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Simple Lossless Tuner with Bias Tee (Closed Form): LTUNER2



The LTUNER2 element is a frequency-independent, lossless network which transforms the impedance Z0 seen at port 2 to a user-defined impedance seen at port 1. Specifying the magnitude and angle of the reflection coefficient as well as the system reference impedance sets the user-defined impedance. It is assumed that port 2 of this element is loaded in the same Z0 as specified for the element. A bias voltage can be applied to port 3 to bias a device connected to port 1, eliminating the need for a BIASTEE element.


Name Description Unit Type Default
ID Element ID Text TU1
Mag Magnitude of gamma looking into port 1   0.5
Ang Angle of gamma looking into port 1 Angle 0 Deg
Zo System impedance Resistance 50 ohms

Parameter Details

The input impedance, Z, at port 1 is calculated as:

for f>1Hz else Bias

Parameter Restrictions and Recommendations

  1. -1 < Mag < 1. If Mag is less than or equal to -1, it will be set to -0.99999. If Mag is greater or equal to 1, it will be set to 0.99999.

  2. Zo must be greater than or equal to 0.1 ohm.


This element does not have an assigned layout cell. You can assign artwork cells to any element. See “Assigning Artwork Cells to Layout of Schematic Elements” for details.

Recommendations for Use

NOTES: The impedance seen at port 1 of the element is a lossless transformation of an impedance Zo seen at port 2, to the specified reflection coefficient. If port 2 is not loaded with an impedance equal to Zo, the reflection seen at port 1 will not be as specified.

This element can be used to replace a lossless matching network. However, when comparing S-parameters to an actual realization of this matching network, the phase of S12,S21and S22 may not agree, due to the incomplete specification of the network by only defining only the reflection at port 1. A finite length of ideal transmission line (impedance = Zo) placed at port 2 of the tuner may be required to make the make S-parameters agree.

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