Homemade Gray-Hoverman antenna - design and model

I recently designed and built a homemade antenna for TV reception.  The design is called a Gray-Hoverman.  The idea behind this antenna is to replace my existing Channel Master 4-bay antenna (CM4221).  There is nothing wrong with the Channel Master antenna, mainly I'm just curious if I can construct a better antenna.  That's the type of nerd I am. :)

To design the antenna I used a free piece of software called 4nec2, which allows you to design and model (or predict) how the antenna will perform.  I also used some python scripts to optimize the design.  I'll include links to all the software below.  I'm not going to go into the details on antenna modelling and the use of 4nec2 as it's a very complicated subject that took me a while to learn.

The Gray-Hoverman design I came up with is optimized for my specific area.  The TV channels in my area that I care about are 15, 16, 19, 24, and 31.  So my design is optimized just for this range.

Here's the actual NEC file.  Feel free to download, use, modify, etc.  If you're interested in building this model, I suggest using this file and 4nec2 to get the exact dimensions of each element.

CM D--EVAL --num-cores=2 --uhf
CE
SY GAP=0.086
SY RAD=0.003175
SY FRAD=0.00229
SY SRAD=0.00635
SY SX=0.121
SY SY=0.642
SY SZ=0.054
SY COND=2.0e7
SY L=.1629
SY W=0.109
GW    1    1    0    -GAP/2    0    0    GAP/2    0    FRAD
GW    2    11    0    GAP/2    0    0    GAP/2+L    L    RAD
GW    3    11    0    GAP/2+L    L    0    GAP/2    2*L    RAD
GW    4    11    0    GAP/2    2*L    0    GAP/2+L    3*L    RAD
GW    5    4    0    GAP/2+L    3*L    0    GAP/2+L+W    3*L    RAD
GW    6    11    0    GAP/2    0    0    GAP/2+L    -L    RAD
GW    7    11    0    GAP/2+L    -L    0    GAP/2    -2*L    RAD
GW    8    11    0    GAP/2    -2*L    0    GAP/2+L    -3*L    RAD
GW    9    4    0    GAP/2+L    -3*L    0    GAP/2+L+W    -3*L    RAD
GW    10    11    0    -GAP/2    0    0    -GAP/2-L    L    RAD
GW    11    11    0    -GAP/2-L    L    0    -GAP/2    2*L    RAD
GW    12    11    0    -GAP/2    2*L    0    -GAP/2-L    3*L    RAD
GW    13    4    0    -GAP/2-L    3*L    0    -GAP/2-L-W    3*L    RAD
GW    14    11    0    -GAP/2    0    0    -GAP/2-L    -L    RAD
GW    15    11    0    -GAP/2-L    -L    0    -GAP/2    -2*L    RAD
GW    16    11    0    -GAP/2    -2*L    0    -GAP/2-L    -3*L    RAD
GW    17    4    0    -GAP/2-L    -3*L    0    -GAP/2-L-W    -3*L    RAD
GW    18    30    -SX    -SY/2    SZ    -SX    SY/2    SZ    SRAD
GW    19    30    -SX    -SY/2    SZ*3    -SX    SY/2    SZ*3    SRAD
GW    20    30    -SX    -SY/2    SZ*5    -SX    SY/2    SZ*5    SRAD
GW    21    30    -SX    -SY/2    SZ*7    -SX    SY/2    SZ*7    SRAD
GW    22    30    -SX    -SY/2    -SZ    -SX    SY/2    -SZ    SRAD
GW    23    30    -SX    -SY/2    -SZ*3    -SX    SY/2    -SZ*3    SRAD
GW    24    30    -SX    -SY/2    -SZ*5    -SX    SY/2    -SZ*5    SRAD
GW    25    30    -SX    -SY/2    -SZ*7    -SX    SY/2    -SZ*7    SRAD
GE    0
LD    5    0    0    0    COND
GN    -1
EK
EX    0    1    1    0    1    0    0
FR    0    17    0    0    476    6
RP    0    1    73    1510    90    0    1    5    0    0
EN

The big question is - after construction, how did it perform compared to the Channel Master antenna?  I mounted each antenna in the same location and used my TV to scan for all channels.  For each digital channel (including those beyond what I care about) I wrote down the average signal strength.  My TV reports two signal numbers, the overall signal level in percentage, and the signal-to-noise ratio in decibels.  For both numbers, higher is better.

Channel	CM4221	Gray-Hoverman
15	98% (32db)	98% (33db)
16	89% (26db)	89% (27db)
19	56% (15db)	43% (12db)
24	95% (29db)	98% (30db)
31	84% (25db)	84% (25db)
34	89% (27db)	92% (28db)
41	87% (26db)	89% (27db)
50	98% (32db)	98% (30db)

As you can see, the Gray-Homerman antenna matched or exceeded the Channel Master for almost all channels, even some beyond what the antenna was designed for.  Only at channel 50 was the Channel Master better.  [I'm ignoring channel 19 because that channel is weak and anything below 60% and my TV cannot lock onto the signal.]

Here is a youtube video I uploaded showing design and construction of the antenna.


Here are download links useful to antenna modeling:
4nec2 - http://www.qsl.net/4nec2/
nikiml's python scripts - http://clients.teksavvy.com/~nickm/scripts.html
Optimized versions of the NEC2 engine - http://users.otenet.gr/~jmsp/