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Old 24-Jun-2017, 1:16 PM   #110
tripelo
Senior Member
 
Join Date: Jan 2010
Location: Dallas, TX
Posts: 127
Compare: Antennas Direct DB8e & CM-4228HD

(continued from previous post)

Part 4. Compare 6 antennas (DB8, DB8e, 4228, 4228HD, 91xg, HDB91x)

Having earlier measured four other high-gain UHF antennas relative to the HDTVi antenna, this could suggest that all six could be compared.

http://forum.tvfool.com/showpost.php...2&postcount=99

The main link between the two data sets is the measurements of the HDTVi antenna. The HDTVi was used as a reference antenna in both experiments. Realizing that errors can accumulate, a direct comparison of the two data sets might be somewhat useful.

Below is an image that shows the other four antennas compared directly with the HDTVi antenna:





The Yagi antennas (91xg and HDB91x) stand out as having higher gain as the channel number increase. The two Yagis appear to have the highest gain available at the top of the UHF band.

It appears that the older CM4228 (non-HD) is a fairly good match to the newer DB8e, both show a wideband response with relatively high gain at the lower channels.

If the above graph were accurate for every channel (which is doubtful), one could add the gain of the HDTVi to every antenna, to obtain a total gain figures. Previous calculations show the gain of the HDTVi to be about 6.5-7 dBi.

Caveat: Keep in mind that real antenna gain patterns are rarely (if ever) linear, and the above chart (although based on measured data) is an approximation.

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Attached Images
File Type: gif DB8e, 4228HD, & Others.gif (11.4 KB, 3375 views)
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