The ‘Other’ VHF/UHF in the Maine Highlands

This is one of a series of “Notes” I published on Facebook. Since Facebook has discontinued the Notes feature, I am publishing that series here on my blog.

Most new hams these days start out on VHF FM and repeaters. Radios are inexpensive and simple to operate. Antennas are small and readily available or easy to build if one is so inclined. Many may never experience any other aspect of ham radio. Those who have entered the fraternity partly or wholly for the hobby aspects of it may get on the HF bands where contacts around the world are an everyday occurrence. Few will ever realize or experience the potential of VHF and UHF using non-FM modes. This ‘other’ VHF/UHF may be one of the best kept secrets in ham radio today.

In Maine, VHF or UHF FM will allow one to communicate up to 50 miles or so between base stations, maybe more if one or both stations are located on hilltops. Operating through repeaters this range is doubled. A few repeaters, especially those located on higher summits, may allow communication between stations up to 150 miles apart. Occasionally, when atmospheric conditions are favorable, the range may be extended. There are linked repeater networks and repeaters linked via the internet which allow long range communication but such contacts are not generally useful for awards or contests and for many, simply don’t provide the same thrill as a radio-to-radio contact without any active devices (repeater, internet, satellite) assisting. There is something inherently fascinating, something often uniquely rewarding, in using natural phenomena to get one’s radio signal to a far-off place.

When we start using modes other than FM – such as SSB, CW and a host of digital modes that work through SSB transceivers – we enter a whole new world on VHF and UHF. This is a world known as VHF “weak signal” communication, but the term can be misleading. Sure, sometimes signals are weak but they can also be extraordinarily strong. Although I am not familiar with the etymology of the term, it may refer to the fact that the non-FM modulation modes can make weaker signals usable where FM would fail. So just what can we do with VHF and UHF once we look beyond FM? Once we get into the VHF range we start to find other methods of signal propagation over relatively long distances; ones that are not useful on the HF bands. The troposphere (the lower region of Earth’s atmosphere which is largely responsible for our weather) has a significant influence, and certain less common ionospheric phenomena come into play. VHF and UHF weak signal communication is almost always done using directional or beam antennas, the yagi being the most popular. Unlike FM and repeaters, horizontal polarization is used. Vertical polarization may have been chosen for FM work to simplify hand held and mobile antenna setups, or because it is easier to achieve omni-directional patterns. Horizontal polarization has certain advantages, among them less susceptibility to many types of man made noise; hence it is a good choice where we may be wanting to copy signals that are not strong. Horizontally polarized beam antennas are also easier to mount without the (usually vertical) support mast degrading performance of the antenna. What is possible on VHF and UHF “weak signal” is influenced by regional weather, terrain and other factors. As a result, this article focuses on what to expect if you live in the Maine Highlands region. This is based on more than 20 years experience. For purposes of this article, the assumption is made that your station is located in a moderate valley, as most of us are. If you happen to live on a hill, you will see better results.

Let’s look at the 6 meter band first. A typical 50 to 100 watt transceiver and a small beam antenna (say, three to five elements on a six to 15 foot boom) will allow contacts to well over 100 miles most of the time. Occasionally this range will be extended by conditions in the troposphere which result in greater signal bending beyond the normal radio horizon. During late Spring through mid summer, the E layer of the ionosphere often becomes ionized enough to reflect 6 meter signals back to Earth. This results in signals propagating over distances to 1400 miles on a single hop, often with excellent signal strength. The band may become full of signals and large numbers of contacts are possible. Less frequent but not uncommon is multi-hop Es propagation. There are usually several good openings from our area to Europe and to the west coast every year during this period. There is a secondary Es season in December-January but more than one hop is relatively uncommon. Aurora can easily reflect 6 meter signals. This is like playing billiards – the signal reflects off the aurora. Typically antennas will be pointed somewhat east of north to work stations to our east, due north to work stations north or south of us, and somewhat west of north to work stations to our west. Contacts out to 1000 miles are common, but greater distances to 1300 miles are occasionally possible. Signals propagated by this method have marked distortion. Single sideband voice may sound very raspy or like a loud whisper. CW signals usually exhibit a buzz or hiss sound rather than a clear tone. Sustained aurora may lead to patches of Es forming and a conversion to auroral Es propagation, wherein the distortion goes away. Meteor scatter, using specialized operating techniques, allows contacts to distances of 1300 miles almost every day of the year. Meteor scatter is of no use for rag chewing but callsigns and signal reports can easily be exchanged. During the peak of intense sunspot cycles, propagation over great distances (even worldwide) is possible using the ionospheric F2 layer, as on the HF bands. There was very little 6 meter F2 propagation during solar cycle 24 due to its relatively weak maximum.

