Mirrored-J - Triple Height, Side Mounted, J-Pole
Also known as the Mirrored Copper Cactus.
The Mirrored-J has become one of the most favored antennas among 6-meter enthusiasts who often work both ends of the band, but the antenna works equally as well on 2-meters and other bands.
Its popularity on 6-meters is primarily due to its ability to be turned either vertical or horizontal quickly, which alters the impedance just enough to change its frequency into the desired range of operation for horizontal or vertical contacts.
Using only a simple Solenoid and a couple of screen door springs wrapped around the horizontal mounting tube, the orientation may easily be remotely controlled
The perfect antenna for those with limited real estate remaining on their towers. The Mirrored-J easily mounts from gable ends, eaves, virtually anywhere not already consumed by the rest your antenna farm.
You asked for it, so here it is!
My ever popular Mirror-image J-Pole Design.
The Mirror-image J-Pole is very easy to construct and requires only two T-Fittings plus a length of copper pipe, for the actual antenna itself.
To visualize the antenna, one must only picture 3 half-wavelength verticals end to end and 2 quarter-wavelength verticals, also end to end, positioned only a few inches away from and centered on the side of the taller vertical.
Construction of the mirror-image J-Pole is accomplished by starting with two T-Connectors separated by the distance shown for the band of choice.
For two meters the space between the two vertical pipes should be 2 inches.
Two vertical pipes (a long and a short) will point upwards and two vertical pipes (a long and a short) will point downward from each T-Connector.
The tall vertical pipes are affixed to one T-Fitting (one each side of this fitting) and the short vertical pipes are affixed to the other T-Fitting in like fashion. The tall vertical pipes are of the length shown as the Overall Length on the plans for the Copper Cactus. For 2-meters this distance is 58 inches to the centerline of the T-Fitting or an overall antenna length of 116 inches (which is THREE half-wavelengths overall).
The short vertical pipes form the tuning stubs and are the length shown as the Stub Length on the plans for the Copper Cactus. For 2-meters this distance is 19-1/3 inches to the centerline of the T-Fitting or an overall stub-length of 38-3/4 inches. The nice thing about the mirrored-J is that mistakes in measurements up to 2 inches on the long vertical and 1/2 inch on the tuning stub, will not affect the performance or SWR of the antenna.
The 2-meter Mirrored-J is mounted on the end of 1-1/2 inch PVC pipe about 5 or 6 feet long. The PVC pipe is mounted horizontally from your tower or roof gable. The tall vertical pipe of the antenna is slid through a comperable size hole drilled into the side of the PVC at the end. A PVC T-Fitting may be sawn in half and used as a saddle to mount the antenna to round vertical masts, such as push-poles.
The antenna itself sits vertically. The coax is connected as per the instructions on the Copper Cactus plans to the upper vertical and tuning stub. On this particular antenna, the center conductor of the coax should go to the tall vertical and not to the tuning stub as in normal J-Pole construction. As always, keep the center conductor of the coax as short as possible, lengthening only the shield if necessary, using copper wire.
For Safety, the shield of the coax should be grounded to earth ground before entering your shack.
TTUL - 73+ de Gary - KGØZP