In previous posts, we’ve looked at DX Engineering THUNDERBOLT® 40/30M and 80/40M vertical antennas. Today, we’ll explore a popular vertical antenna option for working the “Top Band”—one of Ham Radio’s most daunting challenges. A proven choice is the DX Engineering THUNDERBOLT® High Performance 160M Quarter-Wave Vertical Antenna.
With an overall height of only 55 feet, this 160 meter monoband antenna employs a custom-designed “capacity hat” system to give Hams the strongest possible presence at their power level.
What is a capacity hat and what does it do?
When an antenna is shortened from its natural resonant length, the feedpoint becomes capacitive. To offset the additional capacitance, it is common to add inductance in the form of a loading coil to restore the resonance. However, the additional inductor increases the resistance, which increases the loss of the antenna.
A capacity hat, like the large one used on the THUNDERBOLT® 160M, adds horizontal elements to the top of a vertical antenna, which reduces inductor resistance and counters the effects of the shortened vertical antenna. Extensive testing has shown that the improved efficiency and reduced loss resulting from use of a capacity hat can significantly increase the RF power radiating from your antenna.
On the THUNDERBOLT® 160M, the top capacity hat is large enough that the current along the radiator is almost constant. Typical shortened verticals for this band, with smaller top-hats, have currents that vary along the length and end up producing much less signal strength. This also works in the receive mode to let you hear weaker signals, although at this frequency range dedicated receiving antennas are almost a must. A specially designed add-on capacity hat kit is also available for the DX Engineering 80/40M THUNDERBOLT® vertical and 75/80M Full Size Quarter Wave Monoband Vertical antennas.
For owners of mobile vertical antennas, read this blog on DX Engineering’s Hot Rodz® Adjustable Antenna Capacity Hats for select vertical mobile and base station antennas.
Other features of the THUNDERBOLT® 160M include:
- 5 kW SSB and CW rated
- Tunable with an impressive 40 kHz bandwidth, meaning operation on the CW DX frequencies and DX Phone frequencies are within the range of most internal tuners, without physical changes to the antenna
- DX Engineering Adjustable Matching Network configures the lowest SWR
- Lowest possible take-off angle reduces domestic QRM signals
- Engineered with 6061-T8 and 6063-T832 corrosion-resistant aluminum tubing, stainless steel mounting brackets, and stainless steel hardware
- Patented stainless steel Pivot Base for ease of raising, lowering, and making tuning adjustments
- Massive 3 inch OD base section
- Withstands steady-state winds in excess of 50 mph—see manual for guy rope installation and many more details, including mounting pipe (not included) instructions, radial system installation, and suggested parts, such as the DX Engineering Manual Winch Add-On Kit (DXE-VRW-1) that makes raising and lowering the antenna even easier.
DX Engineering recommends installing a minimum of 32, 65-foot-long radials. For detailed installation instructions, other items you will need, and suggested parts, read the instruction manual here.
Enter “Vertical” at OnAllBands for more insights on deciding if an HF vertical antenna is right for your Amateur Radio station.
What do Hams think?
Five Stars: Design—first rate. High-quality components and easy-to-follow instructions. Bottom line so far: This is a substantial and high-quality antenna, well-designed, well-engineered, and relatively easy to assemble and install.
