Beverage antennas - One wire configuration info
- Use separate ground rods, as sharing can cause signal coupling through the connection.
- Keep the Beverage ends away from towers that can re-radiate signals, even if they are not used as transmit verticals.
- Woods, trees, and vegetation, represent only minimal signal loss reported over many years. One wooded area, low to the ground Beverage at my QTH is also under the snow much of the winter, and works fine.
- Maintain a reasonable constant height above ground except at the ends that may be tapered to ground level.
Follow the general contour of the earth, but not every small dip or bump.
- Beverage antennas "want to work". For best results run a straight line. If a straight run can not be maintained, good results can be obtained with less than perfect runs.
- If the Beverage is being used as a single direction terminated antenna, the termination resistance
is controlled more by ground conductivity, than wire height. A poor conductivity earth termination would typically
be 350 ohms or lower. A more conductive earth termination would typically be 450 ohms or higher.
- When choosing a termination resistance, avoid the one that gives the minimum VSWR on the
band of interest, rather choose the resistance that gives the lowest VSWR over a wide frequency range with a slow
increase at the highest frequency end. You may end up with a 1.8:1 VSWR, but you will have found the
characteristic impedance of the wire resulting in the best antenna front to back ratio. (The 1.8:1 VSWR would be most likely from a matching transformer to antenna impedance difference)
- Beverage antennas require the bending of radio waves to work. Lower frequency radio waves bend around mountains, into valleys, and have deeper earth penetration. Poor conductivity earth helps provide earth penetration, and the necessary bending. (Often called tilt angle)
- It has been said "A Beverage antenna should be run across a desert with a swamp at each end" A Beverage will not work well over highly conductive ground or sea water. (The swamp at each end was for your ground rod.)
- If you are near the sea, running the Beverage antenna along the beach will result in a antenna that will not work well. You could arrange your Beverage so it starts or ends up near the waters edge to get a good ground, and run away from the coast line at 90 degrees, to receive those low angle signals that tend to follow sea water. For other directions avoid the ocean's edge.
- If sea water extends under the earths surface inland, treat this as a high conductive area.
- When purchasing a Beverage antenna transformer, Recommend a 450 ohm transformer for a more conductive locations, and a 330/350 ohm transformer for a low conductivity locations. Closer matching to the transformer will increase the signal to your radio, but will not change the antenna pattern.
- Beverage antennas are low impedance, low Q devices, and do not couple well. Beverage runs can cross each other if a few feet of clearance is allowed.
- Radial fields radiate energy from the connected vertical. Avoid running a receive antenna, or receive coax across one. (Raised radials radiate more signal energy than in ground radials.)
- Take care not to transmit into a Beverage antenna with standard transformers. If transmit is desired, an
antenna tuner could be used in place of the Beverage transformer. A much higher wattage termination resistor would be needed.
(Beverage antennas have negative gains)
- For those not wanting to go in to a switchable Beverage system. It is possible to recieve in the direction that wires can not be run. A KB-2 transformer can be connected to two wires running away from the direction wanted will provide that reverse directivity. (Two wires not terminated at the far end, a ground rod at the KB-2 box, a termination resistor on the forward SO-239 connector, and a coax from the reverse SO-239 KB-2 connector to your radio shack is all that is needed). This method is not new. Harold Beverage used it at 1XAO the Belfast, Maine long wave, radio relay station in 1923.
- There have problems reported using heat shrink on termination resistors, and multiple reports saying no protective covering is necessary.
Two wire, two direction Beverage notes
- When using individual wires, maintain the spacing between the two wires. This will help the front to side signal ratio to be near optimum. Treating the wire spacing like a transmission line will help the forward and reverse signal levels to be more equal with proper transformers.
- Slope the wires down to ground at both ends. This idea is not original. I read it in one of the early "Low
Band DXing" books by ON4UN. Over a number of years I tried this at my
locations, and at a friends QTH. We found the slope did not change low angle vertical signals compared to a straight drop. We did find that high angle signals were reduced, with longer 3/8 wave slopes.
- In Northern climates, use a long ground rod as winter time frozen earth does not conduct well.
If it is not possible to drive a rod all the way in, avoid leaving a large amount above the ground. (Length may increase pick up of nearby strong AM radio station signals) Mixing, birdies are possible. (But also, cut the excess off for human safety)
- The coax outer shield can pick up signals and compromise the front to back. It is good to have
the last 60 or more feet of coax buried near the KB-2 box.
This avoids pick up and the capacitance to ground will have a beneficial effect.
Coax laying on the ground is usually OK. In cases where the coax is above ground, an effort should be taken to remove common mode signal pick up.
