American Partisan: HF NVIS Antenna

NC Scout of American Partisan talks about the HF NVIS Antenna.  Also check out a follow up post here.

In the last Radio Contra I discussed a simple way of rigging up an antenna for NVIS HF use. Its a topic that gets a lot of attention, and in turn, a lot of confusion. But trust me, its simple. The whole point behind HF is creating regional communications- anything that’s beyond line of sight– and while you can spend a heck of a lot of money in a hurry and not get a lot, you can spend just a few bucks and with a little knowhow I’m about to impart here, have a great setup.

NVIS relies on sending as much of your radiated energy skyward as possible, with as close to a zero degree takeoff as possible. So, this means a horizontal antenna close to the ground. In case you’re wondering, the takeoff angle is perpendicular to the orientation of the antenna- so, if the antenna is vertical, you’ll have a very shallow takeoff angle, aka groundwave, if its horizontal, the radiation goes vertical. NVIS generally works best between 1.8-8mHz, with the higher frequencies working better during the day and the lower ones at night.

I’ll also add to this that the direction finding threat almost exclusively comes from groundwave. So on HF, NVIS is what you’re looking for. As little groundwave as possible.

So with that said, let’s talk about this antenna.

The first thing to know is that its built out of dirt cheap materials. 128ft 14AWG stranded wire, a Cobra Head, and ten plastic electric fence posts. Less than $25 or so.

For an 80M dipole antenna, each leg is going to be roughly 64ft long. You can make a loop or use a ring terminal to secure the wire to each end of the cobra head. Stretch it out- now you’ve got a dipole. Those plastic fence posts serve both as a suspension for the antenna and as an insulator. All you have to do is wrap the ends in a loop, and boom, you’re ready to rock and roll.

The antenna itself is roughly 2ft off the ground. This creates a high amount of reflectivity from the ground, sending your radiation almost completely vertical.

And with that, you’ve got a dirt cheap antenna that works pretty well. If you want to see how it works and get hands on building one, come out to class.

Brushbeater: Antenna Polarization and COMSEC

NC Scout at Brushbeater has an article on Antenna Polarization and COMSEC (communications security).

So you’re out there on a patrol, the commo window is open and you need to make a Cyril Report back to your TOC. Your RTO sets up the yagi getting ready to make contact, checking and rechecking the azimuth. He glosses back over the transmit and receive frequencies to make sure everything is set, double checking the report to make sure nothing was missed, and getting the approval from you, the Team Leader. You notice one small thing- the Yagi is horizontal, not vertical, and a slow grin grows on your face.

You’ve got a good man on the Team who paid attention.

There’s one element to small unit communications that usually gets zero attention- antenna polarization. Let’s take a look at our most common denominator at the basic level- the Baofeng UV-5R. Its a VHF and UHF FM two-way radio. FM nearly always uses vertical polarization, meaning in simple terms, the antenna is straight up and down.

In a conventional environment we do this for two reasons. First, pretty much everyone else is vertically polarized when communicating via FM, and second, there’s 9db of loss between a vertical polarization and horizontal polarization. Wait, what?

Like how we measure light in Lumens, signal strength radiating from an antenna is measured in decibels (db) of gain or loss. With each 3db of gain, we double our effective radiated power (ERP) in terms of signal strength. With each 3db of loss, we cut our strength in half. This is measured in orders of magnitude, meaning that with each 3db, the strength doubles on itself (4w x 2= 8w x 2= 16w, etc). Taking that into account, the difference in strength between horizontal and vertical polarization is 9db- quite a difference. If someone is using a vertically polarized antenna to attempt to intercept my transmission, they’d likely be using vertical polarization. After all, why wouldn’t you? Nearly all FM transmissions are vertically polarized, its common practice. But if I change my operating practice to account for this, now they’re going to have a harder time both intercepting and getting a bearing on me.

Not impossible, mind you. But much harder. And that’s on top of my other operating practices, such as transmitting on one frequency and receiving on another, keeping my transmissions as short as possible, and making sure I’m always using directional antennas. It goes without saying that your intended receiving station should be matched in polarization. Its a basic practice that, when coupled with my other techniques, turns inexpensive equipment into much more formidable gear for clandestine or unconventional forces operating in the field.

Brushbeater: The Jungle Antenna Revisited

NC Scout at Brushbeater has a new article worth your time if you are into radio communications – The Jungle Antenna Revisited: Task and Purpose for the Partisan and Prepper

Going back to the early days of the Brushbeater blog, the Jungle Antenna post has been and continues to be one of the more popular posts I’ve done. And for good reason- I wrote it to be used. It’s the antenna every student in the RTO course builds and one of the designs they get hands on with, and it’s the one that they know works from the demonstrations we do with them. But often, as with everything, a context for the task and purpose has to be clarified.

Students in the RTO Course preparing an improvised Jungle Antenna for use.

