The Half Wave
The 1/2 Wave Vertical
Vertical Ground Plane Antenna
The Vertical 1/2 Wave Ground Plane antenna has a gain of 4.5dbi over isotropic source. The center conductor goes to vertical element and the outer conductor (braided wire) goes to the horizontal element.
The Vertical Ground Plane antenna impedance averages 85 ohms at the base, and can range from 36 ohms to 200 ohms depending upon the transmission line used. Separation of the center and outer conductor where the coax or other feedline connect should not extend beyond 1" inch.
Always mount the Vertical Ground Plane antenna at least it's total length, or greater height above the ground or building for best results.
Note: The 1/2 wave vertical ground plane antenna requires either a impedance matching stub or a SWR Match Box to bring the SWR ratio to below 1.5:1 or better. The natural state is over 85 ohms at the feed point.
The Vertical Ground Plane antenna impedance averages 85 ohms at the base, and can range from 36 ohms to 200 ohms depending upon the transmission line used. Separation of the center and outer conductor where the coax or other feedline connect should not extend beyond 1" inch.
Always mount the Vertical Ground Plane antenna at least it's total length, or greater height above the ground or building for best results.
Note: The 1/2 wave vertical ground plane antenna requires either a impedance matching stub or a SWR Match Box to bring the SWR ratio to below 1.5:1 or better. The natural state is over 85 ohms at the feed point.
Antenna Trans-match
A Base Tuner is often used to lower SWR's
Half wave vertical antennas and the alike can be fed with a inline balanced tuner to attain a more uniform radiation from the driven element.
The transmission line should be routed directly away from the antenna in order for this to be so for optimum communications results.
The transmission line should be routed directly away from the antenna in order for this to be so for optimum communications results.
Formula for 1/2 Wave Vertical Element: 468/frequency in MHz.
To get the inches instead of a decimal point, just subtract the feet, and multiply 12 times the decimal point left over.
Each leg of the ground plane elements is formulated by 234/frequency in MHz.