- Termination of un-used coax is not necessary with accurately placed transformer coil center taps.
The two wire Beverage system is a RF version of the old telephone simplex circuit of the 1930's. (Two talk circuits could take place on the same wire pair with electrically center tapped transformers at each end, without cross talk.)
- Standard published wire lengths for a Beverage from "on line" tables available are 290, 440, 600, 800 feet.
- Covered wire results in a slowing of radio waves known as velocity factor. A given covered wire length will resonate lower in frequency than uncovered wire.
- Many find 9 feet above the ground is a good compromise height. (Crossing a roadway not included)
- I have a close to the ground Beverage antenna in an out of the way area. The pattern and signal to noise ratio are excellent. Roundup was used to remove vegetation from the Beverage run with good results. Deer collisions ceased to be a problem.
QRN sometimes noted in solar storms is often less than with other taller Beverage antennas. At 2 feet above ground found a pre-amplifier to be unnecessary
- Much of the expense of a two wire Beverage is the cost of the wire, and upkeep. 450 ohm cable expense is high,
and breakage repair is difficult. WD-1 wire is inexpensive, but repair is somewhat difficult.(Steel strands send me looking for band aids) Both types can deteriorate if water penetrates the insulation. Galvanized electric fence wire spaced about 6-8 inches has an impedance about 600 ohms (depending upon wire size), and is available for about $22.00 for 1/4 mile at farm supply stores. A Western Union splice works well in case of breakage.
- In the past, I have tried 680 ohm two wire Beverage antennas using electric fence wire spaced horizontally, then vertically. No reception difference noted. I found vertical runs much easier with out
the need of cross arms.
BOG antenna notes
- The most improvement in signal strength comes from the first inch above ground. This can occur naturally from leaf cover,
and low vegetation. 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 250 and 350 ohms (300 ohms is typical).
- Termination testing: Use changes of 50 ohms to get close, then 25 ohms. Less than 25 ohm differences are difficult to detect.
- Longer BOG antennas may loose signal strength. One that works well on 160 meters, may be lower signal strength on 80 meters and possibly reverse direction on 40 meters.(This has to do with self termination that vary with soil conditions)
- Updated: The 160 foot BOG is not as efficient as the 440 foot up in the air Beverage, but works well on 160,80, and 40 meters, is more directional than expected, and somewhat out of sight. Information given may give a starting point for others.
- Installed a 50 to 50 ohm isolation transformer in the BOG antenna coax cable at the shack end. This solved TV and house noise picked up by the coax.(Reduction of Common mode pick up)
- A BOG antenna will self terminate beyond a length for a given frequency. This length is determined by the close proximity of your type of soil.
An easy way to find your best, single wire, length for 160 meters is to lay out about 200 feet of insulated wire in the desired direction. Connect the near end of the wire to a 350 ohm matching transformer that also has a connection to a long ground rod. For this test, leave the far wire end un-terminated. Connect your VSWR analyzer to the matching transformer and sweep through frequencies 1.8 MHZ and above. Above a given frequency the VSWR will go to a low value and stay there as you continue. This low value is self termination that may cause reverse direction and an unpredictable pattern.
Shorten the wire far end until the band or bands of interest are not self terminating. Then drive a long ground rod, and terminate with a 300 +/- ohm non-inductive resistor.
Beverage antennas with 1/4 wave radial grounds become optimum for one band per "Low Band DXng". A BOG antenna is no exception.
Shorter radials may pick up noise or signals that have incomplete cancellation in the termination resistor.
Use long, minimum impedance, ground rods for best wide band results.
Long BOG research notes:
(One wavelength for 160 meters in free space is 537.4 feet, times the mid coast Maine .4614 velocity factor for field telephone wire on the ground equals 247.9 feet). On going research of a 247 foot, two wire, two direction BOG has ended.
Earth freezing caused pattern changes, but found it useable for many DX contacts.
BOG Transformers are available in KB-1, KB-2 and KB-3 versions.
Pennant, Flag, Delta antenna notes
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K1FZ (Bruce Clark) Background highlights:
Worked in the late 1950's to early 1970's for WLBZ-TV Bangor, Maine as a transmitter engineer.
Most exciting employment: Worked as the senior maintenance engineer for the Christian Science Monitor syndicate short wave AM radio station in Maine. Transmitter power output was 500 KW. Two high gain TCI model 611 4X4 slewable curtain arrays, topping 363 feet AGL, gave a ERP power of 5 megawatts. (ERP Varied with frequency in use)
Presently semi retired and working as the Contract Engineer for WERU-FM, a PBS, Community Radio FM broadcast station. Music, programs vary with day, and time of day. Check the program schedule for your favoite kind of music, and listen on line.
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