How to Add Objects to Dia Diagram Editor

Question

I am trying to draw diagrams similar to the attached (radio signal/antenna layouts and configurations, in case the image doesn't post). I am using Dia Diagram Editor (if there is a better option, I am all ears). I am trying to use the objects located on this page: http://dia-installer.de/shapes/electronic/index.html. Radio/Antenna Configuration

I have used the auto-installing tool which doesn't include this sheet. I have followed the instructions to put it in the "Dia" folder. I have tried multiple avenues and each time I re-open Dia hoping the shapes are added, they are not. I am not even sure these are the shapes I need, I just want to make sure that when I find the right ones, I can install them for use. Thank you in advance for any help and guidance!