After reading my last article, you may have gone out and bought a Baofeng for emergency communications. But you realize that you can’t talk to anybody unless they are within a mile or two of you. Most likely that is because you are using the standard antennas, and you live in an area with a lot of trees or large buildings. Your radios use mainly line of sight communications, so anything in between can greatly reduce the effective distance. Perhaps you’ve noticed you can get a little more distance if you are outside on your porch than if you are sitting in your living room. I made a mention of this limitation in my last article. In this next article, we’ll talk about ways to increase your distance.
Upgrade your Antenna
The easiest and least expensive way to increase your distance is to invest in a decent antenna. The short rubber ducky antenna that ships with most handheld radios work, but they are not the best. If you want to stay handheld, you can upgrade to a longer folding antenna. You can keep it folded over for short range comms, or unfold it for longer range capability. Many of these folding antennas will not properly extend if you leave them folded up for too long, so I would recommend leaving it stretched out when in storage if possible, and fold it up when you are packing out.
If you are looking for a mobile antenna, there are many options that have magnetic mounts with extended cables, so you can place it on your roof and wire it into your vehicle, or just pass it through a window if you are against drilling holes in your car. Normally, these antenna cables have pretty large connectors (the PL-259 connector style), but can come with an adapter to SMA (the type on the top of your Baofeng radio) – or you can buy the pigtail adapter separately. This allows you to use your Baofeng with a larger antenna while in your vehicle, and not needing a larger mobile radio wired into the vehicle.
For home-based use, you can get a larger antenna that will mount to the side or roof of your house, or to an antenna tower bolted to a concrete pad outside. This will allow you to maximize the height of your antenna, making it easier to get over the tree line and increasing your line of sight. This also requires a lot more hardware, as you will need a mounting kit and longer cables, plus you will need to drill holes in your walls to get the wire into your house from the exterior mounting point.
And lastly, there are semi-portable antenna stands that will let you mount a large home antenna on a tripod or other base that can be folded up and brought with you to a base camp for disaster operations or other purposes. These are great for if you move a lot, want a setup for when you go camping, or you can use them for a display at events. The first one I saw like this in person was at a CERT training where Smithfield EMA was able to hit repeaters and connect people from Exeter to Providence, about 20 miles as the crow flies. They were using a 5-watt handheld radio to send the transmissions to the repeater
Safety
When considering a home antenna, you will need to look at a few variables for the best results. For any exterior antennas, I always recommend installing an in-line grounding module – and keep at least one more as a spare. These act like surge protectors for your computer and TV equipment, in case of excessive static in the air, or a lightning strike. While this module may blow out during an event, it should protect your radios in the process. The spare module will let you get back up and online immediately, instead of waiting for the replacement unit to arrive. If you are using a steel mast antenna tower, you will want to make sure that the tower is grounded as well. Check for code in your area, but this is usually done by attaching a copper wire from the mast to a steel rod buried in the ground. While you can hook this up to the ground for your house, I would recommend a dedicated grounding system to avoid the possibility of backfeeding electricity into the house.
I am no electrician, but I do have a limited amount of electrical knowledge from my former job. With that basic knowledge as a starting point, I can Google with the best of them. From my research, the National Electric Code (NEC) states that to ground an antenna mast, you need a ground rod (simple rebar works), buried eight (8) feet into the ground, with a little bit above ground (buy a 9- or 10-foot piece of steel). Using a basic grounding clamp designed for the thickness of the rebar, and a second one attached to the mast, connect the mast to the ground rod using at least 10-gauge grounding cable (smaller numbers are larger wire). The best wire to use is stranded, not solid as it is more flexible and easier to make connections. If your mast is painted or coated, you will need to scrape the paint from a section to attach the connector clamp, as you need to attach it to bare metal. In the past, I have found the easiest way to do this is to use fine-grit sandpaper cut into a thinner strip, so you don’t remove too much paint. When you are finished, use an alcohol wipe to remove the dust left from the sandpaper and clean up the area before you install the clamp.
