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Antenna Projects

Measuring Tape Yagis

One of the joys of ham radio is being able to construct antennas from every day stuff. There are few projects more fun and interesting than building  a tape measure yagi antenna.

Yagi antennas consists of a "driven" element with a longer "reflector" element behind it that signals bounce off of and shorter "director" elements in front to draw the signal in that direction. They can be pricey to buy in the store, but you can make an interesting working Yagi that can be folded up and stored in your car. Tape measure Yagis are built from an old tape measure, pvc plumbing pipe, and some hose clamps.  You can use it with your handheld to focus your signals in one direction, but where they really shine are hidden transmitter fox hunts and you are constantly jumping in and out of vehicles with your antenna.

Download the plans, buy some plumbing PVC, a cheap one inch tape measure, six hose clamps, scrounge six inches of wire and some hardware, and come to project night and we'll help guide you into building your own directional antenna. Test it out right there on a fox hunt transmitter. You'll be thrilled when you follow the signal to the fox.

J-Poles

A J-Pole antenna is another great project antenna. Another antenna you can make from parts from the hardware store. You'll need a 10 foot piece of copper plumbing pipe a couple of fittings and a little soldering know how. It's a half wave antenna that is fed from the bottom. Mount it outside away from the house and be pleasantly surprised how far you can talk on your HT.

Bring your parts to project night and we'll help you solder all the parts together. Gideon Kohler KJ6ZBJ is our resident J-pole expert and is always happy to help you out. If you want to make a J-Pole, give us some advance notice so we can make sure that Gideon can be there.


Super J-Poles

The Super J is an interesting twist on the above j-pole design. It's also called a co-linear. In a Super J antenna, a second vertical antenna segment is mounted one on top of the other with an insulator between them. Now picture a graph of a wave passing along an antenna. When the wave goes up the voltage is positive, when it drops down the voltage is negative. If the two antennas were connected one would be positive phased and at the same time the other is negative. The antennas are resonating out of phase.

In a Super J, a third antenna segment, bent into a U shape is added between the two radiating elements. It's called a phasing loop and basically causes both antennas to radiate at the same time or in phase. The net result is the pattern of radiation that would normally be doughnut shaped now is squashed flat into a thinner pancake pattern. Some of the energy that would have been radiated up into the sky and into the ground is now radiated out flat. The good side is it boosts your effective power to any station that is within that field. The bad side is the field can be so thin and narrow, you can miss stations that are over or under the field.

Just like the J-Pole, most all of the parts can be bought at a hardware store.


Dipoles

Dipole antennas are probably the simplest antennas to construct. The antenna looks just like the name implies- Di pole or two poles. In its simplest form it's two equal lengths of wire. One length connects to the center conductor of your coax. The other length connects to the braid of your coax. Plain and simple, if the wires are cut to the right length then that will get you on the air.

Dipoles can be used for any bands but are typically used by the home antenna builder on HF bands where the length of the antenna dictates something simple to construct.

To make a dipole, select the center frequency you would like to operate on and cut a wire that is a 1/2 wavelength of that frequency. The easy formula is to take the frequency and divide that number by 468 to get the length of a half wave for that frequency. Cut that in half and attach one piece to the center conductor and the other to the braid of your coax. There will be factors in your antenna placement that you cannot control and will affect the actual length needed for the wires. Things like height off the ground or the location of nearby objects will slightly change the characteristics of your dipole causing it to be longer or shorter than what you calculate. After erecting, test your antenna with either an antenna tester or SWR meter and then adjust for lowest SWR It's best to make the antenna long and cut off pieces as needed.

While the above setup will likely work, however, you stand the chance of the radiated wave flowing back onto the outer braid of the coax instead of the leg of the dipole. This will work and people will hear you, but it does present possible problems like radiating inside your ham shack area or picking up noise from electrical objects like computers or TVs in your house .

To get around this you should purchase a balen. Your coax attaches to the bottom of the balen and the two ends of the dipole attach to the top. This device effectively isolates your feedline from the antenna and gives you a cleaner signal.



Tiger Tails

A simple, inexpensive and effective expedient to improve a "rubber duck" antenna is a counterpoise or "tiger tail". Make this from a piece (19.5" on 2m, 11.5" for 220 and 6.5" for 440) of stranded wire, crimped and soldered to a battery clip. Your antenna acts like a center-fed dipole instead of an end-fed dummy load and adds up to 3db to your TX/RX signal. In marginal conditions extend it horizontally, pointing your hand to direct the main lobe of the radiation pattern in the direction where you need a stronger signal.
Download Plans

Upcoming...

  • January 23, 2014 The next project night will be devoted to helping Lynne (KK6FHV), Ken (KK6FHU) and the Red Cross team clean up the back room for the Red Cross open house in February.
    Red Cross Bldg., Crescent City 7:00pm

  • January - February 2014 (tbd)Antenna Party at Fred Wagner's (AD6FC) house. If you'd like to participate, talk with Mike Poole (KE6ZYK).

  • February 15, 2014This will be a "learn your radio" session and our goal is to let new amateurs talk across the room to each other so they don't feel so intimidated trying to talk on the nets for their first contacts. Mike, Fred, Doug, Mindy, Paul and others have all volunteered to help mentor the new hams. This is also open to all amateurs, so if you know of someone who has their license but needs a little help, tell them they are welcome.
    Red Cross Bldg., Crescent City
    9am-12pm

  • March 2014 Tiger Tails
    Learn More>>


Antenna Romance

Two antennas met on a roof, fell in love and got married. The ceremony wasn't much, but the reception was excellent. Since they were a perfect match, soon they generated harmonics. Wrapped the harmonics in dipoles. But later the harmonics turned out to be parasitic elements. The true story -- she was a tri-bander and he felt trapped, so they went on separate beam headings

Contact Us

Del Norte Amateur Radio Club - W6HY
1672 Northcrest Dr.
Crescent City, CA 95531
United States
Club: w6hy@w6hy.org
Web Master: webmaster@w6hy.org
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