For decades, ham radio has been a great way to send messages from one place to another. For this reason, many antennas have been invented simply out of necessity. Spark transmitters were in use around the time of the great Titanic disaster. Back then they were called wireless, and even to this day, antenna cables continue to send signals towards radio frequencies. Amateur radio has continually progressed and changed since the spark transmitters of that time. High voltage coils were used for their power; they systematically sent the well-known "dits" and "dahs" of Morse code and the person or persons at the other end who could read it wrote down the symbols and formed words. A fantastic and fascinating form of communication, and indeed, it was primitive enough that, looking back today, it can be said that it was a fantastic communication tool.
Step 1. Put emphasis on the antenna
The heart of the ham radio system is the antenna. Many uninformed people claim that potency is the ultimate force. It is not like this! The heart of any radio station, whether amateur, commercial, business, CB, family personal radio or those experimenting with extremely low power (QRP, as it is called) ham radio transmissions IS the antenna. Without good reception, you won't hear much. Without good antennas, you won't transmit very far, even if you apply a high-power RF output or a high-watt output is used.
Step 2. Planning an antenna project can generate many different ideas, but you should always consider the following:
height, length, power cable, balun (and we'll talk about the balun later), insulators, type of cable used, type of metal used, what you want to do with this antenna, how many bands do you want it to transmit, if you can use the correct materials, hanging space, and (biggest of all bans) if you live somewhere that has zoning rules. You may need to ask permission to put an antenna on your property!
Step 3. Use materials that blend easily
The antennas can be made of different materials. Remember to use metal of a similar nature, as dissimilar metals have a tendency to corrode or have non-conductive properties. Metals like copper, aluminum, tin, and steel will conduct electricity, but when we talk about radio frequency or radio frequency currents and voltages, we are talking about "skin effect" electricity. Aluminum antenna cable is difficult to handle, has a very easy breaking point, and is often stretched and deformed and cannot be soldered using conventional soldering. Aluminum cable is inexpensive, but it is the least desired for use in antennas. Copper cable prices have skyrocketed in recent months. Finding old cables from home is the best option. The diameter of a 12-gauge wire is about 0.3 centimeters thick. It is not difficult to handle and is probably the best metal for antennas. Tin wire, used for electric fences, is an excellent antenna wire and is not very expensive. The only downside is that you have to buy it in coils of 0.4 or 0.8 kilometers. If you are planning to build multiple antennas, you will have no problem with this great coil of wire.
Step 4. Learn what works with each stream
Voltages and regular direct or alternating current travel through the center of the cable, while a radio frequency passes through the outer portions of the cable. Imagine a wire with the cut end pointing towards you. If we could see the wire with the current inside it, it would be easy to define. The direct and alternating currents would be those that come out of the center. The radio frequency, however, would be along the outer parts of the cable, as if it were your skin. The type of metal used would have a conductivity scale. Of course, no one will use a precious metal when building an antenna, but rare metals (gold, silver, and platinum) are the three metals that have the highest conductivity. However, as they cost so much, you will have to settle for copper cables, steel with a brass or copper cladding, or perhaps tin, with or without a copper cladding, or a simple tin cable like for an electric fence., or possibly an aluminum cable if you don't have any other cables you can use. Any good conductor of electricity will conduct radio frequencies. The least preferred is mechanical cable, which has high strength and easily corrodes and oxidizes, causing unwanted resistance and antenna failure. When exposed to the weather, the mechanical cable will rust easily, creating an endless problem of either breaks or a HUGE lack of connectivity. This cable does NOT radiate radio frequency energy well and does not receive signals from other amateur radio stations that are transmitting you. One of the best cables, and probably the cheapest, is brass or copper jacketed electric fence cable. Since we are dealing with "skin effect" properties, only the outer jacket of this cable will withstand radio frequency energy. Wire rope should also be avoided, if possible. Steel rusts easily, even if it is clad in brass or copper. The uncoated tin wire used for electric fences can also be used, but make sure you inspect the connections from time to time to remove any corrosion and re-solder them if necessary. Insulated wire made of solid copper can make a great antenna wire. At least seventy (70) percent of all ham radio antennas are made of some type of insulated or uninsulated wire. It is about them that we will talk in this article.
