50Ω Direct Feed Low Q Low Noise Yagi Design


8 element CQM8DXZ 2M (144MHz) 1.78λ...

CQM8DXZ in 4nec2

CQM8DXZ

 

CQM8DXZ AOWA (no bent elements required) designed in June 2018 takes into consideration all of my work over the past seven years.

It is exactly the same boom length as Hartmut's DG7YBN / 144 MHz / GTV 2-8w. Whilst VSWR bandwidth and average Q-factor has almost the same shallow gradient, G4CQM's CQM8DXZ is superior when located in a noisy urban/residential environment!

DL6WU stacking distances are somewhat less than Hartmut's GTV 2-8w design, another clear advantage! However, using optimal stacking distances CQM8DXZ gets even better!...

 

Average Q-factor comparison: CQM8DXZ (left) Vs GTV28W (right)
CQM8DXZ Q-factorGTV28W Q-factor

 

DL6WU stacking distances for CQM8DXZ...
DL6WU stacking distances are slighty less than Hartmut's GTV 2-8w design...

 

Vertical Plane
Vertical Plane
Gain and F/B Vs F/R
Gain and F/B Vs F/R

 

SWRHorizontal Plane
CQM8DXZ SWRCQM8DXZ Horizontal Plane

 

Using DL6WU stacking distances!
CQM8DXZ residential in AGTC LITE4 x CQM8DXZ residential in AGTC LITE
CQM8DXZ residential in AGTC LITE4 x CQM8DXZ residential in AGTC LITE
4 x CQM8DXZ in TANT
T_sky = 200 K -- T_earth = 1000 K
4 x CQM8DXZ in TANT
T_sky = 287 K -- T_earth = 5126 K
4 x CQM8DXZ in TANT - T_sky = 200 K -- T_earth = 1000 K4 x CQM8DXZ in TANT - T_sky = 287 K -- T_earth = 5126 K

 

Using optimal stacking distances!
4 x CQM8DXZ in TANT
T_sky = 200 K -- T_earth = 1000 K
4 x CQM8DXZ in TANT
T_sky = 287 K -- T_earth = 5126 K
4 x CQM8DXZ in TANT - T_sky = 200 K -- T_earth = 1000 K4 x CQM8DXZ in TANT - T_sky = 287 K -- T_earth = 5126 K

Optimal stacking distances (mm)

H = 2903.0000
V = 2338.0000

 

Antenna Files...

 

CQM8DXZ.nec
4CQM8DXZ.nec
CQM8DXZGNU.xls

 



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