VHF Is Wide Open — Are You Listening?
28/08/26 15:36
The past few weeks have been an absolute blessing for VHF enthusiasts!
With a large dome of high pressure settling over much of the country, we have experienced some outstanding tropospheric enhancement and ducting. Band conditions have been intense, producing remarkable long-distance contacts across VHF and above.
And while SSB weak-signal operation has naturally been producing the greatest distances and some incredible DX, what really demonstrates the strength of these openings is what we have also been seeing on 2-meter FM.
When operators using ordinary FM equipment and vertical antennas are suddenly working stations hundreds of miles away, you know Mother Nature has opened the door!
Local hams have been making contacts as far away as Iowa, Georgia and Florida on FM, while those of us operating SSB and weak signal have been taking advantage of even greater range and opportunities.
If you are not exploring VHF and above for DX, you are missing out on a tremendous amount of excitement and fun.
My Own Experience
Even with my limited operating time, my mornings during these openings have been extremely productive.
On 2-meter FM, I made contacts approaching 450 miles. I unfortunately missed the Iowa contact. I could hear the station, but from my mobile station with a 5/8-wave vertical, I simply wasn't going to get heard over all the other stations trying to make the contact.
And remember — that's FM with a vertically polarized mobile antenna!
The following day I managed to work Mississippi, Georgia, Florida, South Carolina, Louisiana and Oklahoma, along with stations throughout Texas.
Meanwhile, SSB weak-signal activity was even more productive. That's exactly what we would expect. With horizontally polarized directional antennas, lower-noise receiving systems and the inherent weak-signal advantages of SSB, operators can take much greater advantage of an enhanced propagation path than we normally can with typical FM mobile installations.
So don't look at those FM distances as the limit of the opening.
Look at them as an indication of just how good the conditions really were.
If FM signals are traveling several hundred miles, it's time to get on SSB and start looking for some serious DX!
WATCH THE WEATHER!
One of the simplest things you can do to improve your chances of catching these openings is to start paying attention to the weather forecast as part of your operating routine.
When a strong high-pressure system is forecast to settle over a large region for several days, start watching the VHF, UHF and microwave bands closely.
High pressure alone doesn't guarantee an opening, but the stable atmospheric conditions and temperature inversions often associated with these systems can produce excellent tropospheric enhancement and, under the right circumstances, strong ducting.
Signals that would normally disappear beyond the radio horizon can suddenly travel hundreds — and sometimes considerably farther — than we normally expect.
Don't wait until someone tells you the band is open.
Turn the radio on and listen!
Check the SSB calling frequencies. Listen for distant beacons. Check FM simplex and even distant repeaters. Watch propagation reports.
If you're suddenly hearing stations, repeaters or beacons that normally aren't there, get on the air!
THE N5XO PROPAGATION PROJECT
I've also been working on a project designed specifically to make recognizing these conditions easier.
I wrote a standalone propagation-monitoring program that combines multiple sources of information to estimate current, real-time band conditions.
Rather than relying on a single propagation indicator, the system evaluates several types of data, including information from sources such as National Weather Service data, APRS activity, WSPR observations, solar and space-weather information, and other propagation-related sources.
The goal is simple:
Take a large amount of complicated propagation information and turn it into something an operator can understand at a glance.
The system evaluates the individual amateur bands from 6 meters through 3 centimeters, giving the operator an indication of the current conditions on each band.
It also provides a list of radio beacons that, based upon the selected band and current conditions, should potentially be within reception range.
That gives us something extremely valuable.
Instead of the computer simply saying, “Conditions look good,” it gives the operator something to actually go listen for.
During my testing over the past several weeks, I've been very pleased with how closely the program's indications have tracked the actual conditions I've observed on the air. There is still additional testing, refinement and development underway, but so far it has proven to be a useful and dependable tool for recognizing when conditions are becoming favorable.
AND WE'RE TAKING IT TO THE WEB
The standalone N5XO propagation program will eventually be made available for download.
But that's only part of the project.
I'm also developing a server-based propagation engine that will allow our club website to display current propagation information directly in a web browser.
The goal is to give club members an easy-to-read, continuously updated picture of propagation conditions centered around Grid EL09, without requiring everyone to install and configure the standalone application.
Ultimately, I want a member to be able to open the club webpage and quickly answer four questions:
What's open right now?
Which band should I be operating?
What kind of distance might current conditions support?
Which beacons should I be able to hear?
That's where we're headed.
SSB IS WHERE THE REAL FUN BEGINS
If you're currently operating only FM on VHF, give weak-signal SSB a try.
FM DX during a major opening can be tremendous fun, and working a station several hundred miles away from a mobile is something you'll remember.
But SSB opens an entirely different level of VHF operating.
A horizontally polarized directional antenna, low-loss feed line and an all-mode radio can dramatically increase your effective weak-signal capability. Add some antenna height and careful station design and you'll begin discovering just how far VHF signals can really travel.
You don't need a monster station to get started, either.
During strong propagation events, remarkable contacts can be made with surprisingly modest equipment. And even under less-than-ideal conditions, a well-designed station, patience and good operating technique can produce some very respectable DX.
That's what makes weak-signal operating so addictive.
HF propagation is fascinating, but VHF, UHF and microwave weak-signal operation is an entirely different world. Tropospheric enhancement, ducting, Sporadic-E, meteor scatter and other propagation modes can suddenly turn what appeared to be a dead band into a highway.
Sometimes an opening lasts hours.
Sometimes you have only minutes.
You have to be there when it happens.
So watch the weather. Watch the propagation indicators. Learn the calling frequencies. Learn where the beacons are located.
And when you see that big high-pressure system settling in over your part of the country, don't just check 2-meter FM.
Fire up the SSB station, point that beam down the path and start calling CQ.
You may be amazed at who comes back.
73,
Greg – N5XO HAMster Weak Signal Group
