K7RAW NOODLE-TENNA

SOMETHING FOR THE WEEKEND SIR?

One of the reasons I like Ham Radio so much is the experimentation side - in particular, antennas. I'm only an M7 Foundation License holder with very limited knowledge of antenna theory, so it's always nice when you find someone who's come up with a nice little project that is simple and easy to construct and play with.

One such person is Rudi (K7RAW), who came up with a super simple weekend project based on those light foam Pool Noodles. Very simple to make and lots of scope to make variants. Watch the video and give it a go - it's fun!

Click on image for video

This is a BRAND NEW type of HF antenna for those with extremely limited space to setup a conventional antenna. It is derived from the Slinky Antenna but with a few upgrades. It is less than 1/5th the length of a normal dipole, yet performs similarly. No ground, radials, counterpoise, tuner or BalUn required. Just a coax feedline with a Mix 31 common-mode ferrite choke at the antenna end.

It uses widely available ordinary parts which cost less than $25. It is easily scalable for other HF bands and can be used in vertical or horizontal mounting, including with other NoodleTennas on the same mast, acting like a fan dipole.

On 10m the bandwidth is about 600 KHz below 1.5 and about 1 MHz below 2.0 I've made many contacts with it, getting good signal reports. You can build one in about 2-3 hours. MATERIALS: (scale the lengths for other HF bands) 3" diameter (large type) 50" long pool noodle 40" of 3/4" schedule 1120 (thin-wall) PVC pipe 3/4" PVC "T" 3/4" PVC elbow 3/4" flat-top plug (smooth) 2" long 3/4" PVC stub ("T" to elbow) 6" long 3/4" PVC stub (for mast) 2' of coax (RG-8X, LMR240 or RFC240) with female BNC or UHF connector https://www.ebay.com/itm/133481890997... 28' of 18 gauge stranded hookup wire 4 10" cable ties (2 at center, 2 at ends, 1 at bottom of the noodle) TOOLS: 1/8" drill bit for center hole in PVC pipe 1/2" drill bit for BNC connector threads thru flat cap 7/8" wood bit (spade blade type) for hollowing out inside of cap OPTIONS: 6 Snap-on ferrite beads (Mix 31) for common mode suppression on antenna end of coax https://www.jpmsupply.com/Snap-It-Cor... 3/4-5 TPI tap for threading 1/2" x 3/8" PVC reducer to fit painter poles https://www.ebay.com/itm/254642664421 Telescopic camlock mast (up to 31 feet high) https://docadone.com/products/docapol... Tripod that fits up to 2" diameter mast https://www.ebay.com/itm/363482179344 Guy wire ring, tie-downs, adjusters & ground spikes https://www.ebay.com/itm/114891585326 ASSEMBLY: 1) Mark the pool noodle every 1 inch with a Sharpie 2) Cut pool noodle into 2 sections, each 20" long 3) Drill 1/8" diameter hole at center of PVC pipe thru one side only 4) Slide both noodle sections onto PVC pipe leaving a 1" gap at hole 5) Divide the hookup wire into 2 pieces, each one 14' long 6) Thread both wires into hole and pull both to one end of PVC pipe 7) Strip coax back 1", solder each to coax and cover core and braid each with heat shrink 8) Drill PVC plug to fit coax connector (1/2" thru hole and 7/8" counterbore inside of cap to make thru hole wall about 1/8" thick) 9) Thread coax connector into one end of PVC "T" and out the side port 10) Insert 6" PVC stub to other end of PVC "T" 11) Attach 2" stub to elbow 12) Thread coax connector thru stub/elbow combination and attach to PVC "T" side port 13) Insert connector from inside of PVC plug and secure with its ring nut to flat outside 14) Insert PVC cap with connector onto PVC elbow facing away from noodle 15) Pull wires so that coax pulls all the PVC fittings can be joined together snugly 16) Slide both noodle sections together at hole in pipe 17) Pull wires perpendicular to noodle in opposite directions 18) Bring the up each wire onto the inner end of each noodle 19) Attach cable tie to each at inner ends of noodles to hold wire in place while winding helix 20) Wind one noodle with wire so that helix has even twist with 1" spacing between each turn 21) Wind other noodle with helix in the SAME WINDING DIRECTION as the other noodle 22) Tie off each wire at the outer ends of the noodles with cable ties 23) Adjust cable ties for for wire support at each end of each noodle with snugness 24) Trim off excess tails of cable ties 25) Connect to rig with good quality coax with at least 6 snap-on mix 43 ferrites at BNC-M end 26) Attach to mast at the 6" PVC stub 27) Raise the antenna and test with antenna analyzer 28) Trim both wires to the EXACT SAME # of turns until in resonance at the desired center frequency