Many preppers who contact me fall into a similar trap. I have an goal and recognize a need. What can I buy that does for me what I want it to do? How do I do this in the most cost-effective way? And finally (but what should be first), how do I obtain the skill to best use the gear I’ve purchased? Its a problematic point of view for a lot of reasons but one I get frequent questions about nonetheless. And that’s ok. I’ll normally answer it the same way- Use your stuff, Learn to use it even better, and never stop!

One of my objectives back then, as it remains in my classes and writing today, was emphasizing the skill of building your own equipment. With communications that’s improvised antennas, because it’s one of the better skills to have. Taking common and cheap components and using them to boost your capabilities is a great talent to have and makes you a force multiplier for your team or group. Those skills have served me very well and for the great people I’ve had in class, it’s went on to help them too. The end goal is getting the most bang-for-buck out of a piece of equipment as possible and with radios, that always means focusing on antennas.

The Jungle Antenna, 292 Antenna, Groundplane, OE-254 or whatever else you wanna call it, are vertical antennas designed to boost range from the relatively inefficient antenna on your radio while using the same power. It does this through efficiency; an antenna has to match, both the ‘hot’ element and the ‘cold’ element (positive and negative, respectively), in order to be resonant. Resonance is another term for an antenna’s electrical match to a particular frequency. And that resonance is measured through wavelengths– with each leg of the Jungle Antenna being one quarter wavelength long. It’s an incredibly simple antenna but it’s one that improves your transmitting and receiving ability- something you definitely want.

Jungle Jim operators in Vietnam getting a commo check before a patrol. Likely packed away in that ruck is a rolled up Jungle Antenna, ready to get strung up.

The Jungle Antenna gets its name from an interesting time in American military history. During the interwar period of the 1920s-30, the Army Signal Corps was experimenting with antenna designs to boost the range of their SCR (Signal Corps Radio, pre-A/N PRC designation in case you’re wondering) in jungle environments. Testing the designs in Panama, they found that if you take a vertical dipole and add two more negative elements, it boosts the radio’s signal in all directions even when the thick vegetation would otherwise absorb the signal. It found its way into use with groups fighting in the island campaigns and in Burma. Even though the crude radios would eventually fail from the humidity and harsh conditions, the antennas worked. Imperial Japan was also experimenting, with two engineers named Yagi and Uda coming up with a directional antenna that still bears their name. Both became very popular designs, with the Jungle Antenna saw extensive use in Vietnam and is still being taught to unconventional warfare RTOs today- because it’s simple, rugged and it works. This history provides us with a bit of context for the antenna and its intended use. It’s an omnidirectional antenna, creating a stronger signal in all directions, optimized for heavy woodland and jungle environments where much of your signal might be lost.

The Jungle Antenna up and running. We’re standing right under it and it disappears- think about how it’ll vanish in just a few more steps.

Why you want an Omnidirectional Antenna?

The Jungle Antenna does two things really, really well. It takes even a small amount of power and squeezes more range out of it, by getting your actual antenna higher, meaning more line of sight, while doing it much more efficiently. It also allows your radio to listen to other traffic much better. Because of it transmits and receives in all directions, this is a great antenna to have up for networking now– and when put up in the trees, the thin wire and natural materials make it virtually disappear. So even if all you’ve got is that $25 Baofeng, you can still get an impressive range out of that 4 watts that the UV-5R puts out. Not too shabby for something you can build out of a split post BNC adapter (the real name for what us Army guys call a Cobra Head), lamp cord and electric fence insulators.

Another, more tactical reason to have an omnidirectional antenna is in a retreat setting where a tactical operations center may have to communicate with multiple patrols simultaneously, and an omnidirectional antenna would increase the range of the radio at the base. I strongly suggest radio operators on a team carry one for their Contingency frequency also. People get lost, routes become compromised, plans change. When those plans change, it’s likely that a team in trouble needs their radio for personnel recovery, with the better range and reception from their Jungle Antenna helping them get found (along with a sound recovery plan).

But the most important reason that transcends all the others is the fact that you’re using something you learned to build yourself. You built it, you learned it works, and now you have that confidence in yourself and your equipment you wouldn’t have any other way. That confidence is earned through training.

Brushbeater: Directional Antennas for the Small Unit, Part II

NC Scout at Brushbeater has Part II of Directional Antennas for the Small Unit.

The use of Directional Antennas are the most basic way to improve communications security even if all you’ve got is a set of inexpensive radios. In Part 1 we talked about the theory of use and why they’re important to have for the dedicated RTO of a small unit. Sending your signal in one direction versus all directions does a couple of things for us- creates security through only sending a signal along the necessary path and second it greatly improves the range along that path. In this section we’re going to discuss the antennas themselves and how they work.

The Yagi

UHF Yagi in the field during the Advanced RTO Course.

