If you are looking for a cost effective project that is great for the kids, then consider this maker project that they can use with their handheld HT radios. During our 2016-2017 school year, the supplies for these antennas was only $15.31 per antenna. The largest cost we encountered was for the field line (SMS Extension Cables), and those were $4.61 new, and may be found at local HAM fests. These antennas are great for fox hunts or directional communications.
This antenna build was based off of Joe Leggio WB2HOL's project. It is a beam with a really great front-to-back ratio to use in hidden transmitter hunts. This design exhibits a very clean pattern and is perfect for RDF use. It trades a bit of forward gain in exchange for a very deep notch in the pattern toward the rear. (You could optimize the design for more forward gain, but at the expense of a really good notch in the pattern toward the rear.) It is a design that can be constructed using only simple hand tools (no machine shop needed) and still perform well. It has been duplicated several dozen times by other local hams and has been successfully used as a club construction project.
Building the Antennas
We had 5 kids (and 3 adults) make this antenna during one of our club meetings, and this project took us about an hour and half from start to finish. We even had some kids finish off early and take the antennas out for a spin before they left for the day.
We have put together a detailed instruction sheet a parts and tools list, based off of WB2HOL's project page that is a little more teacher and student friendly. You are welcome to use this document to purchase the materials and walk through the steps with your class. For this project, we did not make a student handout, but you could do that from the document we provide.
You can find the Tape Measure Antenna Project Instructions and Product List here.
There were several things that we did during the build to helped the maker class go along smoothly and we all had fun with it, here is a listing of those suggestions:
- We displayed the following image up on the screen during the build. This was great since the kids kept going up to see the measurements of the different pieces they needed to cut:
- We didn't give the kids all of the parts at once. When you review the document, you will notice that we had multiple steps. We only passed out the parts at the beginning of each step. This allowed us to go around the room and make sure that everyone was on the same page and there were less mistakes being made.
- We designated an adult to do the soldiering. We could of had the kids do it themselves; however, none of them have had a lesson in soldiering yet, and we were pressed on time to get the project done. So, when the kids where ready and had their parts cut and prepped, they visited the soldiering station to have the items soldiered together.
- Another thing we did for fun, was have a BONUS FOR CANDY QUESTION. We got a bag of candy and sat it on the desk, and asked the kids: if anyone can explain why the driven element is (2), 17 3/4" sections and how they came up with those measurements, they win the bag of candy. We left it sitting there the whole build and every once an while asked if anyone had the answer. In the hand out, it says if nobody can answer it to eat the candy in front of them... well, we had nobody who could answer the questions, we didn't eat the candy in front of them though. Going to keep it for another bonus question in the future.
- Another suggestion we used as well. When it came to the tape measures, we (the adults) pulled the tapes all the way out and cut them off. We then laid them on the floor, but the kids actually did the measurements and cut their pieces. This way, we didn't run into an issue with them cutting off the tape measures and letting them curl up into the tape cartridge.
- When we finished our build project, almost every antenna tested out with a 1:1 SWR on 146.565, which was a amazing since it is just constructed from a couple pieces of PVC and a tape measure. The kids were excited that something they created tested out mostly on the first time.