rachiele@NADC (10/17/85)
What does the term "beverages" mean? Is this some type of equipment or what?
I have never heard that term before.
Jim
KA3OKPYOUNG@MARLBORO.DEC.COM (10/17/85)
A Beverage antenna (named after a person, not a soft drink) is a directional
receiving antenna. In it's simplest form it looks like this:
------------------- // ---------------------
| |
--- \
Coax / Terminating
--- \ Resistor
| /
| |
----- -----
--- ---
- -
It's input impedance is usually around 300-500 ohms, so a 4:1 transformer
is often used to connect to the coax. The wire is not very high; 3 to 10
feet is typical. A good beverage is long. A half wavelength is considered
short, a wavelength is probably about the minimum where it is worthwhile
to install one. I know of some beverages for 80 and 160 which are 1500 feet
long or more!
The directivity is in the direction of the resistor. For the antenna
pictured above, it is like this:
\
\
==========================>
/
/
The resistor is usually about 470 ohms, although the exact value for best
front to back depends on height, length, and ground conductivity. Some
people use a potentiometer and adjust it for best results.
The antenna has loss as compared to a dipole, so it is never used as a
transmitting antenna. Many radios require an external preamp when used
with a beverage. Because the directivity of the beverage cuts down on
the noise (remember, for receiving it's not signal strength, but signal
to noise ratio that's important) it is possible to copy signals on a
beverage which cannot be heard on a dipole or vertical.
Beverages are seldom used above 40 meters, since stations big enough to
justify beverages have directive antennas on the higher bands. Even
on 40 meters, they are not tremendously popular. But on 80 and 160,
I have not heard anything which works as well.
There are people who use unterminated beverages, which are bidirectional,
and there are designs for 2 wire beverages where the directivity is
steerable. But when most people refer to a beverage, they are talking
about the simple 1 wire terminated antenna.
Paul Young, K1XM
--------jhs@mitre-bedford.ARPA (10/18/85)
He doesn't know what beverages are? Why, they are things that you drink! There is a technical term also -- a Beverage antenna is a long, low, highly directional traveling wave antenna. According to the ARRL Antenna Handbook, anything over one wavelength is effective, but the directionality and gain will improve if you make it longer. A height of 10 to 20 feet above ground is about right. The far end (in the favored direction) should be terminated in a resistor which should ideally be equal to the characteristic impedance of the antenna, which acts like an unbalanced transmission line. The ARRL book says 500 to 600 ohms is a typical impedance. At the feedpoint, a matching network is needed to match the 500 - 600 ohms to the feed line. Or else open wire line of this impedance can be used to bring the signal to the receiver, but then a matching network may be needed at that point. The Beverage antenna is said to be very effective for DX reception from a single direction. If you use it for transmitting, half the power is lost in the terminating resistor, but you do get gain and directivity. Having never used one, that's about all I know about it. 73, John S., W3IKG
dm_johnson@manana.DEC (10/20/85)
Probably the reference to Beverages is to a beverage antenna. It is usually used in low freq ranges, is a coupld of wavelengths long and low to the ground and terminated. Provides some directional characteristics gain and reduced noise. You need lots of room although I do remember seeing an article by a Pacific ham who used a short variation on 40 meters to communicate back to the states. He oriented the antenna to knock out a broadcast station in Japan or so. The claim was effective for the money involved. Denny ka1bqz
ai2q@ky2d-2.UUCP (Alex) (10/21/85)
> > What does the term "beverages" mean? Is this some type of equipment or what? > I have never heard that term before. > Jim > KA3OKP *** REPLACE THIS LINE WITH YOUR MESSAGE *** Hi Jim: The term is a proper noun as it is the name of an antenna named after an engineer called Beverage. The antenna is very long, highly directive, exhibits exceptional gain, and is noted for its low height above ground. Beverage antennas are often used by serious longwave and 160 meter enthusiasts. You do have to be careful however so you don't trip over then while out inspecting the antenna farm. They're usuallly only a few feet above the ground and, by the way, work best over sandy or rocky terrain. I have detailed info here somewhere; let me know if you want more poop. Until then, very 73 de Alex, AI2Q, Freeport, Long Island >>AR>>