Below is a report on the Avanti AstroPlane antenna done back in the days. I posted some numbers, and some Internet exhibits that claims Avanti professionally tested their AstroPlane (A/P). I did this just for a little history on the AstroPlane. I have documents and posted below 2 Eznec models that tend to support Avanti claims...who did the tests, and how it was done. I also provide some verification information on the author of the test report. i studied the details of this report and tried to follow the ideas for their construction, so that I could try and duplicate their results. So, this is what I hope these models will show us. I scaled an old Asto Plane model to 144 Mhz. I started with a model that had a full 1/4 wave radiator. I did this for my convenience in modeling. IMO these 2 models tend to support much of what Avanti has claimed in their advertising. In the PDF files below is the Avanti's AstroPlane test report, an old ad I found in CB Magazine. I found the Technology News report talking about the Engineer Avanti used to do this research. Followed by the 2 models in the PDF file posted below. Sorry for the poor copies, working with old copies of copies is tough. If you can't see something clearly...try using the PDF print. The Zoom functions might help improve the images. Models: AstroPlane at 144 MHz set 72" inches to the feed point (1 wavelength high - see the report). 1. shows the antenna model in Free Space (FS). This means all the ground and wire resistance effects for the model have been removed. This is basically done so we can test the accuracy of the model. See the 1st page of each model, the Eznec Control Panel. At the bottom it shows the Average Gain results (AG). AG results show 1.662 = 2.21 db. In this case the 2.21 db value after the = is a correction value for the gain and is due to an overstated or understated in gain, reported as an error for the model. If the value -2.21 db was noted with a (-) then the gain is understated. Then we would add this value to the gain reported by the model. Then, this is consider as the accurate gain for the model. If the value 2.21 db, as stated for this model with a (+) that is blank, the gain is overstated and we would subtract the value from the gain reported by the model. Then can consider this is the accurate gain for the model. 2. shows the antenna over the Eznec feature for Real Earth. This simply means the opposite of FS, where the losses were removed. Depending on the sign (+ -), just add or subtract 2.21 db to the gain reported for these 2 models and we will see the accurate gain that the model should report. IMO, none of this means the A/P is bad, weak, a dummy load, or is deficient. It is a great antenna and better in other ways that only a few will likely acknowledge. Make your own conclusions about the likely gain for the AstroPlane as reported by Avanti advertising and by others making knockoffs of the great vertical 1/2 wave antenna design.