For the portable radio stand, you will want that grounded, but it is impractical to install a 10-foot steel bar every time you move, and nearly impossible to pull it out of the ground without specialized tools. For that, they do make smaller grounding stakes. These might only be 18-24 inches long, but have a wire pre-attached to it, and a loop at the top that you can use to pull it out of the ground when you are ready to take down the setup.
Note that if your exterior antenna mast uses guy wires to secure it, those wires should be grounded as well, as they are attached and can be a source of electrical damage. These can be connected to the same ground rod if they are close, but if you have long guy wires, you may want to install dedicated grounding rods at each anchor point to reduce the length of the groundling wires, thus reducing the resistance to ground. If you have multiple guy wires from each mount point going to different heights on your mast, you can connect them all together with a single grounding wire, as pictured below. Also, if you have guy wires on your mast, you will most likely want – or possible be required by law – to fence off the area encompassing the tower and guy wires. This is mostly for extremely large towers for which, if you are also putting up something over 200 feet above ground level, or the nearest airport, you may also need to look into FAA regulations requiring a flashing light to avoid airplane incidents per Title 14, Chapter I, Subchapter E, Part 77.
Antenna Specs
Now that we know the types of antennas and how they can be mounted, we need to make sure we get the right antenna to do the job. There are several key specifications that you will need to look at and compare, and it is not always true that longer = better or quad band > dual band > single band. If it can’t pick up the frequencies that you are planning to use or can’t handle the higher power of your mobile/base radio, it won’t get you very far. Let’s look at the main factors you will need to review.
Band
Antennas could be single, dual, or quad band – or possibly the rarer tri-band. This means that it can talk and receive on one, two, three, or four frequency ranges, but not necessarily that those frequencies are compatible with your needs. So when you are looking for your upgrade, make sure that you look at the range of frequencies supported. It may say in the product title that it is a “Dual-band VHF 144/UHF 430 MHz”, but the tech specs define that as “136-174MHz / 400-450MHz”. This means that it may work for your 144 MHz Ham frequencies, but it will not work on the 462.xxx or 467.xxx GMRS ranges. For that, you will need a model that can work up to around the 470MHz range. This is probably the single most important specification to look at when comparing antennas.
Max Power Input
This isn’t as critical, but you will want to make sure that the antenna’s maximum power input matches or exceeds the maximum output of your radio. If not, the radio may overheat and burn out, melting the plastic / rubber / PVC covering on the antenna. Depending on where the antenna is located, you can burn yourself or start a house fire.
Gain
Antenna gain does not mean that it increases the volume or signal strength of the radio signals. In directional antennas, a higher gain translates to a narrower beam with a stronger signal in that direction. This can be good if you are trying to hit a specific target, but not if you want wide-area coverage. For omnidirectional antennas, the gain is relatively low – usually under 3 dB, and spreads signals evenly in all directions. This is something that you will want to compare based on your design needs. Longer distance in a narrow beam, or wide area with a reduced range.
Mounting
The mounting connection will depend on your application. If you are building a home or portable base station, you will want an antenna that can mount to your building, your mast, or your tripod mount. For a mobile hookup, the easiest mount type is a magnetic base that you can snap onto the roof of your car and take off when you aren’t using the radio or need to go incognito for a while. And if you are looking for mobile / handheld, then you want something that can screw onto the radio with no wires or adapters.
Connector
The Baofeng radio has an SMA-F (Female) antenna connector. An antenna that attaches to the radio will require an SMA-M (Male) connector. As my cabling product manager once said when I was working at that electronics manufacturer once said, “If you don’t know the difference between male and female connectors, go back to high school biology class”. But to make it crystal clear, a male connector has a pin or connector that slides inside of the female connector. This defines the data line, not the overall layout. In many cases, the male end has the pin, but also a screw threading that actually attaches outside of the female connector that holds the pin. The easiest way to visualize this is with an RG6 (F-Type) connector. Most of you should be familiar with this – it is what is used for coaxial cables that go into your internet router and older TVs.
Exterior antennas typically use a UHF-type connector. However, in my research, you will want to get a little more specific for that, and this is what threw me off for a while. The Male UHF connector is also known as a PL-259 connector. The Female side, however, is an SO-239. Typically, both ends have the same name and/or code number with Male or Female appended to it, but this is one exception that you should be aware of.
