VIDEO
Many amateur radio enthusiasts spend countless hours experimenting with different HF antennas, hoping to find that perfect setup that delivers exceptional performance. Claims about antenna effectiveness abound—some glowing, others less so—but what works brilliantly for one operator might disappoint another. This puzzling inconsistency has long intrigued the ham radio community. After decades of experience and numerous antenna trials, I believe there is an additional, often overlooked mystery factor that influences how antennas perform in different locations. This unknown factor could be the key to understanding why certain antennas excel in one place but underwhelm in another.
In this article, I’ll share insights gathered over more than 60 years of HF antenna experimentation, reflecting on both my own experiences and those of fellow hams worldwide. I’ll also delve into how geography, local environmental conditions, and even Earth's magnetic field might play a role in antenna performance. Whether you're a newcomer puzzled by which antenna to choose or a seasoned operator curious about optimizing your station, this exploration of the "mystery factor" in HF antennas should offer fresh perspectives and food for thought.
My Weekend and a Quick Ham Radio Update
Before diving into antenna specifics, I’d like to share a little about my recent activities, which remind me of the vibrant life around ham radio. Over Easter weekend, I accompanied a friend to A&E, visited a railway museum—something I hadn’t done in nearly 30 years—and then traveled to Portsmouth to see my granddaughter off. She joined the Royal Navy about 18 months ago and was leaving on her first deployment aboard the HMS Prince of Wales, a massive aircraft carrier. Her journey will span eight months, visiting places like Singapore, Japan, and Australia. It’s quite the world tour, and I’m eager to hear her stories when she returns in December.
Back to ham radio, I’ve recently been reflecting on antennas, especially HF (high frequency) antennas, and how unpredictable their performance can be. Over the years, I’ve built many homebrew antennas and tried some commercial ones too, with varying results—sometimes pleasantly surprising, sometimes frustrating.
The Curious Case of Vertical Antennas and Elevated Radials
One interesting development comes from my friend Brian (call sign ZL3XDJ), who is based in New Zealand and has been a vocal advocate of vertical antennas. Brian has worked many DX contacts using verticals with great success. Recently, he experimented with raising his vertical antenna’s radials about two metres above the ground instead of laying them on or buried in the soil. The results were impressive.
Brian also configured his radials to form a directive array, swinging two or three radials in a particular direction to enhance antenna gain that way. This technique reportedly provides a significant advantage, rivaling the performance of many radials laid directly on the ground. It’s a clever way to boost directivity and signal strength.
Inspired by Brian’s findings, I tried a similar setup with a 20m vertical antenna and a couple of radials pointed along the long path. Although it did improve directivity, the vertical still didn’t outperform my horizontal dipole. However, switching from grounded to elevated radials consistently gave me an extra one to two S-points on the signal strength, which is a noticeable gain in ham radio terms.
In one test, just a single radial elevated above ground paired with the vertical antenna outperformed a comparable vertical with radials on the ground by one to two S-points. I conducted these tests over about three weeks, monitoring signals via the Reverse Beacon Network and SDR receivers worldwide. This experience highlighted how location and antenna configuration can dramatically impact results.
The Unknown Factor in HF Antenna Operation
Here’s where things start to get really interesting—and mysterious. Many hams have experienced the frustration of installing a new antenna only to find it underperforms, while on another day, the same antenna might yield excellent results. Band conditions, of course, fluctuate, influencing reception and transmission, but could there be another hidden variable at play?
One of the best ways to judge an antenna’s true effectiveness is through long-term, regular operation rather than single-day tests. Over time, patterns emerge that help separate good antenna design from the whims of propagation conditions.
Personally, I’ve been very happy with my half-size G5RV antenna, also known as a doublet, which I keep about 28 feet above ground level. This height means it doesn’t produce low-angle radiation, but I’ve found it performs well for most DX contacts, including long path signals to New Zealand. Some operators swear by end-fed half-wave (EFHW) antennas; others dismiss them as noisy or inefficient. Even the RSGB has published critical views on EFHWs, suggesting they cause interference and noise. However, in recent years, many hams have found EFHWs easy to erect and surprisingly effective.
