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Antenna modelling with EZNEC Pro/2 v7.0


Mounting antennas on different bands i same mast

2m, 6m on same mast and ground gain angle on different height for 6m antenna 

70cm, 2m and 6m in same antenna mast including the impact of mounting hardware 

Current antennas at SM4GGC

All elements are in free space

Antenna boom or other metal structure for mast or mounting hardware is not in the in the calculation


The degradation seems to be on the highest frequency in this case 70 cm and stacking vertical has a bigger impact then horizontally with the antennas side by side.

The square stacking 2m with 70cm inside seems to surprise me with good result.


Ref ant. 2m YU7EF EF0213M Gain 16,1 dBi

Ref. ant 70cm YU7EF EF7027 Gain 19,50 dBi


 First case is a 2m antenna close to 70 cm in vertical stacking.

Fästpunkt 1
Yu7EF 1302M andYU7EF 27el_layoute.jpg
V-stack 175_350_700 kopiera.jpg

Second case is 2m antenna close to 70 cm side by side

YU7EF_EF1302M_Tona21 432 sida sida layoute.jpg
AZ-stack 800_1200. kopiera.jpg

Third case 70m and 2m in square stacking 

Ref ant. 2m YU7EF EF0213M stacking 4x4m Gain 21,96 dBi

Ref. ant 70cm YU7EF EF7027 stacking 2x2m Gain 25,32 dBi

*No loss was noticed on 2m besides the stacking loss for shorter stacking distance

4X13el and 4X27el_layoute.jpg
4_stack_144_432_3000X3000 kopiera.jpg
Fästpunkt 2

Degradation of 2m at distance between 6m and 2m Yagi 1m=0.61dB 1.5m=0.31dB 2m=0.16dB 2.5m=0.02dB.

Note there is no degradations on 6m

Diagram of 2m:

Black=only 2m antenna

Blue=6 and 2m antenna with distance 1m

6m and 2m_layoute.jpg
AZ diagram.jpg

6m antenna at different heights above ground with Ground Gain tabs in Elevation

Black = height 2m above ground, angle 25 degrees

Blue = height 5 m above ground angle 15 degrees

Green = height 10 m above ground, angle 8 degrees

2_6_10m höjd1.jpg

15 m above ground, angle 6 degrees

Optimal angle for ES jump 1400 km to 1600 km is about 6-4 degrees

20 m above ground, angle 4 degrees

At higher altitudes, the number of flaps increases and the elevation appears to level off at 2 degrees

15m höjd1.jpg
20m höjd1.jpg

I have done some more simulations on an antenna configuration with 6m to 70cm that I mounted in my mast. In the simulation, all antenna booms and metal parts in the antenna frame are included in the simulation.


The radiation patterns are affected by the metal construction and surrounding antennas but perhaps not as much as you might think. Degradation of gain is at most in 2m with about -0.5 db, 70cm and 6m have a couple of tenths of a degradation if compared to theoretical antennas set up in free space without any metal structure and antenna booms

Fästpunkt 3

50 MHz

Outer ring 13.54 dBi Max gain 13.4 dBi Degradation -0.14 dB due to influence from other antennas and mounting equipment

Current antennas at SM4GGC

Fästpunkt 4

144 MHz

Outer ring 21.62 dBi Max gain 21.07 dBi Degradation -0.56 dB due to influence from other antennas and mounting equipment

432 MHz

Outer ring 25.39 dBi Max gain 25.01 dBi Degradation -0.38 dB due to influence from other antennas and mounting equipment

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