By: KA5WNX
End Fire Feed Vertical Antennas
Two Vertical Pair Antennas
1/2 wave
492/frequency
Antenna Seperation
Antenna Seperation
A bidirectional figure eight pattern is obtained when you use two vertical antennas that are separated by a half wave (492/frequency) and are feed out of phase. Whenever you use a 1/2 wave spacing, you will always need to use odd quarter wavelength coax line.
The closer you bring the antennas together, the larger and broader the coralloidal pattern. The further you space them, the sharper the pattern, thus a moderate amount of gain can be obtained.
Direction of Signal
I have discovered that at the lower bands that it does not matter how high off the ground these verticals are, just make sure that your feed line is long enough to reach the first antenna.
Formula for 1/2 Wave Vertical Element: 234/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.
Separation of antennas is: 492/frequency in MHz.
Separation of antennas is: 492/frequency in MHz.