Thread: Rca ant751
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Old 23-May-2017, 9:07 PM   #48
ADTech
Antennas Direct Tech Supp
 
Join Date: Jan 2010
Posts: 2,784
I finally should be able to upload a summary plot of the relative boresite reception of a number of small Yagi/LPDA antennas from my testing earlier this month.

A few notes to ponder while you're waiting:

1. I'm not terribly happy with the quality of the data gathered. I identified, after the fact, a number of things that need improvement in my process including an huge signal "suck-out" (it will be painfully obvious) in the middle of the UHF band, probably due to an unwanted signal reflection or a fault with a cable or the transmitting antenna. I didn't find it until the range was broken down and I started pulling data into Excel for plotting. Since the anomaly is present for all of the antennas tested, it's still an equal playing field.

2. I did not have the opportunity to normalize the spectrum analyzer to the tracking generator (impractical), either before each measurement was made or via a correction file in the post-processing (didn't think of it) in order to smooth tracking generator non-linearities (up to +/- 2dB over sweep span) and other fast-changing (frequency-wise) impairments. If you know how to easily implement weighted average smoothing in Excel 2007, I'd be interested.... It would really clean up the presentation of the data.

The plot to be posted, once I finish tweaking it in the morning, is fairly congested with the data for seven antennas overlaid using Excel's default coloring scheme (ugh!). I haven't gotten around to changing the line style and color for better legibility and probably won't since this plot is a one-off from my normal analysis which normally compares ten different readings for each antenna done in a two-up comparison (Antenna A vs Antenna B).

I will say there are some interesting results to be seen.
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Last edited by ADTech; 24-May-2017 at 1:48 AM.
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