Step 5. Begin by choosing the location and space for the antenna
You should NEVER be near an energized high voltage cable. Many people have been seriously injured or electrocuted by their contact with power lines. Just one touch of these wires can kill whoever is trying to set up an antenna. Locate hanging cables and stay away from them at least a length and a half the height of the tallest pole closest to the cables. The closer you are to the radio room, the safer you will be. Backyard antennas near your radio room make it easy to set up and operate. Try to avoid placing any part of the antenna near where the electricity enters your house. Use a good straight cable and avoid sharp bends or kinks. If you're using tin with copper or brass liners, pay attention to its tendency to roll back on itself. Some tightly wound cables can also be wound on themselves, regardless of the material they are made from or their coatings. Some cables also have a tendency to have sharp ends when cut. Steel is the worst. Good wire cutters can also leave a sharp ridge if used on certain metals. The smaller the cable, the more difficult it is to handle. Using a light gauge wire, be it 17 or 18 through 22 or 24, brings many problems, one of which is durability. The wind can destroy an antenna with 17 to 22 gauge wires in just a few movements. It is recommended to use no less than 18 gauge for most antennas. There are places, as mentioned above, that do not allow antennas, towers or antenna poles to be built. A dipole antenna in the attic of your house is a good idea if you have enough space to place it. Bent dipoles will work great if you don't have a metal roof.
Step 6. Select the cable you want to use
Make sure it is a cable that can withstand the weather, both summer and winter, and is manageable in nature. In other words, don't use a cable that can cause problems later when actually put into use. The copper insulated wire is excellent. DO NOT remove the insulation! In fact, the life of the antenna can be greatly extended if you leave the insulation on the wire. This also insulates the cable from a short circuit against a tree or leaf or even a grass or branch that could fall on it. Make sure that if it's a bare wire, you keep it above the ground (and we'll talk about this later) so that no one comes into contact with it in case it's energized by radio frequency currents. Radiofrequency burns can hurt and deeply burn the flesh of a finger or hand. Radio frequency is a kind of invisible energy and is formed by the forced movements of electrons along a certain path, which is alternating current.
Step 7. Many circuits today can actually cut through multiple layers of skin with just one touch
This burns and often even fries the skin into a white powder. This is called an "RF burn" and its name in English ("RF bite") comes from the fact that it feels as if you have been bitten by some kind of insect, or a bee that has no venom but still hurts deeply. Amplified radio frequency hurts even more because of the extra power applied to the antenna. If you are using a tube type amplifier, depending on the electrical power it is set to, it can cause a serious burn and be very painful.
Step 8. Build your antenna following the proven formulas
Dipole antennas are often the easiest to build and are then converted to inverted V antennas by raising the center of the antenna. It is a good idea for your antenna to be at least half (1/2) the wavelength. One quarter (1/4) of the wave is the minimum height above the ground for effective performance. VHF cable "J" posts are easy to build and can be used in an emergency. These inventions simply use the popular 300 ohm lead wire. You can use them for any frequency, including the high frequency bands, but you will need a tall tower or a large tree to hang them very high. Currently, the 300 ohm antenna cable is quite scarce. A coil of 300 or 450 ohm antenna wire cost $ 55.00 just a year ago. Now if you can find it somewhere, the same coil costs $ 95.00
Step 9. Here you will find other power cables that you can consider using
Choose the cable that suits your particular need. The RG8 mini 8 can handle up to 2 kilowatts. RG8U, which is the large wire with foam insulation or a plastic core, can be used with up to 3 kilowatts. Strong power cables, such as the 9913 series, are best for VHF or UHF transmissions. The 300 ohm covered ladder line is ideal if you have a long extension, such as more than 150 feet. The open power cord causes problems, but you can use it only if it doesn't act as an antenna. If your open ladder line is less than one wave, it can act as your antenna rather than the radiating element of the antenna. Avoid using rare lengths of power cables and try to use cables that use the wavelengths to avoid parasitic transmissions, falling on your neighbor's antenna or interfering with someone's cell phone, or perhaps even sounding nearby home alarm systems in your neighborhood. Unprotected car alarms can often be triggered by using certain frequencies. Take note that if you are running a ham radio station that has been verified, it is NOT your fault if your neighbors are in trouble. Bad design, bad protection and the sensitivity of your equipment are the ones that fail. Sometimes a solution can be reached, other times there is no solution other than putting a filter or suppressor on your equipment to prevent it from failing and acting as receivers. The Federal Communications Commission in the United States, for example, stipulates that your equipment must not cause unwanted interference. To protect yourself, take note of the frequency you were using at the time of the incident and, if your equipment has not been tested, run it through a spectrum analyzer or harmonic detector to prove that your equipment did NOT cause that unwanted interference. If your team is okay, it is up to the other person to do something to prevent their teams from entering the ham radio band.
