EEE161 Applied Electromagnetics Laboratory 1athena.ecs.csus.edu/~milica/EEE161/EEE161/NewLabs/Spring2018/Lab1S18.pdf · If it did not work properly, explain the problem and how you

Dr. Milica Markovic Applied Electromagnetics Laboratory page 1

EEE161 Applied Electromagnetics Laboratory 1

Instructor: Dr. Milica MarkovicOffice: Riverside Hall 5026

Email: [email protected]:http://gaia.ecs.csus.edu/˜milica

1 Learning Objectives

In this lab you will

1. Analyze the effects of coaxial cable to step and sinusoidal voltage at the input and the outputof the cable.

2. Interpret phase and time delay as they relate to voltages and currents on transmission lines.

3. In ADS create a workspace, schematic diagram

4. perform Transient simulation with a coaxial cable

5. Label nodes, then use an equation in data window to display results

6. display simulation data, tune the circuit parameters and save files.

2 Report

Consult with your lab instructor what kind of report they want to see for each lab!.You may snip the text of the problem assigned, then just cut and paste in a word file the circuit

and the simulation you performed. All figures should have figure numbers and captions. Explain thesteps you are taking, and thoroughly explain each simulation results. Have you expected these resultsor not? Do you think the simulation is correct? How does the simulation relate to other simulationsperformed? What does the result mean? Is it reasonable? Submit ONE report per group in SacCTfor Labs 1-7. Final Antenna Project report will be done by individual students. Rubric is availableon the Laboratory assignment web site. The general outline of the report is given below.

1. Title: THE Ws. Who (produced the report), what (circuit, equipment, components -¿ BOM-bill-of-material: device/element type, manufacturer, model number, type number, value, mea-surement unit, how many), when, where.

2. Objectives. Briefly describe the objectives of the project: the circuit to be designed, imple-mented, and tested, and its intended use (Do some research on what can this circuit be usedfor).

California State University Sacramento EEE161 revised: January 22, 2018


3. Specifications. Describe the technical and performance specifications that must be met by thecircuit or system that you are to design. If you don’t have specs to start with, make some up.What are the specs that your circuit could have? Specify target value, min and max.

4. Design methodology. Describe the procedures you followed in designing your circuit. Explainyour design decisions and write down all equations used and calculations made. Discuss de-sign factors. Sketch rough schematics of your circuits. Include your ADS/Momentum circuitand graphical outputs. Remember that hand calculations and ADS/Momentum simulationsare done ahead of the measurements to understand the circuit and results that are to beexpected during measurements. Even though your laboratory doesn’t ask you to do somehand-calculations and or simulations doesn’t mean you don’t have to do them. All measureddata need to be tested as reasonable by either hand-calculations or simulations, but preferablyboth.

5. Implementation. Draw detailed schematics of all circuits you designed and built. These shouldbe very complete, using functional schematics. Label each terminal with its function whereappropriate and give the pin number to help with troubleshooting. Measure the values ofresistors and capacitors when they are critical to performance. Show the circuit implementationon a breadboard (if available).

6. Troubleshooting. Describe the procedures followed in troubleshooting your circuits. Don’tsimply write “I tried it and it worked,” but instead describe the test configuration, test signalsapplied, and measurements taken. Discuss how you concluded that it was working correctly.If it did not work properly, explain the problem and how you solved it. Discuss any redesign(or re-wiring) that was required. Keep a list of the equipment used. Since this list will notchange often, list your equipment in the front of your notebook, and then list any changes asthey occur. Give the manufacturer, model number, and serial number.

7. Test and evaluation. Explain in detail the test set-ups and the measurements taken. Provideclear, organized graphs, performance tables and observations. Provide the information fromseveral repeated measurements, if available. Graphs should be drawn when the measurementsare taken. In this way, you can visually detect anomalous values and quickly check thesemeasurements to verify their accuracy. Explain what the data means by describing how itagrees with the corresponding mathematical model. Your final report should be more thanjust a collection of tables, graphs, and equations. Your interpretations and explanations ofthis material is the most important part of the report. If you realize that your data is not inagreement with theory, then explain why you think it is in error and what data you expectedto record.

8. Results Provide clear summary of results. Discuss any critical design factors. Compare the ac-tual measured performance with the theoretical and simulated performance and errors. Discussrepeatability. Discuss alternative approaches.

9. Conclusion. Summarize the work accomplished in such way to clearly relate results and objec-tives (or other parts of the report) to conclusions.



10. Lessons Learned and Future Work. Desicribe your learning experience in this lab:

(a) What new information have you learned?

(b) What did you do during the lab, or elsewhere, that caused you to learn it?

(c) You want to learn the material in depth. What more do you want to learn? item Whatwould be the next set of steps to understand this material better or improve the design?Propose a set of experiments to probe further.

