Discussion Forum

Dear Sir/Madame,

I am new to Comsol Multiphysics and I am having difficulties with the lumped port/element boundaries from the Electromagnetic Waves, Frequency Domain physics section. I recreated the Log-Periodic Antenna from the RF module. I got this to work just fine using the manual from comsol. Now I wanted to play around with this and change the antenna material to aluminum instead of the PEC boundaries (similar to real life antenna's).

To do this I got rid of the last difference operation as specified in the step by step guide (which I attached for convenience). Now instead of having only 2 domain elements we have multiple. In the original file all domains had the material selected as air and the antenna had PEC boundaries. Instead I now chose aluminum and selected all antenna domain elements.

In my head the lumped parts are now in between two conductive boundaries (aluminum instead of PEC), yet when trying to solve the study step Comsol gives the error: "Uniform lumped port should be placed between two conductive boundaries. - Feature: Type: Lumped Element Tag: lelement1 Operation: LumpedElement (lelement1) - Feature: Type: Lumped Port Tag: lport1 Operation: LumpedPort (lport1)".

So I am probably missing something. In an attempt to solve the problem I tried to reapply the PEC BCs at all boundaries (just for the sake of checking), yet this gives the same error. Perhaps i am making a rookie mistake or there is an easier way to create an aluminum antenna. All help is sincerely appreciated

Thanks in advance, Gijs Mast

Ps. I included: 1. The comsol manual to a log-periodic antenna 2. a figure which shows the location of an lumped element in between the aluminum domain elements of the antenna. 3. A comsol mph file which contains my attempt to solving this problem