Simple Antenna Demos Antenna Polarization

I’m always amazed when things actually work. So you can imagine my amazement when I actually got the demo shown in the Make: Magazine video below to work.

Diana, KC2UHB, used her lightbulb/antenna combo to demonstrate the principle of directional antennas by using a Yagi as her transmitting antenna. I didn’t have a Yagi handy, so I used one of my home-made J-pole antennas.

Because the J-pole isn’t directional, I obviously couldn’t use it to demonstrate directionality, but it worked quite nicely to demonstrate the principle of polarization. All I had to do was to position the receiving antenna so that it was parallel to the J-pole and the light was nice and bright. Then, I rotated the antenna until it was perpendicular to the J-pole. The light got dimmer and dimmer until eventually you couldn’t see it emitting any light at all. Rotate it back to perpendicular and the bulb burned brightly again.

I think I’ll try to make a video of this down at the Museum this Saturday.

Comments

  1. Mike - WA6ARA says:

    How much power were you using and size (ie voltage) of the bulb?

  2. Dan KB6NU says:

    I was using 10W output, and the bulb I’m using is a GE222, which is nominally a .25A, 2.25V incandescent bulb. The reason I’m using it is that somewhere along the way, I acquired a whole box of them.

  3. This is a great video. I am planning on having my student replicate this later this semester. I would love to see a video of your experiment as well. Thanks for posting power and specs on the bulb. This is just the type of “manageable” hands-on stuff that kids (and adults) need to see. I see wayyyyy too much talk, and not near enough action in showing/demonstrating how things can be built in electronics/radio. I tend to get the “that is so easy, we could do it in no time,” which translates to it will never get done. Keep up the good work at the Museum.

    73,
    Ronny, KC5EES
    Austin, Texas

  4. This is a great video. I am planning on having my student replicate this later this semester. I would love to see a video of your experiment as well. Thanks for posting power and specs on the bulb. This is just the type of “manageable” hands-on stuff that kids (and adults) need to see. I see wayyyyy too much talk, and not near enough action in showing/demonstrating how things can be built in electronics/radio. I tend to get the “that is so easy, we could do it in no time,” which translates to it will never get done. Keep up the good work at the Museum.

    73,
    Ronny, KC5EES
    Austin, Texas

    (I forgot to put in the password characters, now WordPress thinks I’m spamming duplicates..Uggg!)

  5. Mike - WA6ARA says:

    Dan,
    I built it and used it for a demo at the Tech class I am doing last night. Got a lot of WOW!s. Even from the seasoned hams! We built up the beam using the light bulb antenna, and it was very spectacular watching the light dim as we brought the reflector near, or brighten as we brought the director closer. Very informative. This one is definitely in my teaching bag.

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