Calculation method of length of single whip antenna

Source: Length calculation method of single whip antenna

When doing radio frequency transmission, the choice and length of the antenna has a great influence on the reception sensitivity of the signal, the following is a brief overview of the antenna calculation:
Alternating currents in a piece of metal wire can be emitted to the space to alternately change the induced electric field and the induced magnetic field, which is the emission of radio signals. Conversely, alternating electromagnetic fields in space can sense alternating currents when confronted with metal conductors, which corresponds to the reception of wireless signals.
When transmitting and receiving on the radio, it is hoped that the alternating current in the wire can be converted into the electromagnetic wave in space effectively, or the electromagnetic wave in the space can be converted into the alternating current in the conductor most effectively. This is for the transmission and reception of the wire to obtain the best conversion efficiency requirements, to meet such requirements for the transmission and reception of wireless electromagnetic signals of the conductor called the antenna.
Theory and practice show that the length of the current line is 1/4 of the wavelength of the radio signal, and the transmitting and receiving conversion efficiency of the antenna is the highest. As a result, the length of the antenna will be determined by the frequency, or wavelength, of the signal being transmitted and received. As long as the corresponding transmitting and receiving center frequency can be calculated using the following formula to calculate the wavelength of the corresponding radio signal, and then the calculated wavelength divided by 4 is the corresponding optimal antenna length.
The conversion formula for frequency and wavelength is:
Wavelength = 300,000 km/frequency
= 300000000 m/frequency (the resulting unit is meters))
Example: To find the antenna length of amateur radio station
The known amateur radio station uses a signal frequency of 435MHz near the wavelength of:
Wavelength = 300000 km/435mhz
= 300000000/435000000
= 300/435
= 0.69 m
The corresponding optimal antenna length should be 0.69/4, equal to 0.1725 meters
When the frequency is 439MH, you can simplify the calculation formula to
Wavelength =300/439
= 0.683 m
The best antenna length is 0.683 m/4, equal to 0.17 m
Note: As long as there is alternating current in the metal body, the metal body will radiate electromagnetic waves to space, conversely, as long as there is a certain intensity in the space electromagnetic signal, will be in the space of the metal body on the induction of alternating current. The difference between an antenna and a general metal body is that the antenna emphasizes the most effective conversion of alternating currents in the metal into space electromagnetic waves or the most effective conversion of space electromagnetic waves into a metal body alternating current signals.

Length calculation method of single whip antenna (RPM)