Remember just a few years back when every house had those funny antennas on its roof? The ones you had a rotor (or if you were poor you had an set of big channel locks on the pole) to turn to get a better signal on the TV stations you wanted to watch? They’re mostly gone these days but that was a type of Yagi antenna.

Named after two electrical engineers in Imperial Japan during the interwar period, Yagi and Uda, the antenna was a solution to two problems. First, it sent a signal in one direction much further with a lot less power. Second, it listened much stronger in that same direction. It enabled directional communications links with even the very crude radio gear of the day, and found itself in service with the primitive radar systems just coming into use.

Yagis work through having a basic dipole (called the driven element) connected to the radio, with one dipole slightly longer just behind it (called a reflector) and one or more dipoles out front (called directors) that have no electrical connection to the driven element. They work on magnetic harmony- in other words, the reflector reflects the energy from the driven dipole forward, and the directors further pull that energy in the forward direction. The more directors you have, the tighter the beam. In addition, the more directors you have, the higher the decibels of gain you have in that direction- keep in mind that with each 3db of gain, you’ve effectively doubled your radiated power output in that direction. Since gain is in orders of magnitude, for each additional 3db you’re doubling your gain again.

Wait, what? Think about it like this. If you have a three element Yagi antenna, like the one picture above in from the Advanced RTO Course, which has 7.5 decibels of gain, you’ve taken the 4 or 5 watts from a handheld and increased its radiated power to over 20 watts just based on the gain of that antenna, in the direction that antenna is pointed. You’ve taken a very basic tool (the humble handheld) and made a potent communications device while using the same amount of battery power. Not bad. Not bad at all.

But the Yagi also has gain on reception, meaning it hears better in that given direction over a single omnidirectional antenna. That’s why going back to our old over the air TV antenna example above, you’d rotate the antenna towards the direction of the TV station, and why hams use the same antennas on towers to listen in a given direction. Its a heck of a lot of capability in a relatively small package for line of sight (VHF/UHF) use. And since they’re small, they should be part of every patrol loadout.

Moxons

The Moxon is incredibly simple to build.

Similar to the Yagi, a Moxon is a directional antenna that’s wildly simple to build. The best way to describe it is a Yagi with the director removed- a driven element and a reflector. So rather than a tight beam LED flashlight radiation pattern, these are more like a broad maglite. The antenna direction itself is pretty broad compared to the Yagi, but where these really shine is through their simplicity. With just a few pieces of wire and some material for the frame, you can build one in less than an hour and have a directional antenna ready to roll for a team. Check Moxgen for a downloadable program that gives all of the measurements you’ll need for cutting the wires.

Longwire and Resistor

The last directional antenna is known as the Longwire. The Longwire antenna was best known to the Vietnam generation as LRP team members used them for directional communications back to their bases of operations while evading the Signals Intelligence assets of the NVA. As the name would imply, it’s one really long wire that runs to a resistor placed in series with the wire and then driven into the ground. The long wire itself radiates with the ground end running along the earth ground. The resistor works to pull all of the current in its direction and with it most of the radiated energy.

The Longwire antenna rigged up for use. It’s incredibly simple and goes up fast.

Of each of the antennas discussed, the long wire is by far the simplest and most clandestine when used. And it also presents a very low Standing Wave Ratio (SWR) due to the residual energy being pulled to the resistor at the end of the line. Very little gets reflected back to the radio itself, But most of all, it packs up the most compact and is the easiest to build or repair in the field. All you really need is a long run of wire and a high Ohm carbon resistor- just make sure you have a lot of them.

Summing It Up

These three antennas are each fairly easy to build on your own and present a huge advantage over omnidirectional antennas. The security offered through using directional communications is not to be overlooked. For a team of guerrillas communicating critical information, its the only option. But that said it takes a bit of work and training to get right. In part three we’ll be discussing exactly how to do that, covering the basic planning requirements and how to incorporate them into your patrolling equipment.

Here’s a link to Part I if you missed it.

Brushbeater: Directional Antennas for the Small Unit

NC Scout of Brushbeater has an article on Directional Antennas for the Small Unit. Using directional antennas for radio communication can increase the range of communication and decrease signal interception outside the beam path.

One of the biggest misconceptions behind communications security revolves around misunderstanding not just the role of the equipment but also how it functions. A big part of that is the basics of antenna theory. For most radio seems to be a plug and play kinda deal- it either works, or it doesn’t. Antennas are a type of voodoo magic and the solution to security is electronic encryption. Except it isn’t, and doesn’t do anything except mask what you’re saying, but not the fact you’re saying it. Guerrillas must rely on not being detected- and no matter how high tech you think you are, it’ll not solve a tradecraft issue.

