| Split Dipole | Folded Dipole | LFA Loop | V Split Dipole |
|---|---|---|---|
| | | |
Updated 22-02-2018... G4CQM's Dipoles Explored blows a hole wide open in myths propagated on the Internet concerning the pros and cons of particular driven elements!
To create a level playing field the following analysis has been carried out in K6STI's Antenna Optimizer Professional (AOP) version software. AOP is perfect for analysis of loops and bent elements! Each dipole has been tuned for minimum reactance at 144MHz. Segmentation has been set at 25 segments per λ/2 in all examples. The Split Dipole, Folded Dipole and LFA Loop all exhibit their own respective intrinsic impedance...
Meanwhile the V Split Dipole can easily be adjusted to 50Ω by simply changing the swept back angle and tuning out reactance by altering length!
Note that the LFA Loop and V Split Dipole exhibit some pattern distortion (not symmetrical) which has an impact on the final overall pattern when located in a yagi build, LFA Loop being worst of all!
Integration and the working of each of these different dipole types into a yagi build is complex. Mutual coupling occuring between elements and subsequent loading effects will impact on resultant intrinsic feed impedance in a positive or negative way! This is dependent on the tuning regime of all the parasitic elements along with the driven element which also determine the polar pattern in both E & H planes, and over the desired operational bandwidth.
Radio Amateurs may be seduced by marketing speak into the benefits of a particular system. However, the reality is that all of the different feed systems are in one way or another a compromise, no one system is perfect, so don't be taken in by boastful claims!
At the end of the day it may well come down to ease of construction!
Also see: BALUN and G0KSC 2M 8LFA Reality Check!...
Click on images for full size view, opens in new window!
| Split Dipole |
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| Split Dipole in AOP | Antenna File - Symbolic Dimensions |
|---|---|
 |  |
| Azimuth | Elevation |
 |  |
| Split Dipole - Average Q-factor = 4.9 |
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| Split Dipole - SWR |
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 |
Click on images for full size view, opens in new window!
| Folded Dipole |
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| Folded Dipole in AOP | Antenna File - Symbolic Dimensions |
|---|---|
 |  |
| Azimuth | Elevation |
 |  |
| Folded Dipole - Average Q-factor = 3.2 |
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| Folded Dipole - SWR |
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 |
Click on images for full size view, opens in new window!
| LFA Loop |
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| LFA Loop in AOP | Antenna File - Symbolic Dimensions |
|---|---|
 |  |
| Azimuth | Elevation |
 |  |
| LFA Loop - Average Q-factor = 2.5 |
|---|
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| LFA Loop - SWR |
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 |
Click on images for full size view, opens in new window!
| V Split Dipole |
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| V Split Dipole in AOP | Antenna File - Symbolic Dimensions |
|---|---|
 |  |
| Azimuth | Elevation |
 |  |
| V Split Dipole - Average Q-factor = 7.1 |
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| V Split Dipole - SWR |
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Flag Counter started on September 14th 2017...