Section 5.5: Antennas #
Alright, antenna enthusiasts, let’s talk about keeping safe while getting those signals out! Even as Technician class operators, you might find yourself helping with antenna work, so it’s crucial to know the basics.
Antenna installation #
First things first: Look up and live! Before you even think about putting up an antenna, do a skyward scan. Power lines are the arch-nemesis of antenna safety. Here’s a rule of thumb: your antenna should be at least 10 feet away from power lines, plus the full length of the antenna. So if you’re putting up a 20-foot vertical, that’s 30 feet minimum from any power lines. That also means you should avoid attaching your antenna to a utility pole. Better safe than sorry!
Now, let’s talk towers. These are the high-rise apartments of the antenna world, and they demand serious respect. If you’re climbing a tower (which, by the way, should only be done if you’re trained and comfortable with heights), here are some tower truths to live by:
Never climb alone. Always have a buddy on the ground. They’re your spotter, your helper, and potentially your lifesaver.
Proper tie-off is non-negotiable. Use a good climbing harness rated for tower work, and always maintain 100% tie-off. That means you’re connected to the tower at all times, even when moving.
Crank-up towers come with their own set of rules. Never, ever climb one unless it’s fully retracted or the mechanical safety locking device is engaged. These towers aren’t jungle gyms; treat them with respect.
Let’s talk about guy wires for a moment. These are the unsung heroes keeping our towers upright. When installing guy wires, use turnbuckles to tension them properly. Here’s a neat trick: run a safety wire through the turnbuckle to prevent it from loosening due to vibration. It’s like giving your tower a safety belt!
Grounding and Lightning protection #
Grounding is another crucial aspect of antenna safety. It’s not just about lightning protection; proper grounding helps prevent shocks and reduces RF interference in your shack. A good practice is to use separate eight-foot ground rods for each tower leg, all bonded to the tower and to each other. It’s like giving your tower its own personal lightning rod network!
On a related note, let’s talk about lightning arresters - your antenna system’s first line of defense against Mother Nature’s fury. These devices are crucial in protecting your expensive radio equipment from lightning strikes. They aren’t completely proof against a direct hit, but they can still do a lot to protect your expensive equipment.
Where should you install a lightning arrester? The best spot is on a grounded panel where your feedlines enter the building, mounted on a grounded panel. This way, it can shunt any excess voltage to ground before it reaches your gear.
If you have multiple external ground rods or earth connections be sure to bond them all together with heavy wire or conductive strap to make sure everything goes to ground in the same place, rather than running amok through your equipment to find a different path to ground.
When bonding your ground connections, flat copper strap is your best friend. Think of RF like a crowd of people trying to get through a doorway - they can only move along the surface. RF acts the same way (we call this the “skin effect”), which is why flat strap works better than round wire or braid. The wide, flat surface gives the RF current plenty of room to flow, and the shape keeps inductance low. It’s like building a highway instead of a back road for your RF grounding!
Sharp bends in your ground wire (or strap) can increase the impedance of conductor, which can impede lightning when traveling through it. Lightning will take the lowest resistance path to ground, so keep bends in your grounding conductors as gradual as you can to minimize lightning resistance and maximize effectiveness!
If you have any concerns or questions at all, check your local electrical codes; if nothing else, those are the requirements that you are legally obligated to follow!
Be smart #
Remember, the goal is to make contacts and have fun, not to star in the next “What Not to Do” video at your local ham club. Antenna work can be exciting and rewarding, but it needs to be done with a healthy dose of respect and caution.
So, before you start raising that antenna for your first VHF/UHF adventures, take a moment to think safety. Your fellow hams, your radio gear, and most importantly, you, will be better off for it.
Stay safe, keep those antennas high (but not too close to power lines), and happy operating on those VHF and UHF bands!