## 018/100 Short-circuited Transmission Line

100 ADS Design Examples Based on the Textbook: RF and Microwave Circuit Design

November 2019

Michael Benker

**Example 2.11-2A: Calculate the input impedance of a short-circuited microstrip transmission line for a given electrical length of the line.**

This circuit was built with a quarter-wave microstrip synthesized for 10 GHz with given substrate (conductivity of gold) using the LineCalc tool.

The following results conclude that a short-circuited quarter-wave transmission line has high impedance, similar to an open circuit. A short circuited transmission line that is not a quarter-wave transmission line will not have high impedance as demonstrated by frequencies far outside of the range of optimization (10 GHz). This phenomena is is consistent with electromagnetic theory on transmission lines.

Theoretical relationship between transmission line length (short-circuited) and it’s imaginary impedance component:

## 019/100 Open-Circuit Transmission Line | RF/Photonics Lab 2:46 pm

onNovember 17, 2019 Permalink |[…] To construct this circuit, a termination of 1 MOhms is used to simulate an open circuit. As the electrical length in degrees varies with frequency (the wavelength), a static electrical length of a transmission line varied over many frequencies will suffice to demonstrate the reactance of a varying electrical length transmission line. The following circuit was created with a transmission line optimized for 10 GHz, similar to the Short-circuited Transmission Line: […]

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