Wire on ground antenna
Single BOG "Wire on ground antenna"
- The most improvement in signal strength comes from the first inch above ground. How ever the best antenna pattern occurs with the BOG wire against ground. Covered (insulated) wires are necessary.
- Impedance of the termination will vary with ground conductivity, wire size, and height above ground. Recent reported termination impedances have been between 200 and 250 ohms.
- Termination testing: Use changes of 25 ohms. Less than 25 ohm differences are difficult to detect.
- The 200 foot BOG is not as efficient as the 440 foot up in the air Beverage, but works well, is more directional than expected, and mostly out of sight.
- Recent research has found that although a BOG antenna can be used over two, sometimes three bands, Excellent results occur over a very narrow band of frequencies. The best pattern comes with the best front to back, over typical earth between 180 to 200 feet.
Find the frequency of maximum front to back, and adjust the BOG wire length to 160 meters.
- Because the wire on ground is "trying" to develop signal voltage between the wire and the earth it sits upon, A good ground connection is best. In areas where the earth freezes 3 to 4 feet or in very dry soil, long ground rods make the difference
- For best signal strength recovery use long, multiple, minimum impedance, ground rods.
- A preamplifier in the radio room may be necessary to increase signal gain.
- In the event ground rods cannot be used for 160 meters, use two 65 foot buried, or on ground radials at each end, connected at right angles to the BOG wire. Looking down the BOG wire forming a I. This configuration will give minimum unwanted signal/noise pickup from the radials.
- Shorter, unbalanced radials may pick up noise or signals that have less cancellation at a transformer ground connection.
Common mode pick up:
- Remove the coax from the BOG transformer and listen on the receiver to check possible coax cable pickup problems.
- A 50 to 50 ohm isolation transformer in the BOG antenna coax cable at the shack end solved slight TV and house noise pick up.
- Coax cable could have been buried 5-6 inches deep to reduce pick up.
- A ferrite wound coil, or common mode choke could been placed at the receiver end of the coax.
- Now a popular choke is constructed by winding 6-8 turns of small diameter coax in a 6 inch diameter coil and held together with plastic ties. One mix 31 ferrite 'clamp on' core Amidon 2x31-1081P2, or equivalent is installed over the windings.
Beverage antenna; notes
- Two wire, two direction BOG's check IV2PRK listings.
Luis, IV3PRK, BOG antenna research start at HC1PF
Luis, IV3PRK BOG antenna modeling at HC1PF