Bow Tie Antenna Calculator
Calculate wavelength, element length and recommended feed dimensions for a bow-tie antenna.
2
Inputs
Live
Math
3
Related
Enter parameters and click Calculate to view results
Formula & Theory
λ = 300/f, Total Length ≈ 0.48λ, Feed Gap ≈ 1-3% of λThis formula is used to calculate antenna parameters for bow tie antenna calculator.
Overview
The Bow Tie Antenna Calculator determines total tip-to-tip length, individual triangular element dimensions, feed gap spacing, and operating wavelength for planar bow-tie dipoles. Widely used in UHF TV reception, Ground Penetrating Radar (GPR), and wideband wireless communications, bow-tie antennas offer significantly broader bandwidth than standard thin-wire dipoles.
Input Guide
Enter Center Frequency, Flare Angle exactly in the units shown by this bow tie antenna. Check the operating band, unit prefix, and decimal position before calculating; these are the inputs used by the formula.
- Center Frequency — use MHz.
- Flare Angle — use °.
Output Guide
The results describe the calculated bow tie antenna values for the inputs you entered. Check each value against the available space, selected components, feed system, and operating conditions before making a final design decision.
How This Calculator Works
The Bow Tie Antenna uses λ = 300/f, Total Length ≈ 0.48λ, Feed Gap ≈ 1-3% of λ. Supply Center Frequency (MHz), Flare Angle (°) in the displayed units, then use the calculated values as the first engineering target for this resonant antennas design or analysis.
Design Notes
A bow-tie antenna is a two-dimensional, planar variant of a biconical antenna. Flaring the dipole wire into triangular triangular sheets lowers the antenna Quality Factor ($Q$) and expands its operational bandwidth. The total tip-to-tip physical length is typically cut to approximately $0.48\lambda$ to compensate for end-effect capacitive loading. Flare angles between $60^{\circ}$ and $90^{\circ}$ provide a stable characteristic impedance ranging from $200\;\Omega$ to $300\;\Omega$ across a wide frequency range.
Build and Tuning Notes
When connecting a $50\;\Omega$ or $75\;\Omega$ coaxial feedline to a bow-tie antenna, install a matching transformer—typically a $4:1$ Guanella or Ruthroff balun—to eliminate common-mode currents and ensure proper impedance transformation. Maintain a tight feed gap ($1\%\text{ to }3\%$ of $\lambda$) to minimize parasitic lead inductance. Solid metal sheet elements can also be constructed using wire frames or mesh grids to reduce wind loading for outdoor installations.
Frequently Asked Questions
Why does a Bow-Tie Antenna offer wider bandwidth than a conventional dipole?
Flaring the antenna arms into triangular shapes creates a gradual impedance transition along the element length, lowering the radiation Quality Factor ($Q$) and allowing the antenna to maintain a low VSWR across a broad frequency band.
How does the Flare Angle affect antenna performance?
Increasing the flare angle (typically between $60^{\circ}$ and $90^{\circ}$) broadens the impedance bandwidth and lowers input resistance toward $200\text{--}300\;\Omega$. Narrower flare angles behave more like standard thin-wire dipoles with higher $Q$ and narrower bandwidths.
What balun ratio is required for a Bow-Tie Antenna?
Because the characteristic input impedance of a bow-tie antenna typically falls between $200\;\Omega$ and $300\;\Omega$, a $4:1$ balun is recommended when feeding the antenna with standard $50\;\Omega$ or $75\;\Omega$ coaxial cable.
Can wire mesh or metal frames replace solid sheet metal?
Yes. Wire mesh or skeletal triangular frames with perimeter conductors perform virtually identically to solid sheet metal elements at RF frequencies, while dramatically reducing weight and wind resistance.
Alex Warren
B.Sc. in Electrical & Electronic Engineering (EEE)
Alex specialises in antenna design and wave propagation. His expertise helps ensure these calculators present practical RF concepts, useful design estimates, and clear engineering guidance for students, HAM operators, and wireless professionals.