|
The hat used in these tests was the
DX
Engineering Hot Rodz system.
| Type |
Height Base |
Top Length |
Hat dia |
Field Strength |
Frequency |
Relative FS |
|
| Reference |
|
|
-18.5 |
|
|
best tested antenna |
Large
air |
36″ |
84″ |
0 |
-18.50 |
7.2 |
0.00 |
3″dia #12 |
| Large Air |
36′ |
27″ |
47″ |
-18.70 |
7.2 |
-0.20 |
3″ dia #12 47″ hat |
| Small air |
36″ |
27″ |
47″ |
-19.90 |
7.2 |
-1.40 |
1.5″dia #16 47″ hat |
| TarHeel |
42″ |
27″ |
47″ |
-21.00 |
7.2 |
-2.50 |
Tar with 47″ dia |
| TarHeel |
43″ |
84″ |
0 |
-21.10 |
7.2 |
-2.60 |
Tar with 7′ whip |
| RM-20 |
36″ |
27″ |
52″ |
-21.20 |
7.2 |
-2.70 |
Hustler RM-20 on 40m |
| TarHeel |
43″ |
27″ |
23″ |
-22.00 |
7.2 |
-3.50 |
Tar with 23″ dia |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| TarHeel |
61″ |
84″ |
0 |
-19.80 |
3.5 |
|
|
| TarHeel |
59″ |
27″ |
47″ |
-19.70 |
3.5 |
|
47″ DXE |
The most striking things are:
- The range between the best and worse system was
only 3.5dB
- A large hat at the TOP of the antenna allows
considerable shortening with no loss in efficiency
- For a given height antenna, efficiency is
increased with a hat at the top
Mobile and Loaded Antenna
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