NVIS Antenna Configurations
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NVIS (Near Incidence Vertical Skywave) is best accomplished transmitting in the most common NVIS bands (80, 60, ad 20m) with a very high angle of incidence, the radio waves going almost straight up. This is the exact opposite of what we are doing when we're "DXing" (distant communications); as a result, almost all the logic we apply to setting up antennas is turned on its head. We must utilized antennas in ways we typically would avoid, and we'll cover the different ways here. The key is to remember we are attempting to direct radio waves upwards, rather than towards the horizon.
Dipole Antennas
These are the most common antennas in amateur radio. They are easy to make and work well. For DX, all you need to do is get them as high off the ground as you can get so the bulk of the radio signals are radiated towards the horizon. Paradoxically, the lower the antenna is hung the more vertical the radio waves tend to radiate. So, simply dropping the antenna closer to the ground (5-10ft even) the more vertical the waves are directed and the better you will perform in the "Cone Of Communication". Keep in mind the resonant frequency of the antenna will change, so keep an eye on your SWR.
Inverted-V Antennas
These function along the same lines as a dipole. the ends of a dipole antenna slope to the ground from a mast in the middle. The mast would be shorter than you'd ideally want for DX communications, no more than 20 feet tall, with the ends being as low as a couple feet off the ground.
Mobile Antennas
You may have experienced (or seen in movies) military vehicles that have a bumper mount antenna that is then arced over the top of the vehicle, often with a rope pulling the tip towards the bumper at the opposite end of the vehicle. This creates an arch over the vehicle, with the antenna radiating a significant vertical component. A flexible antenna with a coil and a spring base could be utilized in this way. After all, the military has been using it since they've been using radio!
Hamsticks
KK4OHF mentioned using hamsticks for NVIS. Rather than using them as verticals, two of them can be used back-to-back, forming a horizontal dipole, either close to the ground or using the vehicle as a 'counterpoise' or ground. Hamsticks tend to have narrow bandwidth, so keep an eye on your SWR, and a tuner will likely be necessary.
Vertical Antennas
While good for DX communications, verticals make extremely poor NVIS antennas in their typical configuration. On the other hand, if a storm has blown your antenna over, the NVIS gods may be smiling upon you! A vertical antenna, tilted at a 45 degree angle will radiate more signal straight up, rather than at the horizon, giving you better NVIS propagation than if it is vertical. Note: unlike a dipole, simply mounting it closer to the ground will not make a vertical antenna more NVIS friendly, unless you also tilt it.
Elevated radials will tend to make the antenna perform better for NVIS. Also, if the antenna if flexible a rope can be attached to the tip and use to pull the top of the antenna downward (similar to mobile antennas), so the vertical becomes an inverted "L", with a significant horizontal component. Obviously, this could damage an antenna that isn't flexible enough, so be careful.
Crossed Inverted-V Antennas
This is an interesting design I would like to try, based upon a military design (AS-2259/GR). Two dipoles, crossing at 90 degrees of each other at a central mast act as both antenna and stays for the mast! One set of wires cut to about 41ft for 60 meters, and another set of wires cut to 31 ft for 40 meters are wired like a fan dipole would be, the wires acting as guy wires and radiators on those two bands. The 40 meter antenna will probably work at 15 meters (DX, not NVIS) as well. While 15 meters may work, an antenna tuner will likely be necessary because the 60 meter legs will interact enough to alter resonance. This design has potential for being adapted to POTA and SOTA, for 20 and 40 meters (which will probably also work well on 15 and possibly 10m).
Horizontal Loop (Skyloop)
This is a loop antenna just above ground level. It works much the same as a regular loop, except being closer to the ground, it has a higher take-off angle, providing NVIS functionality. Loops have an added benefit of being more noise resistant than other antenna designs. These can be difficult to implement as the antenna will be long and difficult to keep relatively level without a series stand-offs.
QRP, NVIS, and 60 meters in EMCOMM
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Low Power (QRP), Near Incidence Vertical Skywave (NVIS), and the 60 meter band looks more and more to be intended for use in Emergency Communications (EMCOMM). I've touched on all of this over the last few presentations, so all I'm really doing here is putting it together.
The recent changes to the 60 meter band embrace the use of QRP on that band. What was the third channelized frequency in the 60 meter band has been eliminated, the frequency spectrum in consumed, and the adjacent portions of the band between the 2nd and 4th channels is now VFO tunable - with the caveat that operation must be QRP (9.15W ERP). The remaining channelized frequencies may still operate at the previous 100W (ERP) level.
The Federal government has set aside portions of 60 meters for inter-agency use as part of their "worst case scenario" plan. Not coincidentally, portions of the band are also allocated for use by various NGOs (Non-Governmental Organizations) and critical infrastructure entities via SHARES (SHAred RESources) HF network. Amateur Radio was/is allowed to use the band on a secondary basis in deference to these other uses.
Amateur Radio's use of the band along with these other users was by design, and with the intention, to create interoperability between Federal, State, and Local Emergency Management and NGOs with the aid of Amateur Radio operators whose skills are often used by the NGOS and Emergency Management Agencies.
While the "professionals" may have access to resources like generators and virtually endless supplies of fuel, Amateur Radio operators will often be required to be very frugal in the use of their resources at home. Transmitting at 5W-20W will extend the life of our power sources, but won't be very effective if we're competing with others who are running 100W-1KW.