The reality is that we’ll be working with equipment that is common and off the shelf- no matter how much we want those microwave NSA-encrypted troposcatter radios made of unobtanium, a big part of local networking is done via plain old VHF and UHF amateur and commercial gear that’s common. Guerrilla communications have to be harder to detect. And at the strategic level when building an underground network, you have to understand how to plan. Even with the cheap equipment most of you likely have, incorporating a level of planning into your local communications will yield a much higher level of security and success. Knowing and understanding directional antennas becomes a key part of that planning, and as we cover in the Advanced RTO Course, there’s several options that each get the job done.

Directional Antennas such as this Yagi seen here offer security by ‘beaming’ our transmission in the direction its pointed.

Directional antennas accomplish two goals for us. First, generally speaking, if you’re not in the direction of the transmission you’re not going to hear the traffic. Because of this it offers a big advantage in the security department. If two directional antennas are transmitting toward one another, they’ll be able to communicate with the only people hearing the full conversation being in the middle of the two people. The second advantage is that instead of all our energy going in all directional at once, as with an omnidirectional antenna, a directional antenna sends the same amount of radiated energy in one direction- greatly increasing our range and signal strength in that direction, so we won’t need nearly as much power to accomplish to reliably communicate over a distance you might not have thought otherwise possible.

Antenna Theory For Non-Technical People

Radio waves travel at the speed of light. So with that said think about your antenna as a type of lightbulb. The more efficient your antenna, the brighter the light (your signal). The more power plus efficiency, the brighter the light and the more range you get. While we measure light in terms of candle power, we’ll measure our signal strength in decibels (db) and our efficiency in terms of gain. Here’s where it gets tricky, but we’ll break it down simple.

A light in the darkness- it the same visual as you would see if an omnidirectional antenna emitted light. That light is a lot like your signal.

Picture yourself in a dark room with no windows. What most people consider antennas could be thought of like lightbulbs in the center of that room. They light it up, but there’s shadowy corners and nothing is as bright as it could be. Where that light goes is just like your signal. And everyone in that room with a set of eyes will immediately know where the lightbulb is. So maybe you don’t want a bright light in the middle of the room, maybe you just want a flashlight to see one corner- to “see” the person you’re trying to communicate with. You’d want a flashlight- and that light directed in one direction will go much further with the same amount of power (or much less) while not lighting up everyone else in the room. That flashlight is a directional antenna.

The antenna you see here is really only half of the picture- the body of the vehicle serves as its groundplane, otherwise known as a reflector. Being in the center of the roof it provides an equal reflection in all directions.

Now let’s explore antenna theory a bit more, now that we have a frame of reference. What most consider an antenna- that thing sticking out of the top of your HT or off the top of your truck, for example, is actually half of an antenna. It is the radiating element- where the signal energy from the radio actually comes out. You could also call this the “hot” side. That radiating element is exactly one half of your antenna. The other half is what’s called the ground plane, which reflects the radiated signal. This would be the “cold” side. So if you’re looking at a flashlight, you’d see the bulb and the mirror behind the bulb. Just as the mirror is a type of reflector, so is that cold side of your antenna. And now the trick is to get that reflector to reflect in the direction we want the signal to go.

Tying the Concepts Together

A directional antenna’s signal would look like this, versus the lightbulb example above.

So just as our flashlight takes a small amount of radiated light and sends it much further than a simple lightbulb in the center of a room would, so does our directional antenna. A lot of folks frequently ask “how much range will this thing get?” when asking about individual radios, and with line of sight gear such as the basic Baofeng, you’re going to get a heck of a lot more in one direction than you would with omni-directional antennas, while greatly improving your own communications security. If you can master the basics while thinking a little bit outside the box, you’ll be surprised at what can be done.

 

Off Grid Ham: Discussing Vertical And Wire Antennas

Here’s an article from Chris Warren of Off Grid Ham, writing about options for DIY antennas – Discussing Vertical And Wire Antennas

A topic so deep and wide.

I messing around with you. There is no such thing as an antenna specifically for off grid radio. But since off grid amateurs tend to be practical, do-it-yourself types, some vertical and wire antennas are more more appealing than others. What are the options, and how well do they work? We can’t possibly cover everything in one article, but we’ll go over the most popular types of antennas for off grid hams and talk about the function of each of them. vertical and wire antennas

Two basic flavors. vertical and wire antennas

There are two basic types of antennas for off grid radio: Vertical and wire. Yes, I am aware that there are many others: Beams, loops, etc. But remember we’re trying to keep it simple, practical, and relevant. A vast majority of hams end up using either a vertical or a wire antenna.