Step 10. Filter the VHF and MHF bands
There are guys who blame ham radio operators for their own mistakes. There are frequencies that are used that can cause failure of your toys, such as remote-controlled cars, airplanes, or robots. Again, it's not the ham radio's fault. It is mainly due to a flaw in design, protection, or it could be that their toys are functioning as receivers and they blame you for that. That was the case not long ago and we will talk about the outcome of that incident later, but first let's talk about the construction of the antennas.
Step 11. Maximum output
What is the maximum output? The term "average power at the peak of modulation" or PEP for its acronym in English, is the maximum output power allowed by the law from peak to peak, passing in cycles from an alternating current source with radio frequency output. With recent changes in certain laws, the government can also regulate how much power you can use. Legally, ham radio operators can use up to 1500 watts. That's a lot, but consider that a $ 10,000 rig with a 50 cent antenna is not going to serve you very well. Whether you live in the country or in the city, the antenna is the source of good transmission / reception functions.
Step 12. Formula, then manufacture
To find out what length you need for a dipole antenna, which is the most common antenna, use a mathematical equation: 143 / FMHz, where 143 is the standard length and FMHz is the frequency in megahertz, and this gives you the total length of an antenna dipole in meters. Divide it in 2 and place a piece of ceramic, a dog bone or even an insulator made of a PVC pipe between both parts and you already have a dipole antenna. Attach a power cord and go to your tuner or, if you are using resonant antennas, attach your standing wave ratio (SWR) meter and check for high readings. Generally 1: 5 to one or less is acceptable, but a 1: 1 reading is best. Using resonant antennas can be the most rewarding experience of using antennas; however, space and materials may be a factor to consider when using multiple antennas that are resonant to each band.
Step 13. Raising and lowering the antenna can help with SWR, but you should also keep in mind that it is a good idea to raise the antenna to at least 1/4 wavelength above the ground
Inverted V antennas can be tethered as high as possible, but can be positioned as low as 1-1.2 meters above the ground. Post a warning sign where you tie the antenna, if the antenna is low enough that it can be touched, indicating that high voltages may be present at any time and that the wires should not be touched in any way.
Step 14. Stretch the sides of the antenna as far as possible and pull them as high as possible
The larger the available capture area, the better the transmission and reception. Secure the cable with a strong nylon or rayon rope. Use a 1/4 or 1/2 inch plastic one and you will find that these work best, but you should inspect them at least twice a year for fraying or tanning. Replace them if necessary.
Step 15. Build a new design
For many years, designing antennas has been a passion for many radio amateurs. Next on the list is a cage antenna. For this, you will need 10 to 15 centimeter thick PCV wall pipes or a water pipe and a way to cut it into 0.6 to 1.2 centimeter bars. Using a miter saw makes this job easier. Use a 12-inch saw to cut the pipes. BEWARE. The last 12 inches of the pipe may jerk when the saw comes into contact, and the saw may not cut through the pipe and instead throw it at you. Cut only where it is NOT dangerous. Generally there will be 12 to 14 inches of pipe remaining. If you or a friend of yours have this type of saw, use it to cut the pipes. Once they have been cut, measure the outside diameter of the pipe bars in centimeters and millimeters. After you have the circumference, divide it by 6 if you are using 6 cables or by 8 if you plan to use 8 cables for this project. After you have the pattern, use a drill with a 1/8 or 5/32 bit, depending on the gauge of wire used, to poke 6 to 8 holes in each bar. Be as precise as you can.
Step 16. Do not use the same formula for the cage antenna
This will be smaller than a regular antenna. It is relative to the size of the bar you use. You should only use the original formula as a starting point. Depending on the size of the bar, you may have to reduce the length by up to 4%. Just remember that you will use either 6 or 8 cables. Electric fence wire is often a good choice for this type of antenna, as it is relatively inexpensive and can be purchased in large coils of 0.4 or 0.8 kilometer. Tin wire will also work for this project; however, copper is better. Using anything other than copper can compromise the performance of the antenna.
