RF, Digital Radio and
Work in assigned project groups.
The objective of this project is to simulate and measure s-parameters.
NOTE: Use the Project Report Template and keep answers to questions on consecutive sheets
of paper with all plots at the end.
IN NO CASE may code or files be exchanged between students, and
each student must answer the questions themselves and do their own
plots, NO COPYING of any sort! Nevertheless, students are
encouraged to collaborate in the lab session.
Part 1: Measurements
- We will measure s-parameters of a 6-foot length of 50-ohm transmission line terminated by a 25 ohm load
- The 25 ohm load will be comprised of the 50-ohms port 2 of the
instrument in parallel with a 50-ohm termination through a BNC-tee
- Set up the S-parameter measurement as illustrated below,
with a BNC tee and 50-ohm term at port 2 to create the 25 ohm
- Have the instructor adjust the display to the following
- Check that the start/stop are 1 MHz and 50 MHz (bottom left
above), and that the two Smith charts are S11 and S22 (blue
- Adjust marker1 to 1 MHz, and adjust marker2 to where the
plot crosses the Smith chart on the right (as shown in the
- See the arrows in the previous
photograph for the location of the marker controls.
- Save a cellphone picture (for this instrument a USB port is not available) of the network analyzer display as
above (but with markers correctly positioned) and paste it
into your report. SEE BELOW FOR THE REPORT TEMPLATE
- What are the two un-normalized impedances (assume closest
pure resistance) at the two markers, and what is the
transformer ratio (ratio of the 2 resistances)?
- Compute reflection coefficient Gamma, and return loss seen from port1 at 1MHz
(assume the transmission line is a wire).
- From the upper right plot of S11 in dB, what is the measured
S11 in dB at 1 MHz?
- Why do you "see a circle" on the Smith chart of S11, but not
on the Smith Chart of S22?
Part 2: Simulation
- S-parameter simulations
- Download the 7zap
archive as follows:
- Download the 7zap archive RFcourse2015_proj2_wrk.7zap
to your ads directory
- Use MenuBar::File::Unarchive to extract the project into
your ADS directory as follows
- You should find a new directory RFcourse2015_proj2_wrk
created in apps/ads
- Run ADS and open the new RFcourse2015_proj2_wrk workbook
by double-clicking it
- We will be making S-parameter measurements that correspond to a situation similar to our project 2 simulation.
- Open the p2sparamLine schematic in the workbook by clicking
that schematic design file.
- Run the simulation, and you should S-parameters and Smith
chart somewhat different from that illustrated below:
- Right-click and select "copy cell" to make a copy of this design
- Edit the new copy so that it reflects the scenario in the
- Change the transmission line to a TLIN component as shown above, but with
50 ohms impedance and with
E=90 at whatever frequency in MHz best corresponds to your lab
measurements, set source Term1 to 50 ohms, and load Term2 to 50 ohms,
and add a 50-ohm resistor in parallel to term2 to ground. Change
the S-parameter sweep to go from 1 to 50 MHz in 1 MHz steps.
Adjust to an appropriate-length the TLIND line such that it
reflects your measurements using the the approximately 6-foot
long line in the lab (if you want to estimate it before going
into the lab, assume a velocity of 0.7 c, and length of 6
- Save a snapshot of your new schematic and paste it into your
- Run the simulation, and plot the Smith chart (somewhat
different from that illustrated below):
- Set two markers as above (one at 1 MHz and the other at
where it crosses the axis on the right side
- What are the two un-normalized impedances (assume closest
pure resistance) at the markers, and what is the transformer
ratio (ratio of the 2 impedances)?
WARNING !! ====================================
- **** WARNING **** YOU MUST USE
THE PROJECT REPORT TEMPLATE Below:
- See the Project
Report Template at bottom of this page
- A well-written report/paper is
- STRONGLY RECOMMEND that you read IEEE
authorship series: How to Write for Technical Periodicals
- Clearly describe everything, including:
- variables in block diagrams
- variables in formulas
- units of variables kHz, pF, nH, m, s,
- all traces on plots
- all curves on plots
- all results in any tables
- Minimum required data content for
your report and demos
- Required theory/formulas numbered as below:
- (1) Reflection coefficient formula at port 1 at 1 MHz for 50-ohm source, 50-ohm line, and 25 ohm load
- (2) S11 formula at 1 MHz for 50-ohm source, 50-ohm line, and 25 ohm load
- (3) Theoretical S21 at 1 MHz for 50-ohm source, 50-ohm line, and
25 ohm load. Hint: you must compute the power delivered to term2
delivered from the source.
- Required figures:
- Any illegible plots receive zero credit (must be able to read all numbers, axes, labels, curves, grids, titles, legends)
- All plots must of professional quality as in IEEE papers
Required tabular data content:
- LEGIBLE ADS schematic of the system, with appropriate caption.
- LEGIBLE smith-chart plot of simulated S11
- LEGIBLE dB plot of simulated S21 and S11 on a dB scale from 0 to -10 dB
- LEGIBLE cellphone picture of measured s-parameters like Figure 001 of this webpage
- Table of s-parameters at 1 MHz (assume approximately dc) with 3 columns: parameter, theoretical value, simulated value
- Row 1: theoretical and simulated S11
- Row 2: theoretical and simulated S21
- Row 3: theoretical and simulated S12
- Row 4: theoretical and simulated S22
- See report template below
NOTE ReportTemplate: Use the Project Report Template
YOU MUST ADD CAPTIONS AND FIGURE
NUMBERS TO ALL FIGURES!!
Copyright © 2010-2018 T. Weldon
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