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What Is a Bowtie Antenna?

Tamara Wilhite is a technical writer, industrial engineer, mother of two, and published sci-fi and horror author.

What Is a Bowtie Antenna?

A bowtie antenna uses triangular elements instead of straight rods as the antenna elements. The triangular elements sticking out on both sides of the antenna resemble a bow tie, hence the name.

The “wings” of the antenna flare out symmetrically on both sides of the supporting beam. The two antennas nearly touch at the center. A bowtie antenna is sometimes called a butterfly antenna, because it looks like a butterfly with its wings held open. When the bow tie elements have a metal bar that closes the antenna, it may be called a cat’s whisker antenna.

The bowtie antenna is a type of UHF fan dipole antenna. Bow tie antennas may resemble log periodic antennas, but they are not considered LP antennas. Some people do consider the bow tie antenna a simpler version of the log periodic tooth antenna.

A log periodic antenna

A log periodic antenna

Is a Bowtie Antenna a Biconical Antenna?

A bowtie antenna is a type of biconical antenna. The bowtie antenna is considered a two dimensional version of the true biconical antenna. A true biconical antenna has several elements sticking out in a 360 degree pattern in both directions.

What Are the Advantages of Bowtie Antennas?

The bandwidth of the antenna is increased by using triangular elements over straight ones. Furthermore, the antennas often receive signals from a 60 degree angle, perfect for receiving signals from various sources. This is why bowtie antennas were common used with televisions receiving over the air broadcasts. They could receive a wide range of UHF signals, and it will do much better than a thin wire dipole antenna in this regard.

This type of antenna is lighter in weight than a fan dipole antenna that connects the horizontal elements. The design also makes it more wind resistant. That’s a plus when you don’t want to have to climb on the roof to restore the antenna so you can watch the news. The design is made stronger by the metal bar that closes the bow tie, though that does add to its weight.

This antenna design is cheap and easy to construct. That’s why rabbit ear antennas were so common on old televisions.

The mesh reflector in the bowtie antenna is more efficient than other types of antennas such as yagi antennas.

A yagi antenna

A yagi antenna

What Are the Disadvantages of Bowtie Antennas?

Biconical antennas, including bowtie antennas, have poor transmitting efficiencies in the low end of their frequency range. A log periodic antenna is better in that regard.

A bowtie antenna isn’t as well suited as a full biconical antenna in RF sniffing or RF signal detection.

Observations about Bowtie Antennas

A bow tie antenna has a vertical polarization. It will receive signals in the direction the “cone” or wings of the butterfly are pointed. It won’t receive signals outside of that plane, though that ceases to matter when you’re pointing the antenna at a TV or radio tower on the horizon.

You can put a reflector or dish behind a bow tie antenna, but this isn’t always necessary.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: Is there an equation that calculates the dimension of patch bowtie antenna?

Answer: Patch or Bowtie antenna? These are different types of antennas, each with their own equations.

I have seen an equation for developing a patch, and it is LONG! 8 main factors I can think of off the top of my head.

If I had to do such design work, I'd use RF design software.

© 2019 Tamara Wilhite

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