Also note that with each additional connection point, your signal is reduced. This means that when you are calculating the cable requirements from the antenna to the radio, you will want to purchase cables long enough for the full run and not connect three or four smaller cables together – with the one exception that you may want two wires if you are attaching an inline grounding device outside just before coming into the house. Adding adapters from one connector type to another will also add to the signal loss, so purchase cables with the proper connectors, or learn to crimp your own to build a custom cable that suits your needs, if you are technical enough to do this.
Physical characteristics
The length of the antenna is the last specification to consider. While this is mainly determined by the frequencies that you will be communicating on and the power input ratings, there is a little bit of play between designs and manufacturers. Really, the only thing you will need to confirm is that this will fit in with the location where you will be mounting the antenna. If you are mounting indoors, for instance, then you may need a slightly shorter antenna that will fit in your attic, especially if it is not a full-standing height area.
Also to consider is the diameter of the antenna and/or the base of the antenna. This is so that you can determine the mounting. Will you need U-bolts to mount to the mast – what size? Do you need a wall-mount arm to mount it? Your antenna choice may determine which mounting brackets will work or not work. Are you looking for a mobile antenna? Not all magnetic mounted antennas are rated for vehicle roof installation and may go flying at high speeds.
Mounting the Antenna
I already kind of covered the types of mounts when we discussed the types of antennas earlier, so I’m not going to waste your time by repeating myself. I’ll keep this very simple. When you are designing your system, remember that antennas work best when installed vertically, not horizontally or at an angle, as these will affect the directionality and distance in certain directions. Also, we discussed that UHF / VHF signals are line-of-sight communications, so we want to get as high above any interference as possible, above the tree line, on top of a tall building, etc. Also, you will not get a great signal indoors – especially if the walls have metal studs instead of all wood construction. Concrete or brick walls will also reduce the signal strength getting outside. For mobile, putting the radio inside the car – a big metal box – will significantly reduce the output capabilities. And lastly, you do not want a high-powered antenna to be placed directly near the radio where you will be sitting while using it, as strong RF radio signals have been proven to cause cancer. This is also why you don’t want to be holding your handheld up to your face like a phone handset – you should hold it out in front of you. So essentially, you are looking for a high, open area away from humans.
Repeaters
Repeaters are used to receive a signal from a low-powered radio and re-broadcast it at a much higher power, and usually from a much better location, such as on the top of a mast at the top of a hill. Repeaters can be a single device, or a system built out with multiple radios and antennas. I would like to give you a rundown of the different types of repeaters, and then I am going to build a duplex repeater from my own Baofeng radios while providing a step-by-step procedure with pictures so that you can repeat this process. Why, you ask? Simple. Because I can. It’s as simple as that.
Now, you can buy a ready-made GMRS repeater on Amazon for under $600 with a lot more power than my handheld radios, but that’s no fun. If you want to really learn how something works, the best way is to build one for yourself. Otherwise, it’s just a magical box that you can spin dials on and make settings changes to, but overall, it’s just there, and it works. Let’s get into this!
Types of Repeaters
There are two main types of repeaters, Simplex and Duplex, and they both have their strengths and weaknesses. Simplex repeaters use a single radio and can use a single frequency – or multiple frequencies if you prefer. But needing only one channel and one radio means there is less hardware to set up and power. The catch is, you cannot transmit and receive at the same time on a single radio, so something must happen. For Simplex, that means you need a controller that can record the signal it receives, then will replay that signal while transmitting on the same radio.
When it comes to Duplex, there is a second radio required in the system, operating on a different frequency. One radio receives your transmission while the second radio almost instantaneously transmits the signal off again. With the design I built, I did notice that the first half of the transmission second is lost while the repeater activates, but the audio was almost perfectly in sync with my voice talking into the radio.
Which is better? Well, that depends on your purpose. Simplex repeating has less hardware and requires less overall power to operate, but has a slower relay, while Duplex repeating has a near-real-time relay, but requires two radios with two antennas, and requires more operating power. But then the hardware for Simplex is complex, requiring a listening, recording, and replaying capability, which means computer controlled. Duplex uses a simple adapter which basically just reverses Tx and Rx lines through the headset/microphone jack connector, so there is less that can fail. I have seen Simplex repeater controllers for as low as $60, and I have seen Duplex repeaters for $20. That difference of $40 is enough to buy a second radio and may even offset the cost of a second high gain antenna, so the costs are close for a small-scale system. Obviously with either design, you can really increase the costs with higher end equipment.
