Inverted vee antenna
A space-saving dipole variant with legs bent downward toward ground.
The inverted vee antenna is a variation of the horizontal dipole, with its two legs angled downward toward the ground, usually forming a 90- or 120-degree bend. When viewed from the side, it looks like an upside-down letter "V," which is how it got its name. This design is often chosen where space is tight, because it shrinks the antenna’s ground footprint with little loss in performance.
For installation, the inverted vee needs only a single tall support at its center. The ends are insulated and fastened to anchors near ground level or, if mounted on a house, near the roofline. This setup shortens the distance between the ends. For instance, a full dipole for the 80-meter band needs about 140 feet (43 meters) of ground length end to end, while an inverted vee with a 40-foot (12-meter) apex height requires only 115 feet (35 meters). For amateur radio operators on small lots, this saving can make lower-frequency bands usable.
In theory, the gain of an inverted vee is close to that of a dipole at the same height, because most radiation comes from the high-current center section. Since both antennas have their centers at the same elevation, performance differs little. Free-space modeling software predicts a maximum gain of 2.15 dBi for the dipole and 1.9 dBi for the inverted vee. In practice, however, ground proximity, ground conductivity, and end effects reduce the inverted vee’s efficiency more than the dipole’s. Using the 40-foot example and a take-off angle of 40 degrees above the horizon, the inverted vee produces a maximum gain of 1 dBi in a circular pattern, while the dipole yields an oval pattern ranging from 6 dBi off the sides down to 1.2 dBi off the ends. Raising both antennas higher reduces this gap, but given practical, legal, and financial limits on most installations, the inverted vee is typically 2 to 4 dB weaker than a dipole. Still, when space is limited, an inverted vee can allow operation on frequencies that a full-sized dipole would not fit.
- Typical apex angle
- 120 or 90 degrees
- Example ground length savings
- A dipole for the 80 meter band requires about 140 feet (43 m) end to end; an inverted vee with a 40-foot (12 m) apex elevation requires only 115 feet (35 m) of ground length.
- Free space max gain dipole
- 2.15 dBi
- Free space max gain inverted vee
- 1.9 dBi
- Practical gain at 40 degrees takeoff ang
- 6 dBi toward sides, 1.2 dBi toward ends
Lore & Background
The inverted vee antenna is commonly used by amateur radio stations and can be used aboard sailing vessels requiring better HF performance than available with a short whip antenna. It requires only a single, tall support at the center, with the ends insulated and secured to anchors near ground level or near the roof if mounted on a house. This simplified arrangement has several advantages, including a shorter ground distance between the ends. For radio amateurs living on small parcels of property, such savings can make it possible to use the lower frequency amateur bands. In theory, the gain of an inverted vee is similar to that of a dipole at the same elevation because most of the radiation is from the high-current portion of the antenna, which is near the center. Since the center of both antennas are the same height, there is little difference in performance. Antenna modeling software bears this out for free-space models, predicting maximum gain of 2.15 dBi for the dipole and 1.9 dBi for the inverted vee.
Reader's Guide
In practice, ground proximity and ground conductivity as well as end effects reduce the efficiency of the inverted vee considerably compared to the dipole. In the example of a 40-foot apex elevation, considering a useful take-off angle of 40 degrees above the horizon, the inverted vee produces a maximum gain of 1 dBi in a circular pattern, whereas the dipole produces an oval pattern ranging from 6 dBi toward the sides down to 1.2 dBi toward the ends. Elevating the antennas higher above ground somewhat resolves the disparity, but considering the practical, legal and financial limits which influence most antenna installations, the inverted vee will be observably inferior in performance to a dipole by 2 to 4 dB. However, if space is limited, an inverted vee may permit operation on frequencies that would not be possible with a full-sized dipole. Its significance lies in enabling lower-frequency amateur band operation on small parcels of property where a full horizontal dipole would be impractical.
Did You Know?
- The inverted vee antenna is horizontally polarized and has a similar pattern compared to a traditional horizontal dipole.
- It requires only a single, tall support at the center, with ends secured near ground level or roof anchors.
- For the 80 meter band, an inverted vee with a 40-foot apex needs 115 feet of ground length versus 140 feet for a dipole.
- In free-space modeling, the inverted vee has a predicted maximum gain of 1.9 dBi, compared to 2.15 dBi for a dipole.
