Читать книгу Antenna and EM Modeling with MATLAB Antenna Toolbox - Sergey N. Makarov - Страница 25

We will show later in the text that all metal antennas could be scaled in size so that a dipole with the size twice as small as the original one has the resonant frequency that is two times larger than the original resonant frequency. Similarly, a dipole with the size twice as large as the original one has the resonant frequency that is two times less. In other words, small antennas have high resonant frequencies and vice versa.

The scaling property of the antenna implies measuring its length l_A in terms of a dimensionless quantity called electrical length. The electrical length is simply the product of l_A and the wavenumber k = 2π/λ. The electrical length of the antenna does not depend on its operation frequency. A dipole antenna resonating at 100 MHz or at 5 GHz has the same electrical length.