The reasons why are clear. These antennas are easy and inexpensive to build, and (for the most part) really do work. Think about all the advancements in technology. Radios have gone from massive tube farms to computerized communications centers with color displays and features that would have been Star Trek-ish just ten or twelve years ago! But at the other end of the coax, antennas have not fundamentally changed over the entire history of radio. You can compare a 50 year old ARRL Antenna Book to a 2020 edition and find nearly the same content in each of them. vertical and wire antennas

About the ARRL Antenna Book. vertical and wire antennas

It would be worth your while to own a print copy of the ARRL Antenna Book. It can be very technical and deep, maybe more than what the average ham is willing to digest, but wow, what a wealth of information. When you need to answer an obscure antenna question or look up a way-out-there math equation, the Antenna Book will come through. New copies can be quite expensive. I suggest buying an older used edition for a fraction of the cost. It doesn’t really matter because the information essentially never changes. My personal Antenna Book is nine years old and I have no plans to update it.

I don’t have a real high opinion of ARRL books in general, but the Antenna Book is an exception. It’s stellar. Every ham should own one.

The vertical antenna.

My very first antenna was a vertical, a Hy-Gain 14AVQ to be exact. I bought it used because, well, when you’re fourteen years old cobbling birthday & odd job money together for radio gear, that’s how you roll. The 14AVQ has been in production since at least the 1970s and is still available on the market today. I had a blast with that antenna and made many solid contacts on it. vertical and wire antennas

Vertical antennas offer an omnidirectional signal pattern, take up very little space, and are easy to install. They do not necessarily require support structures such as trees and buildings (I mounted my 14AVQ to a pipe pounded into the ground). Functionally they have a low angle of radiation, which is favorable to DX. There is also some evidence that vertically polarized antennas are better for short range (ground wave) communications.

The cons of vertical antennas. vertical and wire antennas

On the negative side, vertical antennas are harder to home-build and tune compared to wire antennas. Complicating that, commercially made verticals can be expensive. The Hy-Gain 14AVQ of my youth sells new for about $230.00. That’s a lot of money for what is essentially just an aluminum pole with some coils in it. The research & development costs, which I acknowledge can be very high, were amortized off the books decades ago. With that debt long paid off, the 14AVQ represents huge profit center for the manufacturer. This pattern can be repeated for almost any commercially made vertical antenna. Once the R&D costs are recovered, these antennas are basically money presses for the manufacturers.

Lastly, vertical antennas usually require ground radials. Where will you put them? If your antenna is mounted at ground level, you can just bury them in the dirt. Roof mounted verticals may be more tricky. There is no absolute rule for how many ground radials are needed, but more is better.

Wire antennas.

vertical and wire antennas

PUBLIC DOMAIN GRAPHIC

There is little to dislike about wire antennas. They can be easily made from materials most hams already have around the shop. Wire antennas done right really do work! The dipole is the “Mother antenna,” the antenna all others are based on. Wire antennas can be bent and shaped to fit your space. If you have to bend or droop a wire, it’s generally not a problem. Horizontal wire antennas also have a low angle of radiation, but it is dependent on elevation from the ground. This is why amateurs interested primarily in NVIS communications should not mount their wire antennas more than 30-50 feet up. There is such a thing as “too high”.

The bad news.

Wire antennas have two main disadvantages. First, they usually require two or more support structures. For a fixed station, this means having buildings or trees in the right places to hold your antennas up. For portable use, it means picking a site with trees or other tie points, or bringing a support system with you. By the way, many public parks prohibit affixing anything to natural features, even temporarily. Be respectful and verify what you’re allowed to do before you start tossing wire up in the trees.

Although wire antennas can sometimes be bent and shaped to fit a defined space, doing so may affect performance. Antennas are designed to be a certain shape for a reason. Anything that messes with the physics of an antenna is going to change the way it works. Changing the original shape of a wire antenna does not necessarily degrade performance, but it may result in a situation not favorable to your operating needs, such as when the radiation pattern is altered. Many hams have no choice and must do some antenna gymnastics to make their stations work. Although imperfect, these alterations are usually tolerable.

What about store-bought wire antennas?

I generally advise against buying commercially-made wire antennas. They do work well, but with a few exceptions they are not a good value for the money. One well known company is offering a portable “tactical dipole” for $400.00. Granted, it’s very well planned with a slick carry case and other handy features, but in the end it’s still just a dipole. A four-hundred dollar dipole! This illustrates a trend in the prepper/survivalist community where including the word “tactical” in a product name makes that product cost 3-5 times as much as it should.

The “Hail Mary” random wire antenna.

Wire antennas have one more big plus. A “Hail Mary” antenna can be any available length of wire. In more formal language, they’re called random wire antennas and they are exactly what the name implies. In an emergency, you can literally toss a random length of wire out the window, correct it to 50 ohms as best you can with an antenna tuner, and go. It won’t be very efficient, but you will get a signal out.

I have a random wire antenna as part of my go-kit. It works surprisingly well with my 5 watt FT-817. It would never be my first choice, but I’d be very happy to have it as a last choice.

Resources.