11. Appendix Attach all data sheets, scans of the original data from the laboratory notebook, (andtest if applicable), and any other information that is used for the report. For your graphs, tablesetc, ADS, Matlab, Excel. If you have to do a hand plot, use straight edge. Students shouldtake advantage of the spell checkers and grammar checkers built into most word processors.

3 ECS Login

You need to have ECS login and password. This login is different from CSUS login (akaSaclink login) that you use to check your email. If you don’t have the login, go to theRiverside Hall second floor computer lab and request a login from IT. You will not beable to login to ECS computers unless you have ECS login.



4 Coaxial Cables - Background

Coaxial cables are used extensively in electrical engineering. Some examples are: Distribution ofCable TV, Connection between antennas and power amplifiers in base stations for cell phones, someinternet cables are coaxial (what is usually called an Ethernet cable is a twisted-pair cable, not coax).Figure ?? shows an RG-59 coaxial cable.

Figure 1: RG-59 Coaxial Cable. A-Plastic Cover, B-Woven Copper Shield, C-Dielectric Insulator,D-Solid Copper-Clad Steel Wire. https://en.wikipedia.org/wiki/Coaxial cable

Google −→ Search for and download Data Sheet for Pasternack RG-59 coaxial cable. An excerptfrom RG-59 data sheet is shown in Figure 1.

5 Speed of electromagnetic waves

Electromagnetic waves propagate in air (εr = 1) with the speed of light c=3 108ms

. However, indielectrics where εr > 1, the speed is:

v =c√εr

(1)

Q−→ Which dielectric is used in RG-59? Calculate the speed of waves in RG-59,then compare it with the data sheet. How is data sheet expressing the speed? Can youexplain what is this the percentage of?

Now you know how to calculate the speed of electromagnetic wave. How much time will anelectromagnetic wave need to travel over an 11.5 inch line if the dielectric in the line is PE (Polyethy-lene)? This time is called ”time-delay” τ . Remember that the waves travel with constant speed,Equation 2. If the distance traveled is d, and the speed is v, what it the time τ , Equation 3, thatthe signal needs to travel distance d? Be careful with units. The speed of em waves, c, is given in m

s

and the distance is given in inches. You need to convert units first.


https://en.wikipedia.org/wiki/Coaxial_cable


Figure 2: Excerpt from RG-59 Data Sheet

v =d

t(2)

τ =d

v(3)

Next, we want to know if a sinusoidal signal at frequency f = 0.5GHz is delayed for about thetime τ , what will the phase shift be? The sinusoidal signals are written as v(t) = sinωt. If the signalis delayed for the time τ , then the delayed signal v(t − τ) is given in Equation 4. If we multiplythrough ω with t and τ to get Equation 5

v(t− τ) = sin (ω(t− τ)) (4)

v(t− τ) = sin (ωt− ωτ) (5)

From here, by inspection, we see that the ”phase” is given by Equations 6-7.

θrad = ωτ (6)

θrad = 2πfτ (7)

In degrees, using unit conversion, the phase shift is

θdeg = 360 f τ (8)



6 How to login to Hydra to access ADS

We will use Keysight’s (former Agilent, even former-er HP) ADS. You can simulate circuits usingvarious simulation techniques in ADS: AC simulation, Transient simulation, Small-Signal simulation,Harmonic Balance simulation, Envelope simulation etc. Each of these is targeted to a specific typeof circuit and application. In this class we will first use Transient simulation. This is a simpletime-domain simulation, which means that the circuit is solved by solving differential equations forvoltages, just like what you did in ENGR17. Transient simulation results will display ”transients”as well as ”steady-state” solution for voltages and currents. Transients are voltages and currentsthat occur in the circuit when we turn on the generator, and before they settle to their permanent,steady-state values.

First login to the computer that your lab is held in with ECS login and password.

1. If you are accessing Hydra from computers running Linux (for example from RVR3009), followdirections provided by the instructors.

2. If you are accessing Hydra from computers running Windows, search for ”Remote DesktopConnection”. To Login use

ECS\USERNAME

and your password.

3. It is very important NOT to close any black windows that will start poping up when you loginto Hydra. If you do close one by accident, just log out, and log back in again.

4. Find ADS on the list of programs. It is usually called ”Advanced Design System (year)”.

5. Open a new workspace, by following step-by-step instructions given in Figure 3.

6. You have to save this new workspace on T: drive. ADS will not allow you to save it to C: drive!If you don’t have the T: drive, check step c) above!

7. Click on the Schematic icon on the top bar of the “Advanced Design System (year) (Main)”window.

8. Do not select any templates, and cancell ”Schemtic Wizard” window

9. The Schematic Window should open.



(a) Go toStart, AllPrograms,AdvancedDesign System

(b) Close this window (c) This is the main ADS window.

(d) Create new workspace. (e) Name your new workspace as HW1 wrk,then click next, next,...,finish

Figure 3: Create a new workspace.



