Antenna Launcher Guide: Getting a Wire Antenna Into a Tree

Almost every wire antenna has the same first problem: before you can tune it, measure it or work a single station with it, you have to get the end of a line over a branch that is twenty metres above your head. A good antenna launcher turns this from an afternoon of frustration into a ten minute job. This guide explains the common ways of getting a line over a tree, which line and weight to choose, how to turn a thin shooting line into a strong support rope, and which safety rules matter. It is written for the wire antenna builder who wants a reliable, repeatable method rather than a lucky throw.

Why Getting a Line Into a Tree Is Hard

A tree is the cheapest and most flexible antenna support there is. Dipoles, inverted V antennas, slopers, end-fed wires and vertical wires all benefit from a high, clear support point, and the higher the support, the better the antenna can perform on the lower bands. The difficulty is that the best branch is usually high, thin and surrounded by smaller branches, and a heavy rope cannot be thrown that far. The solution is to start with something light that can be launched accurately, and to use it to pull up progressively stronger lines until the antenna wire or its support rope is in place.

There are four common ways of doing the first step, and each has its place: throwing a weighted line by hand, using a throw bag, shooting a weight with a slingshot or a purpose-made launcher, and using a pole to lift the line. We will look at each, but first it helps to understand the principle that all of them share.

The Two-Line Method

The method that most experienced antenna builders use has three stages. First you launch a light shooting line over the target branch with a weight. Second, you attach a stronger line, often called a pull line or messenger, to the end of the shooting line and pull it over the branch. Third, you use the pull line to pull up the real support rope or, if the antenna is light, the antenna itself. The system works because each step carries a heavier load than the last, and because the weight does the difficult job only once.

Plan the rope arrangement before you leave the ground. In most cases it is best to pass the rope over the branch and then to tie both ends to something at ground level, so that the antenna can be raised and lowered without climbing. This is called a halyard, a word borrowed from sailing. A pulley at the top is a luxury that makes hauling much easier and reduces rope wear, but it is not essential for light antennas. Our guide to push-up masts and guying covers the other common approach, and many stations use a tree at one end and a mast at the other.

Choosing a Shooting Line

The shooting line has to fly freely, survive friction in the branches and be strong enough to pull up the next line. Fishing line is the usual choice, and the fishing line article explains the main attributes: material, thickness, breaking strength, knot strength, abrasion resistance, stretch, memory and visibility. Most modern lines are made of synthetic polymers such as nylon, polyethylene or fluorocarbon, and they come as monofilament or braided multifilament. Both types have been used by antenna builders, and each has strengths.

• Monofilament is smooth and often tangle-resistant when it comes off a spinning reel, and it is easy to find. It has more stretch and more memory, which means that it can coil and kink if it is stored badly.
• Braided line is thin for its strength, has little stretch and can be easier to feel in your fingers. It can cut into skin under load and may cut through a softer line if used carelessly, so wear gloves when you pull on it.
• Bright colours help you see the line in the air and against a dark tree, which saves time when you must find the end in the grass.

Whichever you choose, check the marked breaking strength and compare it with the load you plan to pull. As a general rule, the shooting line only needs to pull up the next, heavier line, so you do not need a very strong one. A line that is too thick, on the other hand, adds weight and drag and makes the launch shorter. Use a reel, a fishing rod reel or a simple spool that lets the line pay out freely without tangling. A reel with a push-button or open-face release is popular because the line can leave the spool with almost no resistance.

Choosing a Weight

The weight must be heavy enough to carry the line over the branch and to drag it down on the other side, yet small enough to launch easily and not to cause harm if it falls. A small bag of sand or shot, a purpose-made throw weight, or a soft bag with a rounded shape are common choices. Avoid hard, sharp or metal objects when possible, since they can damage the branch, the line or your property if the shot goes wrong. A smooth, rounded shape slides through the leaves and branches more easily than a flat one. Many builders use a weight with a hole for the line so that it can slide down after it has crossed the branch.

It is wise to test the weight and line in an open space before you try it near the tree, so you can judge the range and the accuracy. Practice with a marker on the ground and aim at a branch that you can see. Once you know how the combination behaves, you will waste fewer shots, and fewer shots means less tangling and less wear on the line.

Slingshots and Dedicated Launchers

A slingshot is a small hand-powered launcher. In its classic form, according to the slingshot article, it consists of a Y-shaped frame, two strips of rubber or synthetic elastic attached to the upper ends, and a pouch that holds the projectile. One hand holds the frame while the other pulls back the pouch. Antenna builders have used this simple principle for many years to launch a weight with a line attached, and there are commercial products sold as antenna launchers that are designed for that task, with a reel mount and a safer weight.

The advantage of a slingshot launcher is height and accuracy. A good shot can reach a branch that is far beyond the reach of a hand throw, and a launcher with a sighting aid allows you to repeat a shot that nearly worked. The disadvantages are cost, the need for space around you and the greater potential for harm if you are careless. Because the same device can be misused, treat it with respect, follow the manufacturer’s instructions and check local rules on their use. Never aim at people, animals, vehicles, windows or power lines, and never launch toward a direction where you cannot see where the weight will land. Wear eye protection, and make sure that bystanders are well out of the way.

Throw Bags and Hand Throws

If the branch is lower than about the height of a house, a hand throw can be the quickest method. A throw bag is a rope stuffed loosely into a bag so that it pays out through the top when the bag is thrown. The idea comes from water rescue, where, as the throw bag article explains, it is standard equipment for kayaking and other river activities. Tree workers and antenna builders use weighted bags of similar design to throw a line over a branch. The bag trails a line behind it, and the flight is easy to judge because the weight is compact and the line stays untangled.

