Hi,
I would like to pose a question regarding the design of a Log-Periodic Antenna configuration which I have defined as a multiport network, as described in the relevant example of the FEKO User Guide. For the improvement of a specific characteristic of the antenna (narrow band gain response), I have introduced R-L parallel loads in some of the ports, which have been defined as in the first image I attach. Although this works as expected in this simple model, I would like to also confirm the result in a more complex model where the log-periodic antenna boom is implemented as 2 parallel rectangular conductors providing the desired Z0. In this case, I thought that the equivalent circuit would be to connect the 2 conductors at the height of the dipole of interest with a wire, define a port and the use the same load as in the transmission-line (TL) model. That does not seem to work properly though. The only way I could imitate the performance of the TL model was by defining 2 ports, calculating the 2x2 S-matrix of the R-L circuit and loading it as a touchstone file in a general network element (second image, right, there are 2 conductors although they cannot clearly be seen because I wanted to show the ports).
My question is, why does this distinction exist in the more complicated model? Shouldn't there be a voltage drop on a wire connecting 2 points when a load has been defined on its corresponding wire port, or is the electrical connection preserved and the R-L load is "branching out", as I depict on the left of the second image? That would mean I might have to modify other models too, so I would like to clearly understand how the load works.
Thank you,
George
