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This chart helps select the right GAP antenna. When comparing GAP's bandwidth is not a concern. With few exceptions, a GAP yields continuous coverage under 2:1 for the ENTIRE BAND.
All antennas utilise a GAP elevated asymmetric feed. A major benefit is the virtual elimination of the earth loss, so more RF radiates into the air instead of the ground. This feed is why a GAP requires
NO RADIALS. Just as elevating a GAP offers no significant improvements to its performance, adding radials won't either, making set up a breeze.
A GAP antenna has no traps, coils or transformers.
This is important. The greatest sources of failure in multi-band antennas are these devices. Perhaps you heard someone discuss a trap that had melted, arced or became full of water. Improvements to these inherent problems are the focus of the antenna manufacturer, while the basic design of the antenna remains unchanged.
GAP improved the trap by eliminating it! Removing these devices means they don't have to be tuned and, more importantly, won't be de-tuned by the first rain or ice. The absence of these devices improves
antenna reliability, stability and increase bandwidth.
Another major advantage to a GAP antenna is its NO tuning feature. Screws are simply inserted into pre-drilled holes with a supplied nut-driver.
The secret is out and people in the know say:
CQ - "The GAP consistently outperformed base-fed antennas and was quieter".
73
- "this is a real DX antenna, much quieter than other verticals".
RF
- "To say this antenna is effective would be a real understatement. Switching back and forth on 40m between another multi-band HF vertical and the GAP, there was no comparison. Signals were always stronger on the GAP, sometimes by 5 units, not just DBs".
Worldradio
- "These guys have solved the problem associated with verticals. That is, an awful lot of RF is wallowing around and dropping into the dirt instead of going outward bound. A half-wave vertical does need radials if it is end-fed (at the bottom). But the same halt-wave vertical does not (as much, hardly at all) if is fed in the centre".
IEEE
_ Near field and power density analyses show another advantage of this antenna (asymmetric vertical dipole); it decreases the power density close to the ground, and so avoids power dissipation in the soil below it. The input impedance is very stable and almost independent of ground conductivity. This antenna can operate with high radiation efficiency in the MF AM standard broadcast band without the classical ground plane, so as to yield easier installation and maintenance".
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