Ham radio enthusiasts are always on the lookout for antenna designs that offer simplicity, efficiency, and a bit of novelty. One such intriguing design, often overlooked in modern times, is the “upside down vertical antenna.” This antenna type was featured in a 1970 article in RadCom magazine by Pat Hawker, G3VA, and it offers a fascinating alternative to the more common vertical and horizontal antennas used by hams worldwide.
A Walk Down Memory Lane: Rediscovering the Upside Down Vertical
The upside down vertical antenna caught my attention recently as I revisited some classic ham radio literature from the 1960s and 70s. Back in May 1965, I published an article about an inverted L antenna I built and operated from my bedroom. It was grounded and fed from the far end, with horizontal wire running out before descending vertically to ground—complete with buried radials. This practical setup provided vertical polarization, which I found useful at the time.
Pat Hawker’s 1970 article reintroduced me to a similar concept, but with a twist—the antenna was essentially an “inverted vertical,” or upside down vertical. Pat, a well-known and respected author on technical topics in RadCom, was fascinated by this design and shared his insights, which are still relevant today.
Dipoles vs. Verticals: The Ongoing Debate
Pat began his discussion by defending the humble dipole, which many hams prefer over verticals. He argued that a dipole, placed about a half wavelength above ground, can easily match a vertical antenna’s performance, especially for low-angle radiation crucial for DX (long-distance) contacts. This point is worth emphasising—while verticals are often praised for their low-angle radiation, a well-installed dipole can offer equally effective results.
In my experience, vertical antennas work better in some locations than others. For example, Brian, ZL3XDJ in New Zealand, has great success with verticals, whereas I tend to get better results with a horizontal dipole at around 28 feet above ground. This difference highlights how antenna performance can depend greatly on local conditions and personal setup.
Another key insight is that DX signals often arrive at angles higher than the oft-cited 5°. In reality, takeoff angles between 10° and 20° are common due to multihop ionospheric propagation. Even a prominent DX operator I spoke with recently found that lowering his tower from 100 feet to 60 feet—thus increasing the radiation angle—improved his DX contacts. So, the obsession with ultra-low angle radiation is somewhat overstated.
The Upside Down Vertical: Design and Construction
The upside down vertical antenna, sometimes called a T aerial, consists of a horizontal wire section and a vertical wire section. Pat Hawker’s example was built for 40 MHz (around the 7 MHz or 40m amateur band equivalent in modern terms), but the principles apply broadly.
- Horizontal section:: Two quarter-wave legs arranged in a straight line, connected as a single wire roughly a half wavelength long.
- Vertical section: A quarter-wave wire hanging down from the midpoint of the horizontal section.
- Height: The entire assembly can be mounted just a few feet above ground, making it easy to install in small spaces.
One interesting aspect is that the two horizontal legs cancel out their own radiation because they are out of phase, so the antenna’s primary radiation comes from the vertical element. This design provides the benefits of vertical radiation without demanding a towering mast.
- Feeding the Antenna
- Base matching unit: An antenna matching unit (ATU) at the base of the antenna, though this is less popular.
- Balanced feeder line: A balanced feed line runs from the base to an ATU elsewhere, often a quarter wavelength long to position it at a high current point.
- Quarter-wave transformer line: Using the balanced line as a quarter-wave transformer to convert the antenna's high impedance to a lower impedance suitable for coaxial cable. This requires accounting for the velocity factor of the feeder line.
There are three main ways to feed this antenna:
Pat noted that the antenna’s dimensions don’t need to be super precise—some tweaking is expected to get the best match. The essential parts are the vertical radiator and the two horizontal “radials.”
Advantages and Practical Considerations
The upside down vertical antenna offers several advantages:
- Compact footprint: Ideal for small gardens or limited spaces where traditional verticals or dipoles are difficult to erect.
- Simple construction: Can be quickly set up using basic materials and a couple of support poles or a fiberglass mast.
- Self-supporting vertical element: The vertical wire hangs down freely, reducing the need for complex guying or supports.
One practical idea I considered is using a fiberglass pole about 20 feet tall, with the two horizontal radials slanting down at an angle, and the vertical radiator running alongside the pole. This setup could be simple to build and maintain, though the effect of bending radials downward on performance would require experimentation.
Performance and Reception
Pat Hawker’s experience with this antenna was very positive. After converting his 20m dipole to this design, he found it superior for contacts beyond roughly 3,500 miles. Other hams who tested the antenna also reported good results. There was no detailed mention of noise levels, but the antenna’s reception pattern and radiation characteristics seemed promising.
Historically, the T antenna was popular for medium frequency transmissions during the 1930s and 40s, so this design has a proven legacy. While primarily a single-band antenna, some operators have found it workable on other bands, thanks to what’s sometimes called the “AOG effect” (an interesting phenomenon worth looking up for those curious about multi-band behaviour).
Why You Should Try the Upside Down Vertical
This antenna is worth experimenting with if you’re looking for a compact, easy-to-build vertical antenna alternative. It’s not overly complicated, can be quickly erected, and may provide surprising results, especially if you have limited space or want to try something different.
If the antenna doesn’t meet your expectations, reverting to your original setup is always an option. But the upside down vertical could become a valuable addition to your antenna arsenal.
Final Thoughts
Antennas like the upside down vertical show that sometimes looking back at classic designs can inspire fresh ideas for modern ham radio operation. Whether you’re a seasoned DXer or a newcomer to the hobby, this antenna offers a blend of historical interest and practical application.
Experimentation is at the heart of ham radio, and trying out this antenna might just surprise you with its performance and ease of use.
Enjoy your ham radio adventures, and happy experimenting!
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