QSL.net has this amazing wire antenna reference that lists nearly 400 different wire antennas and diagrams on how to make them. Some of the designs are kind of way out there and I’m not sure they would work, but experimenting is part of the fun. The website cuts out complicated math and lengthy explanations; it just gives short & simple recipes on how to make some great antennas.

WA2OOO has a very cool calculator to determine the size of several popular wire antennas.

AmPart: RTO’s Guide to Connectors

NC Scout at American Partisan has a nice, short article on radio cable/antenna connectors and what is useful for improvising antennas — RTO’s Guide to Connectors.

One of the common questions I get before, during and after the RTO Course is “how in the heck do you remember all those different connectors?” Well, the answer is nothing more than repetition- I know them because I’m built so many antennas over the years and needed the various connectors you come to know what they’re called.

Its a good idea to have a large number of spare connectors and adapters on hand. If you’re making external antennas for your equipment, they’re an absolute must have item. And unlike pretty much everything else we make our antennas from in the RTO Course, they’re the hardest to source in a working environment, so knowing what they are and having a bunch on hand now makes too much sense.

Cobra Heads make improvised antennas fast and simple.

The Cobra Head 

A story I tell in class is exactly how I discovered the real name for what I always knew as a Cobra Head. The Split Post BNC Adapter, or BNC Banana Jack Adapter, is widely known to Army guys as Cobra Heads- in fact, I never knew they were called anything else and couldn’t find them for a long time after I got out. I found them at a Hamfest in a big tray of connectors and felt like an idiot when I was told what they’re really called. It didn’t matter- I found them.

Why they’re important is that its the easiest connector to use when building improvised wire antennas. We were given them by the bagful in the Army to practice antenna building, and I came to really appreciate it. Simply cut your wire, match the radiating wire to the red end and ground side to the black, loop it around and you’re good to go. If you want to get the most secure with it be sure to use some ring terminals to connect the wire to the connector. Attaching BNC coax can’t be easier and more secure…

Click here to read the entire article at American Partisan.

American Partisan: Home Brew – NVIS Antenna

Johny Mac at American Partisan has an article up at American Partisan on making your own NVIS antenna. A near-vertical incidence skywave (NVIS) antenna is used in the high frequency (HF) spectrum from around 1.8MHz to  10MHz in order to cover an approximate radius/range of 300 miles. HF is usually used for long distance communication around the world, and most antennas are built to maximize range, but those antennas can often cause the radio signal to skip or make a gap in the range from about fifty to three hundred miles.  The NVIS antenna redirects the radio signal in such a way that it covers that gap at the sacrifice of the longer distance contacts. This makes the NVIS antenna ideal for communications during a regional disaster.

If you do not know what a NVIS antenna is and why it is a great addition to your antenna farm, go and read these four articles. The first being from NC Scout titled, Near Vertical Incidence Skywave – Simplified, then NVIS I, NVIS II, and NVIS III authored by Key Pounder and published on NC Scout’s site, Brushbeater.

At a 100,000-foot level though, a NVIS antenna is a dipole antenna that has a steeper transmit angle than a traditional horizontal flat-top dipole antenna and is located closer to the ground at between 8 to 15-feet Vs. a traditional 1/4λ height; let’s say 30 to 60-feet over tera firma. This allows you to transmit to other stations closer to your AO that you may skip over using a flat-top horizontal dipole antenna. Think of the skip bounced off the ‘F’ layer of the ionosphere being 25 to 50-miles Vs. 200 to 300-miles. The German Army developed this procedure during WW II to communicate with troops via the airwaves closer to the transmitting station.

Traditional dipole antenna radiation Vs. NVIS radiation

I started out building my NVIS antenna using the directions posted on the DX Engineeringsite as my blue-prints for the project. Although you can buy a kit from DX Engineering, I had plenty of hardware around the redoubt so I decided to save a few bucks. Below is my Mise en place for this build. Hams are the true scroungers of this earth…

Click here to read the entire article at American Partisan.

AmPart: Directional Antennas for the Small Unit, Part I and II

NC Scout at American Partisan has started a series of articles on antenna theory called Directional Antennas for the Small Unit. If you’re just getting started in radio communication, or you’ve been using it for a while but haven’t spent much time getting to know your antennas, this is a good start.

Directional Antennas For The Small Unit, Part 1

One of the biggest misconceptions behind communications security revolves around misunderstanding not just the role of the equipment but also how it functions. A big part of that is the basics of antenna theory. For most radio seems to be a plug and play kinda deal- it either works, or it doesn’t. Antennas are a type of voodoo magic and the solution to security is electronic encryption. Except it isn’t, and doesn’t do anything except mask what you’re saying, but not the fact you’re saying it. Guerrillas must rely on not being detected- and no matter how high tech you think you are, it’ll not solve a tradecraft issue.

