Quarter wave calculator. 3 meters. As the name suggests, the length of this transmission line if fixed at a quarter of the wavelength (λ/4). 11. Antenna Length Calculator Reviewed by: JJ Ben-Joseph Resonant antenna formulas In free space, wavelength is the ratio of the speed of light to the operating frequency: λ = c f For practical antennas, builders often need quarter-wave or half-wave segments. This calculator gives the lengths of the radiating element of a quarter wave (λ/4) ground plane monopole and the radials. What is a Quarter Wavelength Calculator? Definition: This calculator determines the quarter wavelength of a wave based on its frequency and propagation speed. This calculator can be used to design a Quarter Wave Ground Plane antenna, with radials. On-line antenna designer. Learn how to improve the efficiency and bandwidth of your antenna with radial wires and conductive ground plane. The calculator ensures a matching impedance of 50 Ohm without the need for additional components. b) Consider the three lossless lines is shown in Fig. Definition: This calculator determines the quarter wavelength of a wave based on its frequency and propagation speed. Enter the required frequency in MHz and the antenna designer will calculate the dimensions of the elements as shown below. Calculate the approximate length of a quarter-wave vertical antenna in feet and meters for any frequency in megahertz. Background A quarter-wave antenna, often used as a monopole antenna is mounted vertically and operates effectively over a ground plane. It works by transforming one impedance into another through a section exactly ¼ wavelength long (electrically). 1. Applying a velocity factor v_f that captures dielectric loading leads to L = v_f λ n where n equals 4 for quarter-wave monopoles and 2 . This assumes a velocity factor of 0. If Z 0= 50Ω, calculate: [4] [CO4, Analyzing] i) Zin looking in to line 1 ii) Zin looking into line 2 iii) Zin This calculator assumes propagation in a free space, earth atmosphere environment. This calculator can also solve for any one of the variables when the other two are known. Our sound wave calculator lets you calculate the wavelength of a sound wave if you know its frequency and speed (or the medium in which it's propagating). The page is useful for amateur radio operators looking to build Use our simple calculator to determine approximate dimensions of materials needed to build a vertical antenna. 6 meters. (ii) If the quarter-wave section is a two-wire line with D = 2. How Does the Calculator Work? The calculator uses the formula: Quarter Wave Antenna dimension calculator Back to Antenna calculator overview. Ahh, the good old quarter wave ground plane! This calculator can be used to design a Quarter Wave Ground Plane antenna, with radials. The length of radials, assuming a 10% increase, is 3. 66. The radiating element is a quarter wave (λ/4) and the radials are 12% longer. Calculate the required dimensions for a quarter wave antenna construction for any given frequency. A **quarter-wave transformer** is a segment of transmission line used to match two different impedances. 5 cm, and the wires are embedded in polystyrene with ϵr = 2. There are usually four radials, three being a minimum, but you could use up to six. The radials in such an antenna Waves are everywhere, and as sound is a mechanical wave present in many essential aspects of our lives, we created the sound wavelength calculator. Purpose: Essential for antenna design, acoustics, and RF engineering where quarter-wave elements are commonly used. The quarter wave coaxial impedance transformer is used to match an input and an output impedance at a given frequency for maximum power transfer. This is a true unbalanced antenna, with a feed impedance of around 50Ω and therefore a great This calculator is designed to give the vertical length (height) of a quarter wave ground plane antenna, and the length of each of the four radials Feb 21, 2026 · This page offers an online tool to calculate the dimensions for a quarter wave antenna based on a specified frequency. Quarter Wave Transformer Impedance Calculator A quarter wave transformer is used to match two transmission lines with different impedances. Choose from quarter-wave, half-wave, the powerful 5/8-wave, 3/4-wave, or full-wave, and calculate minimum lengths of required radials, and then shop for your needs on our other pages and select from our inventory of aluminum, fiberglass, wire, coax, connectors, and other parts and Oct 16, 2024 · Example Calculations A quarter wave (λ/4) antenna designed for 20 meter applications (15 MHz) has a length of 3. 2. It helps hams design antennas for optimal reception and transmission properties, using 1/4 wavelength elements. Full wave, half wave, and quarter wave antenna structures can be selected. Dec 30, 2025 · Enter the wave speed (propagation speed in the medium/structure) and frequency into the calculator to determine the quarter-wave resonator length. 6, determine the physical length of the quarter-wave section and the radius of the two wire conductors. Dec 22, 2024 · Velocity factors for different cables are provided here.