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Inverted Vee | |
11/09/06 |
 
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General Information The Inverted Vee Antenna is a 50 ohm (approximately) bi-directional antenna. The Inverted Vee is fabricated just like a Dipole, but is installed with the legs of the antenna pointing toward the ground. The angle between the two dipole legs is usually between 90 to 120 degrees, depending on the feed point height and leg length. The Inverted Vee has a very low take-off angle over a Dipole making it a better choice for long distance (DX) communications. Its 50 ohm impedance is desired because it matches that of RG-58 or RG-8 coax feed line and the normal input/output impedance of a receiver/transmitter or transceiver, thus allowing maximum power transfer to occur (minimum loss of signal).
Antenna Construction The Inverted Vee Antenna is made by attaching (i.e. soldering or other secure electrical connection) two (2) wires, equal in length, to the feed line as shown below.
Length of Inverted Vee Wire Antenna (B Length) The physical length of a resonant Inverted Vee antenna is shorter than a half wavelength in free space. Therefore, the physical length of a Inverted Vee must be made approximately 5% shorter than that value calculated from the free-space wavelength equation. A half wavelength antenna in free-space has the following length: λ (1/2 wavelength antenna in Feet) = 492 / Frequency (Mhz) A half wavelength (Length B) antenna with 5% reduction in length has the following length: λ (1/2 wavelength antenna in Feet) = 468 / Frequency (Mhz) Example: Calculation for a 20 meter or 14.200 Mhz (14,200,000 hertz) antenna is as follows: λ (1/2 wavelength antenna in Feet) = 468 / Frequency (Mhz) λ (1/2 wavelength antenna in Feet) = 468 / 14.2 λ (1/2 wavelength antenna in Feet) = 32.96' or 32' 11.5" (.96 x 12") So if B = 32.96', then A= 32.96' x 0.5 or 16.48'
Pre-Calculated Inverted Vee Wire Antenna Lengths Here are pre-calculated lengths for fabricating a half wave Inverted Vee antenna. Take the B Wire Length dimension and cut it in half creating two equal half lengths known as A.
Installing a Inverted Vee Antenna The Inverted Vee Antenna is a bi-directional antenna. This means you can receive or transmit a signal much stronger in two directions (both sides) and weaker off both ends as shown below. Therefore, you need to make sure the sides of the antenna are in the direction you want to receive/transmit the loudest.
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This site was last updated 08/27/06