The reality is that we’ll be working with equipment that is common and off the shelf- no matter how much we want those microwave NSA-encrypted troposcatter radios made of unobtanium, a big part of local networking is done via plain old VHF and UHF amateur and commercial gear that’s common. Guerrilla communications have to be harder to detect. And at the strategic level when building an underground network, you have to understand how to plan. Even with the cheap equipment most of you likely have, incorporating a level of planning into your local communications will yield a much higher level of security and success. Knowing and understanding directional antennas becomes a key part of that planning, and as we cover in the Advanced RTO Course, there’s several options that each get the job done.

Directional Antennas such as this Yagi seen here offer security by ‘beaming’ our transmission in the direction its pointed.

Directional antennas accomplish two goals for us. First, generally speaking, if you’re not in the direction of the transmission you’re not going to hear the traffic. Because of this it offers a big advantage in the security department. If two directional antennas are transmitting toward one another, they’ll be able to communicate with the only people hearing the full conversation being in the middle of the two people. The second advantage is that instead of all our energy going in all directional at once, as with an omnidirectional antenna, a directional antenna sends the same amount of radiated energy in one direction- greatly increasing our range and signal strength in that direction, so we won’t need nearly as much power to accomplish to reliably communicate over a distance you might not have thought otherwise possible…

 

Click here to read the entire article at American Partisan.

Click here to read Part II at American Partisan.

American Partisan: The Jungle Antenna Revisted

NC Scout at American Partisan has written another article discussing the jungle antenna – The Jungle Antenna Revisited: Task and Purpose for the Partisan and Prepper. NC Scout has written about this antenna and its usefulness previously.

Going back to the early days of the Brushbeater blog, the Jungle Antenna post has been and continues to be one of the more popular posts I’ve done. And for good reason- I wrote it to be used. It’s the antenna every student in the RTO course builds and one of the designs they get hands on with, and it’s the one that they know works from the demonstrations we do with them. But often, as with everything, a context for the task and purpose has to be clarified.

Many preppers who contact me fall into a similar trap. I have a goal and recognize a need. What can I buy that does for me what I want it to do? How do I do this in the most cost-effective way? And finally (but what should be first) how do I obtain the skill to best use the gear I’ve purchased? It’s a problematic point of view for a lot of reasons but one I get frequenct questions about nonetheless. And that’s ok. I’ll normally answer it the same way- Use your stuff. Learn to use it even better, and never stop!

One of my objectives bak then, as it remains in my classes and writing today, was emphasizing the skill of building your own equipment…

Click here to read the entire article at American Partisan.

Brushbeater RTO Course – Why You Should Take It

One of our members recently attended the Brushbeater RTO Course. He has written up his thoughts on why you should take the RadioTelephone Operator course if you can.

Earlier this month I attended Brushbeater’s RadioTelephone Operators course taught by NC Scout. Other people have done reviews of the class (see here and here), so I am going to structure this a little differently. Rather than give a blow by blow of the course as others have already done, I’ll try tell you why you, as a prepper, or member of a Neighborhood Protection Team (NPT), or member of a Mutual Assistance Group (MAG), should take this course.

The purpose of the RTO course is to teach you how to communicate via radio and do so effectively as a member of a communications team. Communication is the act of transferring information from one place to another. Successful communications means that the information has been correctly and effectively transferred from the sender to the receiver. How many ways can that go wrong in radio communication? You may be surprised. The RTO class attempts to identify and rectify some of those common problems.

First, you may not be talking to the right person in the right place. For this, you need a communication plan, or Signals Operating Instructions (SOI). The plan tells you how to identify/authenticate to whom you are talking. It tells you where (what frequency) to contact them. If you can’t speak to them on that first, primary frequency, then you have an alternate frequency and then a third, contingency frequency. Finally, the plan lays out an emergency method of communication. You may have one plan that you use week in and week out for practice with your team or for supporting public service events, but you should practice changing it as well. And if you are preparing for some sort of TEOTWAWKI SHTF WROL WTFBBQ where your NPT is fighting off the golden horde type of event, you’ll want to change it every day.

Choosing the correct frequencies for the location and distance across which you need to make contact is a part of this planning, too. Will line-of-sight frequencies be appropriate or are beyond-line-of-sight frequencies required? What frequencies do everyone’s radios cover? To what frequencies does any possible adversary have access? If our radios cover a frequency, is the antenna on the radio sufficient to make the contact? If not, can you build a field expedient antenna that will be better?

Make sure you can talk to the person you want, and that it actually is the person you expect – check.

Next, you need to transfer all of the information without forgetting or leaving out anything important. Here the RTO course emphasizes standardized report formats. Most of these have come from NC Scout’s prior military experience. You can modify these for your own group or make up new ones; the important thing is to standardize them and to not modify them to leave out anything important. Many experienced radio operators or prior-military service personnel are familiar with the SALUTE report (size, activity, location, uniform, time, equipment) for reporting enemy information, but there are many other useful reports as well.