Enter the QRP portion of the 60 meter band. Here we have a range of frequencies that are set aside to operate at minimal power. No competing with those higher powered stations. This will hopefully "level the field" for QRP Emergency Communications. Digital and Voice modes can now be operated for DX effectively at QRP levels w/o being blotted out.
60 meters also occupies a "sweet spot" in the bands, between 40 and 80 meters. 80 meters is usually marginal at best during the day. 40 meters is mixed in performance, often losing its NVIS capability as the day goes on, and also lacks the QRP allocation and associated benefit outlined above.
60 meters, on the other hand, is reputed to function more reliably using NVIS throughout the day, and also has the QRP portion of the band. This can't be an accident.
We'll be testing 10, 20, and 40 meters during our next NVIS exercise, but I very much look forward to testing our new 60 meter non-channelized QRP portion of the band to see how well 60 meters will perform at QRP levels using NVIS.
The New 60 Meter Band
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Recent NVIS tests we conducted showed, at least for early daytime hours, 40 meters worked best for NVIS, although both 10 and 20 meters did perform, just not as well as 40 meters. As one might expect, 80 meters did not work well in daytime for NVIS.
Some of us discussed 60 meters, the channelized band, as a possible NVIS candidate. An indication it might perform well is the fact the Federal Government uses it as part of their emergency communications system and SHARES, a public/private emergency communications network.
During those discussions we considered executing a NVIS exercise that included 60 meters. Coincidentally, the FCC has made changes to the 60 meter band, eliminating one of the channels and replacing it
Antenna Polarization
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Our recent NVIS (Near Incidence Vertical Skywave) experiments brought to light a discussion of antenna polarization. Does it matter? Does it impact NVIS? Absolutely and absolutely.
First, lets talk about polarization on VHF. We all generally run vertical antennas when running VHF-FM. It works well when reaching out to repeaters or attempting point-to-point simplex communications. However, if two operators are attempting to communicate VHF-FM and one is horizontal and one is vertical, they will have issues. The E-fields are oriented perpendicular ("cross-ways", so to speak), and the loss of 10db-20db, signal degradation to 1/10th to 1/100th, is the result. It's just the nature of how radio signals are picked up by the antenna. In this case, compatible orientation is vital.
Know Your Gear
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We discussed standardizing channels in a previous ARES net (and also at a recent WGARS meeting). Why? Consistency makes for an easier time dealing with unusual circumstances; not having to spend time and mental effort finding the right channel.
Even more important is to understand how to operate the radio. Here are a few items to be sure you know how to do:
Power
Obviously the most important thing to know how to do.
The Display
Do you know what all those little symbols on the display mean? At least the important ones? It's a good
Amateur Radio, ARES, and RACES
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In previous ARES presentations I have made reference to other entities that either provide Emergency Communications services, or need the ability to utilize them during an emergency.
While we focus on the Amateur Radio Emergency Service (ARES), sponsored by the ARRL, for providing emergency communications, the only entity recognized formally in FCC regulations is the Radio Amateur Civil Emergency Service (RACES). So what is RACES, and why do we hear so little about it?
QRP And Amateur Radio
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While many operators tend to operate using the 100W or 200W their radio provides, and yet others use external amplifiers to run hundreds, even more than 1KW, there are others who operate at the other end of the spectrum, 5-10 Watts.
QRP operation is often practiced by operators participating in Parks On The Air (POTA) or Summits On The Air (SOTA), who are often hiking or backpacking their equipment to the operating location, carrying their power source with them. Naturally, packing a Marine Battery would be a bit of a challenge, so smaller and lighter batteries with lower power capacity are used.
Due to limitations in available power the operators naturally run less power, usually 20W or less. QRP is generally considered 5-10W, but even 20W is possible with more efficient modern equipment and Lithium batteries.
Disaster Preparedness Month 2025
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September is National Preparedness month, and we'll continue our discussion of preparedness. It is fitting we cover the topic as a group, but even more so at home with your family.
Recent discussions have included a variety of people volunteering information about their preparation efforts (or lack of). The most recent West Georgia Amateur Radio Society (WGARS) featured a discussion between Sierra (K4SBE) and John (WD8LQT) regarding her deployments to disaster areas. That discussion focused on catastrophic events where, quite frankly, there is little any of us could do beyond wait for help (i.e. houses destroyed, infrastructure inoperable, etc). Probably the best advice for these types of events, especially if we know they are coming, is to wear a full set of clothes, even when going to sleep - so if something does happen you have some basic personal protection from the elements! We hope to have a video of that discussion available soon.
Third Party Traffic
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When we discuss Amateur Radio and handling traffic, either formal or informal, we tend to think of actual Amateur Radio Operators at the microphone, key, or computer passing information. However, particularly when moving tactical traffic, it may be beneficial to let the third party have the microphone, or type the message into a Winlink email.
Section 97.115 provides for allowing third party traffic as long as the control operator, a licensed Amateur Radio Operator, is in control of the station and monitoring the activity. All requirements that would apply to a typical contact would apply (identifying at proper intervals and at end of communication, use of non-coded communication, avoiding profanity, etc).
Will We Or Won't We (Deploy)?
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During Field Day (2025) a discussion of work being done outfitting the WGARS communications trailer digressed into a debate of whether Amateur Radio operators would ever really be deployed in a local emergency. One operator insisted it would never happen, while another acknowledged the probability was low, but it was not outside the realm of possibility.
The discussion was mostly centered around the fact that post 911/Katrina government communications systems are better integrated, allow various levels of inter-department and inter-agency communications
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