Turning a Can of Ham Into a Ham Radio Antenna
See how amateur radio enthusiast Ben Eadie constructed a working ham radio antenna from little more than an empty can and copper tape.
Ham radio antennas
Since the early 20th century, people around the world have been sending and receiving amateur radio signals to learn and communicate with each other. But before any of this can happen, operators must obtain the requisite licensing, transceivers, and most importantly, the antenna for broadcasting/picking up radio waves.
Ham radio can rely on a wide variety of antenna configurations, as certain structures convey specific benefits and/or cost savings. Slot antennas in particular are quite simple as they are, at least topologically, a conductive plate with a slot cut in the middle. With this in mind, the Ham Radio Rookie (Ben Eadie), started a series called "Will It Ham" in which he experiments with various commonly available items to see if they will make suitable antennas. And in his inaugural video, he built a ham radio antenna from an actual can of ham.
Finding the ideal conductor length
Due to how radio waves interact with conductors, one has to be mindful when building their antenna of what frequencies of signals it will pick up and radiate the best. Since the 70cm/440MHz band is popular and has readily available equipment, finding a can with a 35cm circumference would be ideal since it is half the wavelength's length and can let the signal resonate well within the dipole slot antenna. Luckily for Eadie, his can of ham measured in at exactly 35cm around.
Building a mount and slot antenna
After cleaning out the residual ham from the can and splitting it in half, Ben designed a series of 3D printed spacers that fit between the two halves and keep them around a quarter-inch apart. Next, he sanded away the can's ink in order to attach a piece of copper tape across the two halves to complete the slot antenna along with two other places for the signal feed points. Finally, he glued the ham can to a piece of PVC and prepared it for a test.
Does it work?
Once outside and near a 70cm repeater, Eadie reached out to his friend to get a read on if the can works in the first place and to hear how noisy it is. Much to his surprise and delight, the results were great as others could hear him clearly and vice-versa. With this success, Eadie plans on expanding his range of experiments to other, weirder items and even try putting the ham back into the can for the ultimate "ham ham can antenna". You can watch this project's build log and subsequent test here on YouTube.