A good example is the arrival report, used to tell the command element that you have arrived at the location where you were sent. In my own experience with public service and emergency response, your arrival is typically only sent with something like, “Net control, this is Wxxxx. I have arrived at Spokane Memorial.” While having an entire report for arrival, may take more air time, it can convey critical information. For example, you can add that there was a rollover accident blocking interstate 90 so take the 5th Ave exit to get to the hospital. Or you were sent to the Red Cross building on McClellan, but they had moved services a few blocks away to the high school at 5th and Stevens and you taking up your post there. Deviations in final position as well as deviations on your route the location can provide important information for higher up decision makers and shouldn’t be left out.

The RTO course covered and practiced sending and receiving several different types of eports. Just as important as sending all of the information is receiving all of the information accurately. NC Scout emphasized that the receiver should repeat back the entirety of the report to the sender to ensure accuracy. Just saying, “Report received” doesn’t cut it and results in time wasted, or worse — lives lost, because a response was sent to the wrong location or the wrong assets were delivered.

Make sure that all important information is accurately delivered – check.

Finally, if your group or team is going to run efficiently and effectively, your command and control must be organized. Units being sent out must know why they are being sent and what they are expected to accomplish. The command element/post must remain available and actively monitor any operations in progress. Enough radio operators must remain with the command element to communicate with all of the remote units without being overwhelmed. How many radio operators that is will depend on your specific circumstances, including your size, the number of remote units to be sent out, the type and size of the situation to which you are responding, the capabilities of the radio operators and so on. For example, a command center for a peacetime parade may have one radio operator, communicating with twelve remote radio operators, but a large marathon may have several different teams operating on their own frequencies with their own net control. Similarly, a Neighborhood Protection Team with one control point and one roving patrol can operate with one RTO in the command center, whereas a community under siege in a civil disturbance scenario may have several scouting teams out and a need for a command center RTO for each remote team.

The RTO course again uses some military procedures to help with the command function. Warning orders and operations orders are briefly discussed as methods to impart the goals and mission-specific procedures to the teams being sent out. Similarly, NC Scout briefly discusses what are intelligence and intelligence requirements and the inclusion on the requirements in mission briefings.

Control your communication teams effectively – check.

The RTO course teaches to all levels of experience. If you are new to radio communications, the class will cover the basics of radio operation, antenna theory, and propagation for line of sight and beyond line of sight communications at a level that is understandable for a beginner, yet provides insights to more experienced radio operators as well. The class I was in had people from no prior radio use at all the way up Amateur Extra ham radio operators and ex-military radio users. Everyone appeared to have gained something valuable from the class.

In a disaster or SHTF scenario, you will need to talk to someone. That someone likely won’t be standing right next to you all of the time. How are you going to talk to them when they aren’t in talking distance? Why might you use UHF instead of VHF to talk to them? Why might you need HF? Why might you want to use a digital mode instead of FM or SSB? What’s the best radio for my team? Who needs to have a radio? Who needs to know how to use one? Should you use FRS or MURS? Should you get an amateur radio license? Is burying a box of Baofengs enough to cover my communications needs in the future? If you’re not sure about the answers to any of those questions, or are confused about what some of them mean, then you should take this class.

Occasionally I teach classes for people to get their Technician amateur radio license, and I plan on using some of NC Scout’s antenna explanations in the next class. The training about reports has made me re-evaluate how our radio communications should be conducted. I drove seven hours for the class, and it was worth it.

Related:

Brushbeater: Scenes from a Recent RTO Course

Dialtone: Puzzle Pieces – Gear to have in your kit for field expedient antennas.

Covert and Hidden Antennas

Sparks31 has a brief article up on Covert and Hidden Antennas.

Whether you are setting up a field radio station for communications or a monitoring post for SIGINT operation, the antenna is the linchpin of your setup. The best radio in the world is useless without a decent antenna.

Let’s take a look at a common antenna design, one I’ve used with much success over the years:

discone-vhf-uhf-hardline

This is a discone antenna. I have one at my eastern QTH. For a first antenna it’s not bad. It makes an adequate wideband receive and transmit antenna for the VHF and UHF bands. It’s a unity gain antenna, but its advantage is that you can get on the air with multiple VHF and UHF bands with a single antenna. For permissive urban and suburban environments it’s a good choice.

However, it sticks out like a cow in church. Anyone with a modicum of RF knowledge will know what you’re doing when they see one on your roof. Not a problem in permissive environments like the U.S. today, unless you live in place that has a H.O.A. which restricts antennas, or for whatever reason(s) you want to keep your RF activity under wraps.

Antennas are one of those things that you can easily roll your own out of whatever stuff you have lying around your workshop, homestead, or wherever.

Marconi spins in his grave every time a ham buys an aerial instead of building it.
– Joe W1GFH

Continue reading “Covert and Hidden Antennas”