On 9/13/2019 5:38 AM, jimlux wrote:
I'm not so sure about the efficiency aspect for shorter antennas - sure,
for "very short", the matching network losses will increase, but the
actual antenna efficiency isn't different (I^2*R losses are usually
pretty low)
There are (at least) two important dimensions related to gain of a Yagi.
One is the length of the elements. The other is boom length, and it is
well known that boom length is strongly correlated to forward gain. When
I said "compromised dimensions" I was talking about both. This link is
to an Excel spreadsheet that summarizes the performance of VHF Yagis.
Note that the sort is by boom length, and the strong correlation to
gain. http://www.bigskyspaces.com/w7gj/VE7BQH%20Charts.xls The
spreadsheet will display well in alternative spreadsheet programs like
Open Office, Libre Office, and Google Sheets.
And, of course, as others have noted, there's the matter of the
bandwidth of the gain as well as the beamwidth. The spreadsheet also
includes this data.
73, Jim K9YC
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