Here is a design for a 6ft rover yagi for 1296 Motorcycles.  It was designed to be small, light-weight, and still have good gain.  The prototype was built and found to exhibit about 18dBi.  The driven element is a folded dipole, using a .040 diameter wire as the fed portion.  A 4 to 1 balun made from .085in diameter hardline is used to transform the 50 Ohm coax to the feed point impedance.  I suspect a larger diameter fed portion of the driven element can be made to work, but I have not taken the time to match it up using this approach.  Matching 1296 yagis can be challenging, but this design comes close to 50 Ohms, using a 4:1 balun.

All elements are made from .125in diameter aluminum rod.  The elements are shorted to the boom by drilling  holes about .120 diameter, and driving the elements thru, using a piece of wood to protect the element ends, and a hammer.  Contrary to popular opinion, this technique works quite well, but it does take some time to get all elements centered.  If you plan to leave the yagi outdoors for any length of time, you should paint the structure using epoxy-based paint to preserve the low resistance contact of the elements to the boom.  All elements should be cut to within .005in, which is not hard using a 6in caliper, and a file.

The 2nd column from the left is the element position along the boom, and the final length is found in the right-hand column.  The "Half" and "Full" columns of data are just free space dimensions, and can be ignored.  The right-hand column represents the final element lengths, including the required boom correction.

It is necessary to "chamfer" the ends of the elements using a file, so that they are not square.  Shoot for a 45 degree angle, and take off about .020 to .030 on the bevel.  This reduces the "fringing capacitance" of the element ends, and helps keep the antenna on the correct frequency.  At 1296, it doesn't take much to screw things up.  The theoretical gain for this design is 18.5 dBi, as modeled using NEC2. (that's within spitting distance of a 45el looper).  Don't get me wrong, the extra 1.5dB gain of the looper will become very noticeable when working weak signals...but remember, you wanted to keep it small.  You can't stash a loop yagi in your trunk easily without messing it up pretty good.  Rod yagis also survive the perils of roving near tree branches better than loopers.

One of the biggest problems making home-brew yagis is that of drilling the boom.  First, get a piece of angle stock aluminum, about 0.5in on a side.  You can use this to carefully scribe a straight line down the length of the boom.  Using the spacing data from the 3rd column, mark the boom using a 6-in caliper.  Don't worry about measuring the distance from the reflector...just mark of the element spacings as you go.  Yagi performance is much more dependent on element spacings (inter-element coupling) than on exact element position.  A metal caliper can scribe a line on the boom in each element's position, intersecting with the lengthwise scribed line, as you measure off the element spacings. After the element positions are carefully marked, center-punch the locations for the elements on one side.   I made 2 aluminum blocks that slide over the boom, and tapped them for a 6-32 screw.  The screws are used to hold the boom in-place so it doesn't rotate.  The blocks are then slid down the boom as you drill, and re-tightened at each position.  Make sure that the lengthwise scribed line running down the boom is aiming straight up.  If you can manage it, installing the element on the end of the boom will provide a decent indication of proper boom rotation.  This will insure that your element holes are in the center of the boom.  Even if you're off a little, the yagi will still work well, but try to be precise.  Moving only 1 block at-a-time, the boom doesn't rotate, and all the holes come out parallel.  Try to keep the blocks fairly close together as you drill (about 6-8 in.) so the boom doesn't flex too much.  Take your time, and you will wind up with a nice performing 24 element rover-yagi for 1296.  It takes a few hours of labor, but the price is right.  Commercial antennas are just too expensive, and many don't work as well as this one, per boom length.  If you really want to be compact, you can cut the boom in the middle, and use a piece of tubing to splice the 2 halves together.  Now you have one less excuse to avoid going out roving on 1296.

Don't forget that 1296 antennas cannot work if you put your antenna support mast through the plane of the elements.  This antenna must be supported at the top of your mast, or performance will suffer.  Try to keep horizontal U-bolt segments at least 6 inches or more away, to avoid de-tuning.

73 es Cu on the band!

W3IY/R