Building a repeater
My Duplex adapter was just delivered from Amazon about 3 hours ago, so naturally I built a Duplex repeater this evening using four Baofeng radios in two different models, tested it, and exported the configurations into Chirp so I can attach it to this article for you to download and use as-is, or modify as you like. Or you can follow the process I will outline below, pick your own frequencies, offsets, tones, and build your entirely custom repeater design. My design is a basic GMRS repeater using approved frequencies. You’re welcome.
In addition to the duplexer, we will need a minimum of four radios. Two will be attached using the duplexer and should have extended antennas. For one of these radios – the Transmitter, or Tx Radio – you will get the most range by using radios on the maximum power, which will vary based on the frequencies you are using, but could be as high as 50 watts, for the GMRS frequencies I am using today. These can be handheld radios, which mine are for today’s test, or they could be mobile or base-style radios. The other two radios will be the radios that will be used by your team to access the repeater to talk to each other. While you can access the repeater with only one radio, you can only get a little static feedback to indicate a successful test. With two user radios, you will be able to receive the signals/voice from one radio to the other and back.
First, we need to understand a few terms and how they relate to what we are doing. Let me create a list for you:
- Base frequency: The frequency your repeater will talk on, and you listen on.
- Offset: The difference between the transmit and receive frequencies. For GMRS or any other 70 Centimeter bands (420-470MHz), the typical offset is + 5MHz. For 2 Meter bands (144-148MHz, the offset is normally + 0.6MHz. On your radio config, this will be two settings. First is direction, plus or minus, determining if the Tx frequency is above or below the Rx frequency. The second is the delta of the frequencies. While this is typically 0.6 or 5MHz, you could set it to anything, including minus 318, to listen on 462.500MHz and talk on 144.500 MHz, from the 70cm band all the way down to the 2M band. There are some security reasons why you may want to do this.
- Private Line (PL) Tone, also known as Continuous Tone-Coded Squelch (CTCS) System: Tones below the audible hearing range (under 300Hz) that are encoded in the transmission to tell the repeater to activate. If configured, the repeater will not activate to re-transmit if this tone is not included in the signal. Radios will have settings for T-CTCS and R-CTCS for Transmit and Receive CTCS tones, which will need to match to allow the radios to talk to each other
- Squelch: Tells the radio how strong a signal must be to accept the input and activate. A higher squelch requires a stronger signal, where a lower squelch will allow more static, noise, or weaker signals to be heard.
- Tx Power: The radio’s transmit power level setting. Available options could be Low and High, or Low, Medium, and High, or possibly actual wattage numbers, depending on your radio. This will determine how much power is sent to the radio and in turn, how far the signal will be broadcast.
Let’s configure our radios with these values. I will give specifics for my Baofeng radios, but the concept can be translated to any radio that supports these values in their configuration. The easiest way for you to configure your radios would be to download my CHIRP file, upload it to your radios, then set them up on the proper channels. In this configuration, channel 0 is the receiver (Rx) radio on the repeater, channel 1 is the transmitter (Tx) radio on the repeater, and channel 2 is for all the user radios that you will be using to talk with your team.
The settings I am going to use are for GMRS Repeater 550/15R, which is a standard repeater, albeit with a CTCS tone that I chose to make sure not just anybody can activate my repeater while I was testing. To make these configurations, use the following menu options – for the radios that I used. If you have other radios, refer to your owner’s manual or scroll through the menu options to determine the proper settings.
Duplex Transmitter Radio Settings
- Base Frequency: 462.550
- Offset: Not configured
- CTCS Tone: Not configured
- Squelch: Not configured
- Tx Power: High
- Radio volume: Low (saves battery as we will not be listening on this radio)
Duplex Receiver Radio Settings
- Base Frequency: 467.550
- Offset: Not configured
- R-CTCS Tone: Cross Tone mode, Tone Squelch 77.0 MHz
- Squelch: 3
- Tx Power: Low (This radio is not transmitting)
- Radio volume: High (The louder this audio comes in, the better the signal that will be re-transmitted.
