160 meter or 80/160 Dual Band CCD

The dual band CCD design is possible on 80 and 160 meters. Patterns are the same as the higher frequency designs when mounted above the ground the same height in wavelengths. In other words this antenna mounted at 200 feet on 160 meters should have about the same pattern as a 20/40 on 40 mounted 50 feet high. However the bandwidth is not as good. Here are the theoretical SWR curves for a 80/160 dual band design mounted in a 120 degree inverted V with the apex at 125 feet:

160 meter SWR

80 meter SWR

As you can see it covers an impressive three quarters of the 160 meter band at under 2:1 but both the bandwidth and the lowest SWR is real poor on 80 meters. The 160 meter performance is the same for a 100 foot high flat top. The 80 meter performance is a little better when mounted flat top.

And before you ask it is near impossible to tune a CCD after it is built. You might get good results on one band or another by pruning or lengthening the last wire segment but you will invariably throw off the other band.

I don't really consider this a good dual band design. So if you really want to talk us into making you this antenna here are the caveats:

• We can only guarantee that it will have its SWR dip somewhere in the 160 meter band. We will not be able to target a particular part of the band. Normal manufacturing tolerances might cause the low SWR point to shift from unit to unit.
• You might have to use a tuner on all or portions of the 160 meter band depending on your transmitter's SWR tolerance. The SWR should be low enough across the entire band that the feed line loss at this low frequency will be quite small even when fed with a tuner at the radio end and coax.
• We can't guarantee the second dip will even be in the 80 meter band let alone target a specific portion of it. Only if you are lucky you might be able to get good results with it on 80 meters. A tuner will definitely be required.
• You need to mount it at least 125 feet high if in a V and 100 feet high if mounted flat top. Mounting it lower than this will result in a higher SWR. Mounting it higher will improve the SWR and lower the take-off angle but move the dip up the band slightly.

 Send your request to Dave Kelley ai7r@ccdantennas.com.