What about the 2 meter band? Using 50 to 100 watts and a multi-element yagi (8 or more elements on a boom ranging from 10 to over 30 feet in length), contacts to 200 miles are possible most of the time. Being in a particularly deep valley will reduce range. Tropospheric enhancement is more common than at lower frequencies, and will at times allow contacts to 300 or even 400 miles. While far less common than at 6 meters, Es propagation does occur on the 2 meter band, usually in June, July or early August. Es contacts to 1300 miles can be made, often with extremely strong signals. In one such opening I worked a station in North Carolina who was running a two watt portable SSB transceiver with its built in telescoping whip antenna. He was blasting in just like a local station! Double hop Es has been reported on a few occasions but is rare. I had one contact at a distance of 1700 miles on double hop Es during my years on 2 meters. Aurora also works well at 2 meters, allowing contacts to 1000 miles and occasionally more. Distortion is even more pronounced at this frequency, usually rendering SSB unintelligible. CW is definitely the preferred mode for 2 meter aurora contacts. Using specialized techniques, meteor scatter works well but is not as easy as it is at 6 meters.

At 135cm, tropospheric propagation is slightly better than at 2 meters. Aurora still works reasonably well. Meteor scatter is possible but quite a bit more challenging. Es is extraordinarily rare but does occur on the order of once every ten years or so! What a thrill it would be to catch an opening like that! I never did.

At 70cm, tropo works quite well. Aurora is somewhat less common than at lower frequencies but can work well during the more intense events. Es does not occur at all, and while meteor scatter is possible it represents a rather extreme challenge.

The bands above 70m are barely used at all in Maine except for a very small number of avid VHF/UHF and microwave contesters. There is so little activity that getting on these bands rarely is worthwhile unless one is an avid contester, has some specific goal in mind, or wishes to explore the fascinating world of microwave propagation.

With high power and larger antennas, other propagation modes come into play. EME, or Earth-Moon-Earth, allows communication with any point on Earth by bouncing signals off the lunar surface. I worked all 50 states and more than 80 countries on 2 meter EME back in the 1980s and 90s when this was all done on CW. One fascinating aspect of EME is that it takes approximately two and a half seconds for a signal to traverse the half million mile round trip to the moon and back. You can actually make a short transmission and then hear your own signal come back from the moon! Tropospheric scatter often allows communication to 1000 miles or more on 6 and 2 meters for stations with a kilowatt of power and high gain antennas (7 element yagi or more on 6 meters, array of four or more long yagis on 2 meters). When I had 1500 watts and a 96 element stacked quad antenna array on 2 meters, I could often work stations up to 1000 miles distant using this brute force propagation mechanism. There is something satisfying about working a station 1000 miles away on a band “everyone knows is dead”. High power and large antennas also extend the range of propagation modes previously discussed. On 6 meter Es I have worked as far as Bahrain, Brazil, Hawaii, and Japan. I have more than 120 countries on 6 meters, all but one or two of them by way of Es propagation. It can be done.

There are several popular VHF/UHF contests. Contesting on these bands is very different from contesting on HF where there are many loud signals all the time. On VHF and UHF you may tune up and down the band(s) for an hour without hearing a signal. When you do find one, you may want to “run the bands” with that station, making arrangements to go from band to band to band, working the station on as many bands as you can. It is both fun and challenging. My first experience with VHF contesting came shortly after I purchased my first 2 meter all mode rig at a hamfest in the 1980s. I had not yet put up a horizontal antenna. I had 90 watts to a quarter wave ground plane I had been using for local FM work. Despite the incorrect polarization making my 90 watts sound more like one watt, I was able to eke out contacts with stations 15o miles away. This opened my eyes to the world of weak signal work and made me want more. It wasn’t long before I made station improvements!

In fact, any operating on VHF/UHF weak signal is different than HF. It’s usually not as easy as turning on a radio and making dozens of contacts. It takes time and patience. Knowledge of VHF/UHF propagation helps tremendously, as you will know when and where to look. On the other hand, the rewards can be great. It is fun to make contacts most hams would believe impossible. There is often a good deal more thrill and satisfaction in making a contact using a rare propagation mode that one must wait for, as opposed to being able to turn on a radio and do it virtually any time.

Cover photo: Temporary VHF/UHF antennas at N1BUG, shortly after a move in 1999. Bottom to top: 13 element horizontal yagi for 2 meters (partially visible); 5 element vertical yagi for 2 meters; 11 element horizontal yagi for 135cm (222 MHz); 22 element horizontal yagi for 70cm (432 MHz) with receive preamp covered by a sandwich bag! The 432 MHz yagi, with approximately 600 watts of power and the preamp shown was enough to work a few dozen stations and all continents on EME, using CW! These antennas were on an azimuth/elevation mount so they could be pointed anywhere in the sky, not just toward the horizon.

An eight-yagi 432 MHz EME array at N1BUG. This array used open wire phasing lines instead of coax to keep losses to a minimum.

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