Step 17. Measure carefully, although this is not critical at this time
It is always better if it is too long and then have to add cable, than it is too short. Cuts full extensions for 6 or 8 cables. It is always a good idea to have a couple of friends work with you on this project. Join in the center the cables that you have cut when you have finished the measurements.
Step 18. Assemble your antenna
This is where the fun begins. Slide 5 bars down the cable, using 4 of them, passing them to the other end. Next, space the bars, passing the cables through the holes, at either 18 or 20-inch intervals. Put contact cement on toothpicks or matches before sliding them through the holes with the wires holding them firmly. Leave a bar at the first end; this way, it will show you where to insert your cables into the bars. Continue with the bars, using 4 or 5 at a time, leaving one at the end each time. Tighten the wire and then attach the wires with the toothpicks or matches, using ONLY the wooden part of the matches. After you reach the end of one side of the cage, gather all the loose wires at both ends and tie them together using a piece of wire, wrapping all the wire ends near the center of the bar. Put this side of the antenna aside and do the same with the other.
Step 19. Make it "count."
Whether you use 18 or 20-inch spacing between the bars, to keep it looking good, don't switch the bars to alternating positions. If you're using 18-inch spacing, run the entire length to the end of the antenna. If you're using a 50-centimeter spacing, use it the entire length of the wire. Larger 14- or 12-gauge cables can add weight to this project, so these antennas are quite difficult to get up and running. Do not rush! Take your time, get it right the first time, and then you can be sure that your antenna will serve its purpose. The capture area of a 6-wire cage antenna increases 5 times. An eight-wire antenna increases your capture range by 7 times. Although this ham radio antenna is difficult to handle and build, it is one of the best.
Step 20. Voila
One of the best kept secrets of ham radio antennas is the square loop antenna or the Delta antenna. Resonant antennas cut at the exact frequency in the middle of the band and are used with a tuner large enough to tune multiple bands. The formula used to find a full wave antenna is 306 / FMhz. This gives you the length of a full wave antenna for the band you are using. Placing the antenna horizontally in a triangle shape makes it a Delta antenna. If you place it in a square or rectangle shape, you will have a square loop. This antenna is used most often in the field. It requires a large area of land and can also be connected to either the center or one end of the loop. When climbing this little monster, watch out for power lines. Sufficiently spaced trees provide abundant heights for this antenna. The trees are often called "Towers for the Poor" and can be accessed using various methods, including a good fishing pole and a 110 gram lead correctly pointed at a tall branch of the tree. When this works, tie a mason rope, or you can even attach this rope to the one you are going to use, and gently roll the cane over the branches of the tree and pull it towards the ground. Don't forget to use proper lengths of string for this project. You can use a PCV pipe as an insulator. Cut 3-4 pieces about 15-17 centimeters long from a 3.8 centimeter thick PCV pipe. Drill 1/2 inch holes using a good drill bit and never drill near the end of the pipe. About 2 inches from the end gives you good spacing for the insulators. For the power point, use another piece of PCV tubing, drilling a hole through the center to relieve pressure from the power cord. Apply pressure to the tubing, not the antenna or power cord. Pull the antenna very carefully upwards towards the trees or towards your tower, making sure that it is as close as possible to the design you chose for your antenna (square, rectangular or triangular loop), spacing it as much as possible. You can go a bit wrong on the sides, making one longer than the other, but it's better to keep your antenna as close to the layout as possible.
- Strip the wires carefully, tie the sections that go to ground, and solder to the negative side of your antenna wire. All three cables must be soldered and carefully bonded.
- Use cables of a similar nature. Avoid using cables that corrode easily or can break and lose conductivity.
- Locate your antenna as close to your radio room as possible to avoid loss of radio frequency energy.
- It is fun to perceive the world through a wire. The antennas are the heart of the radio system.
- Using blunt instruments to cut cables can leave sharp edges that can easily pierce the skin. Check each end to prevent these tips from forming.
- Use a PCV pipe for cheap and easy insulators, and also for bars.
- Provides adequate space away from power lines.
- Seek help. It might seem like a fascinating experience to your friends.
- Measure twice, cut once. Although not critical in a cage antenna, it is highly crucial to cut the exact length of an antenna for the band you are going to use.