Beverage antenna - Beverage receiving antennas
One wire configuration notes
- Best to use separate ground rods, as sharing can cause signal coupling through the connection.
- Copper coating on steel ground rods disappears with time. Recommend the use of thick wall copper pipe, available in most hardware stores.
- Break away ties/fastenings improve wire survival from falling limbs, and trees. 40 to 50 pound monofilament fish line works well.
- Keep Beverage wire 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. In one wooded area, a low to the ground Beverage at my QTH is 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. If a straight run can not be maintained, good results can be obtained with less than perfect.
- 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)
- If you are near the sea, running the Beverage antenna along the beach may result in a antenna that does not work as well. You could arrange your Beverage so it starts or ends up near the waters edge to get a good ground to receive those low angle signals that tend to follow sea water.
- 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)
- 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? I tried this at my locations, and at a friends QTH. We found the slope did not change low angle vertical signal levels compared to a straight drop. We did find that unwanted high angle signals were reduced with longer slopes. Manufactured transformers are usually are wound for ~450 ohm impedance to ground. Wire height at the Beverage ends effects impedance thus the terminating
resistance (impedance) and pattern. (Use public safety when using low wires)
- 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)
- Standard published wire lengths for a Beverage from "on line" tables available are 290, 440, 600, 800 feet.
- Many find 9 feet above the ground is a good compromise height. (Crossing a roadway not included)
- 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 works well, 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 4-6 inches has an impedance about 600 ohms (depending upon wire size), and is available for about $25.00 for 1/4 mile at farm supply stores. A Western Union splice works well in case of breakage.
- In the past, tried a 680 ohm two wire Beverage antennas using electric fence wire spaced horizontally, then vertically. No reception difference noted. Found vertical spaced runs easier with out the need of cross arms.
- It is possible to achieve a large front to back ratio with a Beverage, or BOG antenna using a reverse termination. The far end is unterminated. A BOG antenna in my case gave a large front to back for protection from a cell phone installation (500 feet distant). They are using a low frequency having multiple harmonics in the HF range to scan for incomming calls. In the cell phone tower direction I used 180 feet of WD-1/A wire. The transformer utilizing a BN 202-73 core is wound 50 ohm to 150 ohm center tapped to match the WD-1/A wire. Used a 200 ohm non-inductive resistor connected from the 150 ohm winding center tap out to a ground rod. Could barely detect the interferring signal low in 160 meter band. Found it is totally nulled out ~ 1.895 MHZ. Have not attempted to adjust the wire length as expect the frequency to lower with the fall leaf vegetation drop, and snow cover of winter.
Small receiving antennas often require a pre-amplifier usually located in the radio room.
- 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 Beverage box
to reduce unwanted signals.
In cases where the coax is above ground, an effort should be taken to remove common mode signal pick up.
- Increased common mode decoupling of the coax cable was often accomplished by addng a coil of many coax turns, combined with added ground rods.. As time passed the number of turns were reduced by adding ferrite cores.
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.For increased attenuation use more turns.
- Propagation note: On 160, look for the auroras. Early after they strike the energy goes to the Earth's poles.
At that time, depending upon location, they can give great extended DX, and spotlight propagation.
- Have noticed after many meteor showers that long propagation on the low bands, especially 160 meters, is very poor or non-existent.
QRZ call search
FO0AAA receiving Delta loop. K6SE & ON4UN eham 806.
IV3PRK BOG/WOG antenna research
QTH.com Free Ham Radio Clasifieds
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 interesting 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 89.9 MHZ, listen on line at www.weru.org , a PBS Community Radio FM broadcast station. Music, programs vary with day, and time of day. My favorite is Jazz music 6-8PM weekdays eastern time zone.