HY-GAIN SPT-500 or Tornado 27?

[Shockwave]

That doesn't make sense.... there are many who would attest that the Imax 2000 is just as good as the maco 5/8 or just barely down, at distances of 20-50 miles away. If the elevation angle of the radiation is so much higher on the Imax, shouldn't the imax not have anywhere near the local/regional range as the maco 5/8?

Perhaps if you removed or significantly shortened the radials on the SP-500 these things would make more sense after your observation. My comments were based on a 5/8 wave ground plane antenna and not an end fed fiberglass stick.

The Imax is not a 5/8 wave ground plane and because of this its matching network is designed to take the higher impedance that results without radials and transform it back down to 50 ohms. Its counterpoise is your coax and mast. This usually causes much more RFI problems then a ground plane.

This is why adding the radials does little to improve the gain on the horizon with an Imax. Although, you will gain a little decoupling from adding the ground plane kit and improve the RFI problem. You will also note the kit uses radials that are very short and on a sharp downward angle. They do that so it reduces the affect on impedance since the antenna is already designed to work without them.

 

[VA3ES]

The Imax 2000 is a compromised end fed stick, as Shockwave calls it. It may be 5/8ths w.l. long, but that lack of radials really compromises the performance. The radial kit that is provided for the Imax is merely a form of RF choke to help suppress the common mode currents that are present in that type of antenna. The short radials in that kit do nothing to help lower the radiation pattern.

In my honest opinion, all the Anttron antennas are a compromise and perform worse than any properly designed antenna, with full-size radials. Even the Sirio so-called 5/8ths w.l. use those ridiculous short radials, which leads me to believe that they are more like cmc chokes than proper radials.

After playing with vertical antennas for over 40 years, (both professionally and as an amateur) both experience and theory teaches that a proper 5/8ths w.l vertical needs proper 1/4 w.l. radials. In fact, I've learned that any vertical needs proper radials.

These end-fed sticks will work but must be raised very high to work well. My own SPT 500 performs better at 45 feet height, than my buddy's, Imax at 80 feet. Funny that.

And another friends own Maco V58 at 40 feet height performed better than his old Imax at 60 feet. That told us all we needed to know.