Throwing technique matters. Hold the end of the line firmly, since a throw that ends with the line leaving your hand wastes the shot. Use an underhand or overhand throw, lead the target and aim for a point well above the branch, because the weight will arc down and the line will pull it back as it drops. Stand clear of the area where the weight will fall and keep an eye on other people. Many people find a soft bag more comfortable than a hard weight, and it is less likely to cause damage when it lands.

Using a Pole or Extension Mast

When a launcher is not allowed or not practical, a lightweight pole can lift the line high enough to hook it over a branch. Telescopic fibreglass poles, which are also used as antenna masts, can reach several metres. A small pulley or a hook at the top of the pole holds the line, and you walk the pole beneath the branch and pass the line over. It is slow and quiet, and it does not require a launch. It is also useful for adjusting a line that has caught on a twig or for guiding a rope into position. If you already have a pole for a wire antenna, as in our article on the inverted V antenna, you can use the same pole for this job.

Comparing the Methods

Step-by-Step: A Typical Installation

1. Choose the branch. Pick a strong, healthy branch with a clear path to the ground on both sides. Avoid dead wood and branches that hang over buildings, roads or power lines. If possible, choose a branch that is far enough from the trunk to give the antenna wire room to hang.
2. Plan the antenna. Decide how long the antenna wire is and where the other end will be tied. Our guide to the sloper antenna shows how a single high support point can serve a whole antenna.
3. Prepare the line. Fit the reel, tie the weight with a secure knot and lay out the line so it can pay out freely. Test the knot with a firm pull.
4. Launch. Aim above the branch, not at it. If you miss, retrieve the weight, check the line for twists and try again. Do not keep shooting if the line is tangled.
5. Replace the weight with a pull line. When the weight reaches the ground, detach it and tie the pull line to the shooting line with a secure knot. Pull the shooting line back over the branch until the pull line is over.
6. Pull up the support rope. Attach the rope that will carry the antenna to the pull line and pull it over. Use a rope that resists sunlight and moisture, because it will hang outside for months or years.
7. Raise the antenna. Tie the antenna to the halyard with a strain-relief arrangement, so that the load does not pull on the feed point or the wire. Raise it and secure the rope at ground level.

Antenna Wire, Movement and Wear

A tree moves in the wind, and a fixed antenna wire will eventually break at the point of highest tension. Use a system that lets the wire move, for example a weight or a spring at the end, or a halyard that runs over a pulley and holds a weight at the bottom. This arrangement allows the antenna to rise and fall slightly without breaking. Check where the rope crosses the branch for abrasion, and add a short sleeve or a pulley if the rope is rubbing. A seasonal inspection should include the ropes, the knots and the wire, just as for any other antenna. Weatherproofing the coax at the feed point also matters, and our guide to weatherproof coax connectors explains how to protect it.

Safety First

Launching a line into a tree is a simple job, but safety comes first. Keep every part of your antenna and every line well away from overhead power lines, since a wet line or a wire can conduct electricity. If the best tree is near a power line, choose another tree. Do not climb a tree to place the line unless you are trained and equipped, and never climb during a storm. Check whether your property or local rules allow what you plan to do, and ask the owner of the tree before you attach anything to it. Protect the tree by avoiding wire wrapped around a branch, which can cut into the bark as the tree grows.

Also think about the people around you. Make sure no one is within the launch area. Keep children and pets away. Use eye protection. Do not use a launcher in a crowded area, and never in a direction in which you cannot see where the weight will land. If a weight gets stuck in a branch, do not pull hard on the line, because it may snap back. Cut the line and leave it, or retrieve it using a pole when it is safe to do so. For more on safety at height, see our guide to ham radio tower safety.

Common Mistakes

• Using a line that is too heavy. A heavy line reduces the range and accuracy. Use the lightest line that can do the job.
• Aiming at the branch instead of above it. The weight falls as it travels, and the line adds drag. Aim above the target.
• Using weak knots. A weak knot often fails when the line is under load. Test it before you launch.
• Forgetting to plan the return path. If you cannot lower the antenna, you cannot maintain it. Always include a halyard.

The Bottom Line

An antenna launcher, a throw bag or a simple pole are all ways of doing the same job: getting a light line over a high branch so that you can pull up stronger ones. Choose a light, bright shooting line, a smooth weight and a plan with two lines and a halyard, practise before you aim, and keep everything clear of power lines and people. With a little practice, a tree becomes a tall, free and flexible antenna support, and a wire that was once difficult to place becomes a part of your station that you can raise, lower and maintain with ease.

Frequently Asked Questions

What is an antenna launcher?

An antenna launcher is a device, usually a slingshot-style or spring-powered tool, that shoots a weight with a thin line attached over a high branch or support. The thin line is then used to pull up a stronger rope or the antenna itself.

Which line is best for launching over a tree?

Fishing line is the usual choice. Monofilament is smooth and easy to handle, while braided line is thin and strong with little stretch. Choose a bright colour so that you can see it, and use the lightest line that can pull your next, stronger line.

How do I get a heavy rope over a branch?

Use the two-line method. Launch a light shooting line first, tie a pull line to it and pull it over the branch, and then use the pull line to pull up the heavy rope. Each step carries a heavier load than the last.

Is it safe to use a slingshot for this?

It can be, if you follow the safety rules. Use a soft or rounded weight, wear eye protection, keep people and animals out of the area and never aim at power lines, windows or vehicles. Check local rules and the manufacturer’s instructions.

What if the weight gets stuck in the tree?

Do not pull hard, because the line may snap back. Try to free it gently from a different direction, use a pole if it is safe, or cut the line and leave the weight rather than risk an accident.

How high should I place a wire antenna in a tree?

As high as safely possible. Height helps the antenna on the lower bands, but it must be balanced with safety and with the strength of the branch. Choose a strong branch, keep clear of power lines and check the setup after storms.