7 Setup a transient simulation of a coaxial cable with step

voltage in ADS

Sometimes it is not quite clear why do we need to study coaxial cables. After all, in EEE117 lab weuse coaxial cables to connect the generator to the breadboard, but we don’t make any assumptionsor considerations about it. This is because the frequency of the signals we’re using in EEE117 isvery low. When the frequency increases, transmission line effects become significant. In this sectionwe’ll start studying how and why transmission lines effects occur in circuits.

We will use ADS to setup the simulation shown in Figure 7(a) on a schematic diagram. Firstadd the model of a coaxial cable by following steps below.

1. Open a schematic diagram in ADS and under TLines ideal, select COAX GND, and place iton the schematics, as shown in Figure 4(a).

2. Now, using data sheet from Figure 2 enter the correct parameters A, Ri, Ro. For Ro use theoutside radius of the coax. Set T=0, Er=2.25 (Coaxial cable’s dielectric is PE - Polyethilene),lenght L=11.5 in, leave Cond1 and Cond2, Mur, TanD as they are.

Now we are ready to add sources. As shown in Figure 5, from “Sources time-domain” pull-downmenu, select Step, and from Lumped Components pull-down menu select a resistor. Set the resistance

of the resistor to 75Ω. From Simulation-Transient pull-down menu select TRANS . To setup thetransient simulator, double click on the Transient Simulation on your schematic diagram. Then:

1. Set Start time to 0 ns (it is likely already set to 0ns)

2. Set Stop time to 10 ns

3. Set MaxTimeStep to 0.1 ns (this is the sampling rate - you will learn more about that inEEE180)

4. Click on the Integration tab and set the ”Time step control method” to Fixed. This meansthat the simulator will use only the time step specified.

5. Connect the circuit with wire (red arrow) and add ground (green arrow)

6. Label the input and output voltage nodes with Vin and Vout by using ”NAME” icon in Figureabove.

7. To simulate the circuit, click on the Simulate pull-down menu from the top of the schematicdiagram, then click on Simulate (or click on the gear icon on top of the schematic diagram, orpress F7 on the keyboard).



(a) Placing a model of a coaxial cable in ADS (b) Schematic representation of a coaxialcable model parameters in ADS

(c) Description of coaxial cable model parameters in ADS.

Figure 4: Simulation of coaxial cable in ADS.

New ”Data Display” window will open. Follow directions as shown in Figure 6 to display inputand output voltage. You should end-up with the Data Display as shown in Figure 7.

Q−→Why is the otput signal delayed for about 1.43 ns? In your answer, use at leastthe following vocabulary words: speed of electromagnetic waves, dielectric, dielectricconstant, coaxial line length, time delay.



(a) Resistor under theLumped-Element pallete.

(b) Time-domain step voltageunder Time-Domain voltages.

(c) Transient simulation under theAimulation-Transient pallete

Figure 5: Location of various circuit elements under Palette.

8 Setup a transient simulation of a coaxial cable with sinu-

soidal voltage in ADS

In this section, you will repeat the previous simulation, but this time we will use a sinusoidal gener-ator. Save the schematic diagram you made with a different name. For example, ”sinusoidalsignal”.Then remove the step voltage and from the same pallete (time-domain signals) replace it with

V_1 Tone

. Label the input node with Vin and output node with Vout. Simulate the circuit and display the



(a) Click on rectangular plots and place it in Data Window. (b) Select the variable that you want to display,click add.

Figure 6: Presenting simulation results in ADS.

input and output voltages as a function of time (this is the default for transient simulation). Observethe time delay, as shown in Figure 9.

Q−→ How does this time delay compare with the step simulation? Explain why isthis so.

Now, follow instructions on how to add an equation to the ”Data Display” as shown in Figure 10.Display the rest of the plots as shown in Figure 9. When you are ploting input and output voltage,you have to select ”Add Vs” then select equations, and new variable you just defined. See Figure 10.



(a) Transient simulation of voltages at the input and outputof a coaxial cable.

(b) Simulation results.

Figure 7: Simulation of coaxial cable in ADS.



Figure 8: Schematic diagram of a setup for transient simulation of a sinusodial signal on a coaxialcable.



(a) Transient simulation of sinusoidal voltages at the input and output of a coaxial cable.

(b) Simulation results.

(c) Simulation results.

Figure 9: Simulation results of the sinusoidal voltages at the input and output of a coaxial cable inADS from Figure 8.



(a) Select Eqn (b) Type your equation.

(c) Your equation is displayed. (d) Click on rectangular plots in Data Win-dow(not shown above), then select Equationsas shown, and pick gain from the list.

Figure 10: Plotting equations example.


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EEE161 Applied Electromagnetics Laboratory 1athena.ecs.csus.edu/~milica/EEE161/EEE161/NewLabs/Spring2018/Lab1S18.pdf · If it did not work properly, explain the problem and how you