first find a subject of interest and assign roles to get the project done. These were also challenges because we wanted to select an interesting experiment that was not too difficult. That took some searching. Another challenge was making sure that everything was done on time and that the group members could communicate consistently. I learned that I enjoy writing more when it is about an interesting subject. Through collaborative writing, I learned that the different aspects and writing styles between group members can make a project a lot more interesting. My part in the group consisted of making sure everything got done on time. I also wrote the basic outline of the project, as well as the abstract, intro,materials, procedures, and results sections.

Hasibul Hasan: From the Course Goals:
In the process of producing this lab report, I have applied various course writing goals.

One goal I have applied was the use of “multimodal composing” to create an effective writing piece to enhance the lab report. After recording the results of the experiment, we created graphs to help show a clear distinction between the signal strengths when the electromagnetic radiation

What Materials Can Block a Wi-Fi Signal? 15 goes through each material. The bar graph we added enhances our data collected in the table. Another way we applied multimodal composition was adding images taken during the experiment. This addition brings the experiment to life on paper. The integration of multimodal composition in the writing helps us present our lab report better and helps the reader understand our experiment better. I have also applied the course goal of enhance strategies for reading, drafting, revising, editing, and self-assessment. This was crucial to the production of this lab report. Technical writing is difficult to compose because I had to be very consistent and use relevant vocabulary words. In the process of doing so, I made many errors. As a result, I had to constantly reread everything, revise my work and edit any mistakes I made along the way. This goal was relevant because I had to revisit my work many times and add technical vocabulary words to make the lab report very informative and formal. Lastly, we definitely engaged in the collaborative and social aspects of writing. Everyone was assigned different aspects of the lab report. However, we came together at the end to tie all our works together.

Reflection:
This technical lab report was not very different from any project I have completely.

Group collaboration was the most essential part of completing this task. Everyone had to stay on top of their assigned work or the lab report could not have been completed. I think it was a very successful lab report with some minor challenges. I had the task of conducting the actual experiment. Everyone had a different schedule so it was nearly impossible to do the experiment together. I found it somewhat challenging to use the mobile app to obtain the signal strength and record it at the same time because the numbers are constantly changing. As a result, I asked my little sister for assistance. Besides this minor challenge, the lab report was not very difficult. Next, I also assess the data in the discussions section. Although some member had minor disagreements, we came to a consensus at the end. As a result, I have learned to communicate better and pick and choose which information is more relevant to include and which information is not.

Cristian Lema:

From the course goals:
From this assignment I was able to enhance how I utilize resources and materials. Engage in collaborative and social aspects of writing processes throughout the assignment. Establish a solid stance and provide strong supporting information to solidify my claims.
Also being able to enhance the way I go about reviewing and editing my peers work.
Reflection:

This was overall a fun assignment. I learned how to engage in conversation with my group members in which we collaborated on how to make our writing better and discuss the experiment. As I took big part in the conclusion and discussion of this assignment, we all interpreted the data differently. I learned that everyone has many different views and opinions, therefore establishing agreements and compromises was very important so that everyone could feel heard and respected. We learned a lot from each other, in which how we all went about doing our work and how we interpreted the results of the project.
Rhona Kosumi:
From the course goals:

While doing this report, I enhanced strategies for reading, drafting, revising and self-assessment. Negotiated my own writing goals with my group. It also helped me strengthen my source use practices (including evaluating, quoting, paraphrasing, summarizing, analyzing and citing sources) which I found with the help of the internet and a handful of online databases. Reflection:

This is not my first lab repot I am writing. The group was very collaborative and helpful. One of my challenges was the fact that I had a few midterms and not enough time to catch up with the rest of the group. They did a lot of writing for this lab report. My role was to edit the whole lab report and use quoting, paraphrasing, references and the APA style . The experiment we chose was very informative as well. Overall, it was a great experience and a pleasure to work with my teammates.