Batwing antenna
First widely used TV broadcasting antenna with wide bandwidth.
The batwing antenna, also called the super turnstile, is a type of broadcasting antenna that operates at VHF and UHF frequencies. Its name comes from its shape, which looks like a bat’s wing or a bow tie. This design was the first to be widely used for television broadcasting, valued for its broad bandwidth and horizontally polarized signal.
In terms of design, the batwing is a specialized crossed dipole antenna, a variation of the turnstile type. Two pairs of identical vertical elements, shaped like bat wings, are mounted at right angles around a central mast. The “wings” on opposite sides form a dipole. To achieve an omnidirectional pattern, the two dipoles are fed with a 90-degree phase shift. The antenna radiates horizontally polarized waves in the horizontal plane. Each set of four elements at one height is called a bay. The radiation pattern is nearly omnidirectional but has four small lobes, or maxima, pointing in the directions of the four elements.
To reduce power sent in unwanted vertical directions, broadcast applications stack multiple bays vertically, spaced about one wavelength apart and fed in phase. This creates a collinear array that produces an omnidirectional pattern with higher horizontal gain—more energy goes sideways, less goes up or down—making it suitable for terrestrial broadcasting. The batwing shape itself comes from the butterfly antenna, a flattened biconical design. This shape gives the antenna a wide bandwidth, roughly 20% of the operating frequency at a VSWR of 1.1:1. That wide bandwidth allowed broadcasters to use a single antenna for multiple television signals, which made the batwing the preferred choice for low-band TV stations (Band I, channels 2–6) in early broadcast television.
- Bandwidth
- approximately 20% of operating frequency at a VSWR of 1.1:1
- Polarization
- horizontal
- Radiation pattern
- omnidirectional with four small lobes
- Element shape
- batwing or bow tie
- Antenna type
- crossed dipole antenna, variant of turnstile antenna
Lore & Background
The batwing antenna is a specialized type of crossed dipole antenna, a variant of the turnstile antenna. Two pairs of identical vertical batwing-shaped elements are mounted at right angles around a common mast. Element “wings” on opposite sides are fed as a dipole. To generate an omnidirectional pattern, the two dipoles are fed 90° out of phase. The antenna radiates horizontally polarized radiation in the horizontal plane. Each group of four elements at a single level is referred to as a bay. The radiation pattern is close to omnidirectional but has four small lobes (maxima) in the directions of the four elements.
To reduce power radiated in the unwanted axial directions, in broadcast applications multiple bays fed in phase are stacked vertically with a spacing of approximately one wavelength, to create a collinear array. This generates an omnidirectional radiation pattern with increased horizontal gain, suitable for terrestrial broadcasting. The "batwing" shape of the elements is adapted from the butterfly antenna (a flattened biconical antenna), used because it gives the antenna a wide bandwidth of approximately 20% of operating frequency at a VSWR of 1.1:1. This made the batwing the preferred antenna for lowband TV stations (Band I; channels 2–6) in the early days of broadcast television.
Reader's Guide
The batwing antenna's significance lies in its role as the first widely used television broadcasting antenna, enabling the early expansion of TV broadcasting. Its wide bandwidth, approximately 20% of operating frequency at a VSWR of 1.1:1, allowed broadcasters to use a single antenna to transmit multiple television signals, a critical advantage in the early days of television. The design's horizontally polarized omnidirectional pattern, achieved through a crossed dipole arrangement with elements fed 90° out of phase, made it suitable for terrestrial broadcasting. Stacking multiple bays vertically in a collinear array further enhanced horizontal gain, directing more energy toward the horizon and reducing waste toward the sky or ground. The batwing's adaptation from the butterfly antenna (a flattened biconical antenna) provided the necessary wide bandwidth, making it the preferred choice for lowband TV stations (Band I; channels 2–6). Its legacy endures as a foundational antenna type for VHF and UHF broadcasting, particularly in television, where its characteristics addressed the practical needs of early broadcasters.
Did You Know?
- The batwing antenna is also called a super turnstile antenna.
- Multiple bays stacked vertically create a collinear array with increased horizontal gain.
Frequently Asked Questions
What is a Batwing antenna?
The Batwing antenna is a VHF/UHF broadcasting antenna whose elements are shaped like a bat's wings or a bow tie. It is a specialized crossed dipole design that falls under the broader turnstile antenna family.
What does a Batwing antenna actually look like?
Two pairs of identical vertical, bat-wing-shaped elements are mounted at right angles around a central mast, with the wings on opposite sides forming the signature cross silhouette. This geometry is what gives the design its name.
Why was the Batwing antenna a big deal for early television?
It was the first antenna type widely deployed for TV broadcasting because it offered a broad bandwidth and a horizontally polarized signal out of the box. That combination made it a practical, off-the-shelf solution for stations that needed dependable coverage.
What are the Batwing antenna's key electrical specs?
It radiates an omnidirectional pattern with four small lobes and produces a horizontally polarized signal. Bandwidth covers roughly 20 percent of the operating frequency at a VSWR of 1.1 to 1.
How is a Batwing antenna different from a regular turnstile antenna?
While both are crossed-dipole structures, the Batwing swaps the plain dipole arms for the distinctive bat-wing or bow-tie element shape. That tailored geometry is what delivers the wide bandwidth that made it the go-to choice for early TV transmitters.
More in Antenna Types 1-24
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