rodv92
Newbie level 4
I am struggling to understand the behavior of this Marchand balun.
Since I am still learning to use HFSS 13 and still learning microwave design, I may have done something not right...
This is a simple microstrip Marchand balun that I am trying to adapt to 1.8 GHz f0.
I connected a loop to the Balun balanced terminals to act as an antenna.
I know that a one wavelength loop in free space should have an impedance of around 100 ohms, and the balun is a 1:1 50 ohm design (based on "a new planar Marchand balun design"), so it is not matched. it's basically just a test.
And also, it is not a perfect loop since the balun terminals are somewhat spaced.
The problem I have is a really low real impedance (0.04 ohm), while the imaginary part is 14 ohms.
I designed the balun using DesignSpark and converted from Gerber to DXF using Diptrace.
The excitation comes from a lumped port with a dummy box at the side of the PCB. HFSS says that it is connected to only one conductor. I wonder if it is because of bad geometry or because the ground plane and the balun arms are shorted to ground by pins (by design, altough the unbalanced center conductor is not shorted to ground)
the port box seems to touch both ground plane and microstrip center conductor.
I'd appreciate any help.
HFSS 13 file attached
Since I am still learning to use HFSS 13 and still learning microwave design, I may have done something not right...
This is a simple microstrip Marchand balun that I am trying to adapt to 1.8 GHz f0.
I connected a loop to the Balun balanced terminals to act as an antenna.
I know that a one wavelength loop in free space should have an impedance of around 100 ohms, and the balun is a 1:1 50 ohm design (based on "a new planar Marchand balun design"), so it is not matched. it's basically just a test.
And also, it is not a perfect loop since the balun terminals are somewhat spaced.
The problem I have is a really low real impedance (0.04 ohm), while the imaginary part is 14 ohms.
I designed the balun using DesignSpark and converted from Gerber to DXF using Diptrace.
The excitation comes from a lumped port with a dummy box at the side of the PCB. HFSS says that it is connected to only one conductor. I wonder if it is because of bad geometry or because the ground plane and the balun arms are shorted to ground by pins (by design, altough the unbalanced center conductor is not shorted to ground)
the port box seems to touch both ground plane and microstrip center conductor.
I'd appreciate any help.
HFSS 13 file attached