[TowerTalk] Help in planning a new QTH

[Steve London]

 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