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Tests done by J.S. Belrose (1994) [7] showed that though the conventional T²FD length is close to a full-size 80 meter (3.5–4.0 MHz) antenna, the antenna starts to suffer serious signal loss both on transmit and receive below 10 MHz (30 m), with the 80 meter band signals −10 dB down (90% power loss) from a reference dipole at 10 MHz. [7]
Simulating the end-fed half-wave (EFHW) dipole antenna; VK3IL - Multiband end-fed 80-10m antenna - NEC2 model file of a "MyAntennas EFHW-8010" multi-band antenna. Other retail books (such as The ARRL Antenna Book, Marcel De Canck's Advanced Antenna Modeling, and others) also include antenna model files.
German physicist Heinrich Hertz first demonstrated the existence of radio waves in 1887 using what we now know as a dipole antenna (with capacitative end-loading). On the other hand, Guglielmo Marconi empirically found that he could just ground the transmitter (or one side of a transmission line, if used) dispensing with one half of the antenna, thus realizing the vertical or monopole antenna.
The electric field strength at a specific point can be determined from the power delivered to the transmitting antenna, its geometry and radiation resistance. Consider the case of a center-fed half-wave dipole antenna in free space, where the total length L is equal to one half wavelength (λ/2). If constructed from thin conductors, the current ...
When the antenna is fed at a point of maximum current, as in the common center-fed half-wave dipole or base-fed quarter-wave monopole, that value is mostly the radiation resistance. However, if the antenna is fed at some other point, the equivalent radiation resistance at that point R r a d 1 {\displaystyle \ R_{\mathsf {rad\ 1}}\ } can easily ...
Typical antenna parameters are gain, bandwidth, radiation pattern, beamwidth, polarization, impedance; These are imperative communicative means. The antenna pattern is the response of the antenna to a plane wave incident from a given direction or the relative power density of the wave transmitted by the antenna in a given direction. For a ...