What this boils down to is that there is no one-size-fits-all antenna. Different antennas work well for different people, and the reasons aren’t always obvious.
Geographical and Environmental Influences on Antenna Performance
Why do vertical antennas work wonders for Brian in New Zealand but don’t perform as well for me here in Essex, England? I’m located about three or four miles inland from the coast, whereas Brian is closer to the sea, though not right on the shoreline. Could proximity to the sea or other geographical features like hills and mountains influence antenna performance?
Mountains, for example, may reflect radio waves and enhance signal strength in certain directions, a phenomenon I’ve personally observed during operations in Scotland. Coastal areas, with their saltwater conductivity, can also improve ground-wave propagation and antenna efficiency, especially for verticals that rely on ground radials.
There is another fascinating possibility: the Earth’s magnetic field. Some suggest that magnetic field orientation varies globally and may affect antenna performance. In some parts of the world, the magnetic field might be more horizontal; in others, more vertical. Could this impact how antennas radiate or receive signals? It’s a complex question without definitive answers but worth considering.
Modeling Software: Helpful but Limited
Many hams use antenna modeling software to predict how antennas will perform. These tools are excellent for education and initial design, but free or cut-down versions often lack accuracy. Even the best modeling can’t fully account for all real-world variables like soil conductivity, nearby structures, or those mysterious geographical factors.
So, while modeling is useful, it shouldn’t be the sole basis for antenna decisions. Real-world testing, patience, and willingness to experiment remain essential.
The Challenge of Determining Radiation Angle
Another common topic among hams is the "angle of radiation" from antennas. It’s often said that low-angle radiation (around 5 degrees) is best for DX (long-distance) contacts. However, in practice, many operators, including myself, achieve excellent DX results with antennas that don’t claim to provide low-angle radiation.
For example, a dipole at 28 feet above ground doesn’t technically produce low-angle radiation, yet it can yield strong signals to distant stations. This suggests that medium-angle radiation—perhaps 20 to 25 degrees—is important for long-distance propagation via chordal hops or other ionospheric paths. Determining the exact angle that works best at any given time is challenging and rarely straightforward.
Embracing the Surprises and Unknowns of HF Antennas
All this brings us back to the central idea: there is likely an unknown factor—or a combination of factors—that influences HF antenna performance in ways we don’t fully understand. This factor might be unique to particular locations, depending on geography, magnetic fields, soil conditions, and other environmental variables.
What works spectacularly in one location may be less effective elsewhere, and vice versa. This explains why some antennas get labeled "rubbish" by some operators but beloved by others. The truth is often more nuanced.
If you’ve found an antenna that works well for your location, cherish it. You may have discovered the right match for your environment, tapping into that elusive mystery factor. Conversely, if an antenna doesn’t seem to work for you, don’t dismiss it outright—it might perform excellently in another setting.
Practical Advice for Ham Radio Operators
- Be patient and test antennas over extended periods rather than relying on short-term impressions.
- Consider your local environment carefully—proximity to the sea, terrain, and nearby structures all influence antenna performance.
- Experiment with antenna configurations, such as elevated radials or directional arrays, to optimize results.
- Use modeling software as a guide, but validate with real-world testing.
- Engage with the ham community to learn from others’ experiences in similar or different environments.
- Keep an open mind about antenna types—even those with mixed reputations may work well for you.
Conclusion: The Excitement of HF Operation Lies in Its Mysteries
HF antenna design and operation remain as much an art as a science. The presence of an unknown factor affecting antenna performance adds an element of excitement and challenge to our hobby. Understanding this mystery requires embracing the variability of propagation, the uniqueness of each location, and the endless possibilities for experimentation.
Whether you’re using a vertical, a dipole, an end-fed half-wave, or something more exotic, remember that the "best" antenna is often the one that suits your location and operating style. Don’t be discouraged by inconsistent results or contrary opinions. Instead, enjoy the journey of discovery and keep exploring.
Happy operating, and may your signals always be strong and clear.
About the Author: Peter Waters (G3OJV) is a seasoned ham radio operator with over 60 years of experience. Based in Essex, UK, Peter shares his insights and expertise through his channel and blog, helping fellow enthusiasts navigate the fascinating world of amateur radio.
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