From Dave Hachedorian's (K6LL) posting:
> Once you do the conversions, the claimed
> gain is as follows:
> Band 4el Steppir C31XR
> 20 9.5dBi 8.1
> 17 10.0 -
> 15 10.2 8.4
> 12 10.4 -
> 10 10.6 9.5
Those Steppir gain figures are very questionable. They are significantly
higher
than the gain figures for optimized yagi designs in the 20th edition of the
ARRL
Antenna Book. While a Steppir may be a fine antenna, it's still just 4
elements
on each band, and won't be any better than an optimized 4 element beam on the
same boom length.
For another comparison:
Band Optimized 4-element from ARRL Antenna Book
20 8.5 dBi (26 foot boom)
17 8.5 dBi (20 foot boom)
15 8.2 dBi (18 foot boom)
12 8.5 dBi (15 foot boom)
10 8.3 dBi (14 foot boom)
Now, you could argue that the Steppir has the 4 elements on a longer boom, so
let's compare to an optimized yagi with approximately the same boom length:
Band Optimized N-element yagi from ARRL Antenna Book
20 9.2 dBi (34 foot boom, 5 elements)
17 9.8 dBi (30 foot boom, 5 elements)
15 10.8 dBi (36 foot boom, 5 elements)
12 10.8 dBi (30 foot boom, 6 elements)
10 11.6 dBi (36 foot boom, 6 elements)
I would have to conclude that the Steppir manufacture's gain figures are
inflated on 20 and 17 meters. I would also question the higher bands - when I
get a chance I'll have to model 4-element optimized yagis for 15, 12 and 10
meters on 32 foot booms and compare to the Steppir claims.
By the way, I have done my own modeling of the C31XR vs. optimized yagis. The
model and results are at http://n2ic.topcities.com/c31xr/c31xr.htm .
73,
Steve, N2IC
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