Design Philosophy & Radiation Performance
The Moxon rectangle represents a deliberate simplification of the Yagi-Uda antenna concept, stripping away all directors and retaining only a driven element and a single parasitic reflector. Named after amateur radio operator and handbook author Les Moxon (call sign G6XN), this two-element parasitic array uses folded dipole elements arranged in a rectangular geometry. The driven element occupies slightly less than half the rectangle's perimeter, while the reflector claims the remaining portion. Because of the folded ends, each element's physical length runs to roughly seventy percent of what an equivalent straight dipole would require. The result is a modest but useful directivity of approximately 2.0 dB, with a pronounced null at the rear that produces a front-to-back ratio reaching as high as 9.7 dBi on the 28 MHz band. Crucially, the antenna is single-frequency: the precise placement and sizing of the reflector are tightly coupled to wavelength, meaning each Moxon functions correctly only on the band for which it was specifically designed.
Construction Methods Across Frequency Bands
The Moxon's appeal to builders lies in its straightforward mechanical layout. The driven element on one side is cut slightly shorter than a half-wavelength, while the reflector on the opposite side is cut slightly longer. The two elements are joined at their ends by an insulator, creating a rigid rectangular frame. For shortwave applications, constructors commonly fashion the spreaders from bamboo or glass-fiber reinforced plastics, with the radiator and reflector formed from wire. This approach keeps wind loading minimal and the overall weight very low. At VHF and UHF frequencies, where the physical dimensions shrink considerably, builders more often turn to aluminum tubing in diameters ranging from roughly three-eighths to three-quarters of an inch. The thicker conductors take advantage of the broader resonant bandwidth available at those frequencies while still avoiding excessive wind load. The overall layout closely resembles the well-known VK2ABQ-square, giving experienced builders a familiar reference point when planning their construction.
The Amateur Radio Community's Embrace
Radio amateurs have embraced the Moxon rectangle as a go-to choice for portable operations, particularly during field day events and emergency communications deployments. The antenna's light weight combined with its rugged mechanical construction makes it ideally suited to situations where operators need reliable directional performance without the complexity of multi-element arrays. Les Moxon himself, identified by his call sign G6XN, was both an active amateur operator and a prolific author of antenna handbooks, lending the design a heritage rooted in practical field experience rather than purely theoretical work. The antenna's popularity is further sustained by the community's shared knowledge: Allen Baker published a detailed 6-meter Moxon build in QST Magazine in 2004, and the Lincoln, California-based John P. Labutski Memorial Amateur Radio Club has documented a Moxon project under the call sign KD6WD. These contributions reflect a culture where builders document, share, and refine designs for the collective benefit of the hobby.
Engineering Analysis & Design Tools
Behind the Moxon's seemingly simple geometry lies a body of careful engineering analysis. L.B. Cebik, known by his call sign W4RNL, undertook detailed comparisons and calculations across several different Moxon antenna versions, establishing empirical relationships that describe how element lengths, spacing, and folded-end geometry interact to produce the antenna's radiation characteristics. Building on Cebik's empirical formulas, Maguire (AC6LA) developed a calculator that allows operators to compute dimensions for their specific operating frequency. Additionally, Richard D. Alloway (N3WWN) created a web-browser-based Moxon calculator, making the design process accessible to anyone with internet access. These tools are particularly important because the Moxon is inherently a single-frequency device: the reflector's size and position are highly wavelength-dependent, so a generic or approximate build will not perform as intended. The availability of multiple independent calculators and published analyses gives builders confidence that their hand-built antenna will deliver the expected directivity and front-to-back performance on their chosen band.
Frequently Asked Questions
Who is the Inverted Vee Antenna?
The Inverted Vee is a dipole variant whose two radiating legs are bent downward from a single central apex, giving it the silhouette of an upside-down "V" when viewed from the side. The legs typically meet at a 90- or 120-degree angle at the top.
What are the Inverted Vee Antenna's powers and role?
Its signature ability is compressing a dipole's ground footprint with only a small penalty in radiated power, making it the go-to choice for operators with limited yard space. As a concrete example, an 80-meter dipole that would span roughly 140 feet horizontally shrinks to about 115 feet of ground length when the apex is raised to 40 feet.
Why is the Inverted Vee Antenna important to the ham radio community?
It lets operators in cramped urban or suburban lots deploy a resonant, omnidirectional antenna without needing a long horizontal wire run. At a practical 40-degree takeoff angle it still radiates about 6 dBi toward its broadside, keeping it competitive with a full-size dipole for most general-coverage work.
What is the Inverted Vee Antenna's known weakness?
Because the legs angle downward, the radiation pattern tilts and gain toward the ends drops to roughly 1.2 dBi at a 40-degree takeoff angle. It also demands a single tall support structure, which can be a real obstacle in areas with height restrictions or no suitable tree.
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