Wire antennas for SDR Radios: how to make your own.
Hello, my friend and welcome back! This post was supposed to have come out Wednesday, but we had a few technical issues we needed to iron out. Monday, our video was on SDR Radios and how to use them. Today I want to show you how to build a wire antenna for them that will fit in your bugout bag. Now grab a cup of coffee my friend and have a seat while we visit.
What makes SDR so great for bugging out is that you can use them on computers and tablets that have a USB plug. This makes them lightweight and easy to carry. I have mine installed on my tablet and it works great. The only thing is that they need an antenna and to get to some of the HF Frequencies where you can hear people from all around the world talking, you will need a wire antenna if you are on the go.
Wire antennas are easy to build and require little space in a bugout bag when you are on the move. Because they are so long, you will need to be able to throw them over a limb of a tree or even attach them in between two trees or wooden posts. Let me say straight off that I am writing the post with just the bare bones about them so as not to get too complicated. They are so easy to build, you will be surprised.
There are many different configurations of wire antennas that you can use. The simples of these being a vertical dipole antenna. The video shows you how to calculate the length of each leg of the wire based on the frequency or band you are wanting to use. The formula to get the feet needed is 468/ frequency in Megahertz or if you need the inches, you can multiply that by 12. This lets you know how long each leg of the wire you will need.
Some of the different configurations you might want to use are Verticle dipole, horizontal dipole, or inverted “V” just to name a few. As I said, the verticle dipole is the simplest and can be set up quickly. You start by cutting two lengths of wire of the desired length for the frequency you want to use. Next you you will need to connect one end of each to a coax connector. One to the center of the connector and the other to the outside of the connector. Next, you throw one end over the limb of a tree that is high enough to get the wire coming from the center connector off of the ground.
You will then want to stretch the other wire out along the ground. Preferably in the direction of the station you want to listen to. You don’t need to be exact. This antenna can be used to transmit or receive if you have a transceiver, or just to listen to if you are using an SDR radio. NOTE: If you are using it for VHF or UHF frequencies, try to get it high enough to get both wires off of the ground. With these frequencies, the higher you can get it the further you can transmit and receive.
Another simple form of this antenna is the tape measure antenna. This was actually first designed by a dear friend of mine Glenn Thibodeaux in Lousiana. He came up with this and many other antennas of his own design. below is a drawing on how to set one up.
You simply raise the tape until the length shows the wire length you need. The tape measure acts as one side of the antenna and the other is stretched out on the ground and attached to the bottom of the plastic Stake in the ground. You can adjust the antenna by raising and lowering the tape measure.
I’m including several drawings below of other designs you may want to try out. Just remember that radio antennas are basically two wires connected to each side of the coax in its simplest form. I do recommend that you plan on using a #14 wire to make your bugout antennas. WIth one of these antennas and an SDR Radio, you will be able to hear what’s going on while you’re bugging out.
It’s worth noting that you can get a connector for SDR wire antennas that use what is called a “Baulon” to help balance the antenna and connect it to the radio. Here is the one I have. You can also get Baluns for connecting your wire antenna to regular coax as well. See here for an example. I could talk about this all day, but I’m running out of space. If you have any questions, don’t hesitate to add them in the comments below. I answer all of my reader’s questions. Until next time my friend, stay safe, stay strong and stay prepared. God Bless America!