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Dual Band 2M / 70cm Yagi
On this page are designs for Dual Band 2M / 70cm antennas.  All antennas are 50 ohm designed driver.  These Yagis have a unique element called a ‘Open Sleeve’.  This is a director very close to the Driven Element (the Driven Element is sized for 2M).  When on 70cm the ‘Open Sleeve’ acts as part of the Driven element on 70cm (3rd harmonic of 2M).  These designs are from Martin Steyer DK7ZB from Germany.
I have chosen 4. 5, and 9 elements Dual Band Yagi. The 4 element Yagi has a Reflector 2M, Reflector 70cm, Driven Element, Open Sleeve (basically 2 elements on 2M and 2 elements on 70cm). The 5 element Yagi has a Reflector 2M, Reflector 70cm, Driven Element, Open Sleeve, 70cm director (basically 2 elements on 2M and 3 elements on 70cm).  See pictures of how I built a 5 element Dual Band beam using 1/2” PVC pipe and 1/4” copper tubing.  The 9 element Yagi has a Reflector 2M, Reflector 70cm, Driven Element, Open Sleeve, Director 2 - 70cm, Director 1 - 2M, Director 3 - 70cm, Director 4 - 70cm, Director 2 - 2M, (basically 4 elements on 2M and 6 elements on 70cm).
4 Element - Dual Band - 2M / 70cm - 50 Ohm 16 Inch Boom 6mm tubing - use 1/4” tubing
5 Element - Dual Band - 2M / 70cm - 50 Ohm 16 Inch Boom 6mm tubing - use 1/4” tubing
I made the 5 Element Dual Band Yagi using 1/4” copper tubing and 1/2” PVC pipe.  For the driven element I used a PVC ‘X’ and put plugs on each side, I then drilled a 1/4” hole for the tubing, on the side of the plug I drilled and tapped a 6x32 hole.  I also drilled a 1/4” hole in the center of the ‘X’ for the coax.  I measured the tubing and inserted it into the hole and tightened a brass 6x32 screw to hold the tubing.  I then soldered the coax to each side of the tubing.  I was petty tight with with the 1/2” PVC fitting.  If I was going to make another one I would use a 3/4” PVC pipe.  On each element I tapped a 6X32 hole and used a brass screw to hold the element in place. 
DK7ZB Dual Band 5 Element Yagi built from 1/4” copper tube.  (Element are slightly bent - it was dropped).  Notice the ‘Open Sleeve’ element, short element close to the Driven Element.  This allows the beam to radiate on 7cm.  Notice how close the element is. 
Close-Up of the Driven Element and the ‘Open Sleeve’ element.  The Elements are passed through the PVC pipe and are secured using a screw with a tapped hole  The Driven Element uses 1/2” PVC plugs with a 1/4” hole and the a screw to hold the element securely.  The coax is feed into a 1/4” and is terminated on each element.
9 Element - Dual Band - 2M / 70cm - 50 Ohm - 3.2 mm Tubing (use #8 AWG solid copper wire or 1/8” welding rod)