RF and Microwave Engineering
Published August 26, 2025 | Version 3.0
Software Open

Nonuniform Transmission Line Analyzer 3.0

Authors/Creators

  • 1. National Institute of Technology Rourkela

Description

Transmission line Impedance Tapers are critical components in signal transmission systems, aiding in impedance matching and minimizing signal reflections. Accurate simulations are essential for analyzing the electrical performance of these tapers. This research work presents a CAD tool developed using Python that enables the simulation of different transmission line tapers using analytical and numerical methods. The CAD tool provides engineers and researchers with an intuitive graphical interface to visualize and analyze the behaviour of transmission line tapers effectively.

Technical info

Non-Uniform Transmission Line Analyser (Impedance Taper Kit)

How-To Guide
1. Start the Tool

A. Download the NUTLA.zip file from https://zenodo.org/records/16948448
B. Extract the .zip file.
C. Launch the software by opening the NUTLA.exe file.
D. The main window appears with options for Analysis Type, Approximation, Sampling, Transmission Line Type,
Z1, Z2, Electrical Length, and Design Frequency.

 

2. Choose Analysis Type

A. Analytical – Use when the taper has a known closed-form solution (e.g., Exponential, Cosine-Squared, Klopfenstein).
B. Numerical – Use for arbitrary tapers (e.g., Logis c, Error func on, User-defined).

 

3. Select Approximation (for Numerical Mode)

A. Uniform – Stepwise constant impedance segments. Simple, less accurate.
B.Linear – Impedance varies linearly within segments. Accurate for most profiles.
C.Nonlinear – Uses power-law fitting. Best for strongly nonlinear tapers.

 

4. Set Sampling


A. Uniform – Equal segment lengths. Simple, may require many segments.
B. Adaptive – Segment length changes with impedance variation. More efficient and accurate.

  • hmin: Minimum segment length (usually λ/40 at max frequency).
  • delta: Approximation tolerance (default 1e-3).

 

5. Enter Line Parameters


A. Z1, Z2 – Source and load impedances.
B. Electrical Length (θ in °) – Set taper length in degrees at design frequency.
C. Design Frequency (f0 in MHz) – Operating frequency for taper design.

 

6. Run Frequency-Domain Analysis


A. Click S-Parameters in the main window. 
B. Plots available:

  • Impedance Variation 
  • S-parameter Variation (S11, S21, etc.)
  • Group Delay Variation
  • Transmission Delay Product

7. Run Time-Domain Analysis


A. Click Time Domain in the main window.
B. Choose Input Pulse Type: Gaussian, Gaussian Monopulse, or Modulated Gaussian.
C. Set Cut-off Frequency (GHz) and Time Duration (ns).
D. First, click Calculate to get the frequency response.
E. After that, click Response for time-domain output.
F. Tabs allow viewing: Amplitude Spectrum, Phase Spectrum, Time Domain, Correlation Coefficient.



8. Generate Layout


A. Click Get Layout in the main window.
B.Choose substrate parameters (width, height, dielectric constant).
C. Generate and preview the layout by clicking Get Layout.
D. Export layout.dxf file for fabrication by clicking Save Layout.

 

 

9. Exit

Click Exit in the main window to close the software.  

 

Link: https://youtu.be/HRH_pwQmPnI

Files

Screenshot 2025-08-26 162608.png

Files (95.9 MB)

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Additional details

Funding

IEEE Foundation
The 2023 IEEE MTT-S Undergraduate/Pre-Graduate Scholarship Awards IEEEMTTS\UG\2023\2

Software

Programming language
Python
Development Status
Active

References

  • Ke Lu. An efficient method for analysis of arbitrary nonuniform transmission lines. IEEE Transactions on Microwave Theory and Techniques, 45(1):9–14, 1997.
  • M.J. Ahmed. Impedance transformation equations for exponential, cosine-sqaared, and parabolic tapered transmission lines. IEEE Transactions on Microwave Theory and Techniques, 29(1):67–68, 1981.
  • R. W. Klopfenstein. A transmission line taper of improved design. Proceedings of the IRE, 44(1):31–35, 1956.
  • Wikipedia contributors. Sigmoid function — Wikipedia, the free encyclopedia, 2023. [Online; accessed 8-November-2023].
  • Rakesh Sinha, Ranadhir Chatterjee, and Hungsun Son. Comments on "microstrip tjunction power divider with exponentially tapered transmission lines". IEEE Microwave and Wireless Components Letters, 27(11):1037–1038, 2017.
  • Ranadhir Chatterjee and Arijit De. Theory of optimum taper for distortionless pulse transmission. IEEE Transactions on Microwave Theory and Techniques, 70(4):2124–2134, 2022.
  • https://eng.libretexts.org/Bookshelves/Electrical_Engineering/Electronics/Microwave_and_RF_Design_III_-_Networks_(Steer)/07%3A_Chapter_7/7.5%3A_Tapered_Matching_Transformers
  • R. Sinha and S. Das, "Comments on "Theory of Optimum Taper for Distortionless Pulse Transmission"," in IEEE Transactions on Microwave Theory and Techniques, vol. 73, no. 8, pp. 5607-5610, Aug. 2025, doi: 10.1109/TMTT.2025.3537320.
  • S. Das and R. Sinha, "Design and Analysis of Logistic Impedance Taper for Distortion less Pulse Transmission," 2024 IEEE Microwaves, Antennas, and Propagation Conference (MAPCON), Hyderabad, India, 2024, pp. 1-4, doi: 10.1109/MAPCON61407.2024.10923547.