Organize and Share your Electronics the way you want. Sign-Up for a free account now. It takes only 30 seconds!

# The Half Wave Dipole or Hertz Antenna

The dipole antenna dates back to the early RF experiments of Heinrich Hertz in the late 19th century. It consists of a conductor that is broken in the center so that RF power can be applied to it. One can think of the half wave dipole as an open circuited transmission line that has been spread out, so that the transmission line can radiate a signal into space.
A dipole can be any length, but it most commonly is just under 1/2 wavelength long. A dipole with this length, known as a resonant or half wave dipole, has an input impedance that is purely resistive and lies between 30 and 80 ohms, which provides a good match to commercially available 50 ohms coaxial cables as well as commercial transmitters and receivers, most of which have 50 ohm output and input impedances. The length of a dipole can be approximately determined from the following formula:

l = 468/f

where:
l is the length in feet and
f is the frequency in MHz

The input impedance of a dipole antenna also depends on its electrical length. When the antenna is approximately an odd multiple of a half wavelength long, the input impedance is resistive and lies between 50 and 200 ohms. For antennas that are an even number of half wavelengths long, the input impedance is resistive and extremely high, between 1000 and 50,000 ohms.

Visit Here for more.

Gesture Controlled Smart Home
Design for a Wideband, Differential Transimpedance DAC Output
Wrist thrusters let you fly through the water effortlessly
Bertan/Spellman 225-20R HV power supply teardown
Adjusting clock with alarm, hygrometer & thermometer on 1.8″ ST7735 display
Adding an “extra sense” with rangefinders
This wireless game controller looks like a rug
How to run your ESP8266 for years on a battery
Calibration of a 3-Phase Energy Meter Board on the ADE7754
Making beats on a tiny Arduino DJ controller
Qinsi-QS5100 Sn63Pb37 solder profile
Water Detection System
Professional Hi-Fi 15W Tube Amplifier circuit
This Arduino machine will judge how sick your ollies are
Turn an old payphone into a boombox for ’90s hits
Big F’n 3D printer build
Temperature alarm for boiling milk
QuadBot is a 3D-printable walking robot for everyone
MicroConverter I2C Compatible Interface

Top