User Radio Settings
- Base Frequency: 462.550
- Offset: + 5 MHz
- T-CTCS Tone: Tone Mode, 77.0 MHz
- Squelch: 5
- Tx Power: This will be based on your needs, and how far you are from your repeater. I set it to low for testing, but you may need high to reach it if you are moving far from the repeater.
- Radio volume: Based on your needs in the field
You will need at least two radios configured with the same settings so you can talk to each other, or this does no good. Also, you will note that in the first picture below, you see the frequency of 462.550, but in the second, while I am pushing the talk button, the frequency changes to 467.550. This tells you that the offset settings are properly configured.
Great. Now you can configure the radios yourself. You want an easier way? Here is my CHIRP file. You will need to download the CHIRP app from their website for free. They support Windows 10 and later, Mac OS 11 “Big Sur” and later, and “All modern distros” of Linux, per their site. The last component will be the USB cable that comes with most radios, or purchase one online or from a local store that sells radios and radio accessories. This takes a little practice, but you basically connect the cable to the radio and to your computer, then turn the radio on and make sure it’s on a channel that isn’t hearing any traffic, as this can interfere with the read/write. I disconnect my antenna to further reduce chances of interference. Select Radio, then Download from Radio (I know, we want to upload, but trust me here). The software should identify the correct port to use. Choose your radio’s make and model from the list, and click OK. This will pull down the current program on the radio (if it’s new, there will be a long table of nothing).
Next, click File, then Open. Browse for the file I provided that you downloaded above. This will open up and show three lines – RXRADIO, TXRADIO, and USER. If you have no configured programs on your radios, you can just click Radio, and Upload to Radio and you will have all three channels, then you can select which radios use which channels. This will delete anything you have programmed on your radio prior to uploading however. If you don’t want to overwrite this, you can highlight the line (or lines) you want to move over, click Edit, then Copy. Once copied, click the tab at the top for your existing program, find an open channel space, and paste the repeater configs to this program file. If you want to edit my code to use different frequencies, do it here – just make sure the numbers you choose line up so it will work (Tone and Tone Squelch match, Off-D and Offset math out to the new Tx and Rx Base Frequencies, etc.)
Now we have all our radios configured, and your duplexer has arrived in the mail. Let’s assemble the repeater now. This is the easy part for a basic setup, but you can make it really complicated if you want to. For a test, let’s just set up a very small system. To do this, pop open the speaker/microphone cover on the right side of the radio. Connect the Rx radio to the cable attached to the “Receiver” side of the duplexer, and the Tx radio to the cable attached to the “Transmission” side of the duplexer. All done, it really is that easy.
If you want to get fancy, you can pick up an ammo can or a hard plastic waterproof case with foam and cut out holes to fit the radios and the duplexer module, so they aren’t bouncing around and changing channels or reducing the volume. Drill a couple holes in the side that you can pass cables through to attach to a larger external antenna – just use a rubber grommet that will stop water from getting into the case. You can also include a USB battery pack if your radios have USB charging ports on your radios to extend the battery life. You could even drill a third hole for a power line that will attach to a solar panel so you can charge your battery bank during the day, allowing it to power the radios all night, and you will have a fully self-sufficient repeater with no need for any contact to keep it running, unless there is a system failure. Determine how you want your repeater to be built, and with which accessories, to ensure that the case you purchase will be big enough to house all the components you desire.
The final consideration is placement. This should mirror my comments way up near the top in the antenna discussion. The higher the repeater’s antennas, the better distance you will have in reaching it, and the better distance it will have in transmitting your signals. If you build your repeater into a waterproof box, you can mount the antennas and solar panels directly to your case, and place it on top of a roof, or secure it near the top of a tall tree and walk away. If you want to use this as a mobile platform, you can pack it up and attach the antennas to your vehicle, allowing teams to communicate within several miles of your current location, and move with them. Or you can set it up as a base and mount the two antennas on a tall mast at your home and run wires to the radios in your home.
