The ideal antenna length is typically a fraction of the signal's wavelength (λ), most commonly 1/4 wavelength (λ/4) for simple monopoles (like car antennas) or 1/2 wavelength (λ/2) for dipoles, allowing resonance for best performance, calculated by dividing the speed of light (300,000,000 m/s) by the frequency in Hertz (Hz) to find λ, then dividing by 2 or 4. For feet, use the formula 234 / frequency (MHz) for a quarter-wave, accounting for physical factors like velocity factor.
Ideally an antenna should be as long as half a wavelength of the signal you want to receive. Light travels 3 × 108 meters per second, so one wavelength of a 1 MHz signal is 300 m.
The effective length determines the voltage induced on the antenna by an incoming wave. - Equivalent areas include the effective area, scattering area, loss area, and capture area. These describe the power captured, scattered, dissipated, and delivered by the antenna when exposed to electromagnetic waves.
A rule of thumb is that for optimal transmission the antenna should be half the wavelength of the frequency (λ/2), and at the feed point this length should be divided by 2 so each side should measure (λ/4).
So the answer is yes, size does matter, but bigger isn't always better. It all depends on what your transmitting and receiving frequencies are. Theoretically, a longer antenna will have a greater range, but it is far more important for optimal radio performance that the length of the antenna matches the frequency.
10 ways to improve OTA antenna reception
Full-wave 20 meter dipole antenna measuring approximately 66 feet, 10.28 inches (66' 10.28"), split as approximately 33 feet, 5.14 inches (33' 5.14”) on each side.
The Antenna Equation
To calculate the range of an antenna, you multiply the square root of the antenna's height above water (in feet) by 1.42. The product will equal the antenna's communication range in miles.
The length of the antenna is determined by how high the frequency is compared to the wavelength. There's an inversely proportional relationship to the frequency and a directly proportional relationship to the wavelength which determines effective length.
Operating at 156-162MHz, maritime VHF bands have a wavelength between 1.72m and 1.92m (the distance between peaks). There is a relationship between this wavelength and the antenna length, which means that VHF aerials range from about 25cm up to 5-6m.
To convert your 40m vertical to run on say 80m or 75m, you just need to add a loading coil. The only problem will be that your SWR curve will be very narrow, so pick exactly where you want to tune the coil, or take a number of taps off the coil so that you can run say 3.79 for DX and 3.580 for digital (for instance).
As with a transmission line, an antenna's electrical length is increased by anything that adds shunt capacitance or series inductance to it, such as the presence of high permittivity dielectric material around it.
A standard recommendation for the 40m band (see QST, March 1936, p. 32, "An Unorthodox Antenna") is an 84' long end fed and a 17' long counterpoise (6.5' for 20m).
An ideal antenna for amateur radio is a theoretical construct that has perfect characteristics such as no losses, 100% efficiency in converting electrical energy into electromagnetic waves and vice versa, and completely uniform radiation in the desired direction.
The ideal length for the active element of a 2.4GHz antenna is 31.23mm. (To find this, you can search in Google: “c / 2.4GHz / 4”). The length of the active element of a monopole antenna is determined by the wavelength of the radio wave.
With this very high gain, the signal can receive from a very long distance but at a very narrow path. It will miss hotspots within a few miles and is designed to connect remote miners and other IoT devices to the Helium network from an exceptionally long distance of 10 miles over open terrain, or more.
distance = speed × time.
Unity gain (2.1 dBi) is a way of describing an antenna that outputs a signal at the same level at which it is input. The broad radiation pattern of unity gain antennas is less likely to be obstructed by buildings, bushland and hilly terrain.
Half-wave 60 meter dipole antenna with internal 1:1 choke balun. It measures approximately 87 feet, 9.56 inches (87' 9.56"), split as 43 feet, 10.78 inches (43' 10.78") on each side.
From all of these plots it was Page 2 obvious that an antenna height of 1.5 wavelengths best covered the 3 to 17 degree elevation angle range. On 10-Meters, this would be a height of about 50 feet.
Full-wave 11 meter band (CB Radio Band) dipole antenna measuring approximately 34 feet, 8.4 inches (34', 8.4") in total length, which comes to about 17 feet, 4.2 inches (17' 4.2”) on each side.
How can antenna faults be resolved?
Based on dozens of CNET's tests, the best indoor antenna is the Mohu Leaf, with great performance and an affordable price. You could also choose the previous winner, the Channel Master Flatenna. Both antennas provide excellent reception, simple installation and an affordable price.
Ensure proper polarization alignment (cross-pol <−20dB) and avoid obstructions in the Far-Field (>2D²/λ).