The amateur radio
VHF (Very High Frequency) band is a collection of bands.
VHF bands in the amateur service cover frequencies above 30 MHz and
below 420 MHz.
This span of frequencies covers
the 6m band, 2m band, and
the 1.25m band in the amateur radio service.
Since I got my Tech+ license in 1997, I have used only
two types of omni directional 2m band antenna at my QTH.
The vast majority of the time since 1997 I
have used a home brew J-Pole.
This type of antenna is very simple, and rugged. It is
easy to build, and provides performance few commercial omni
directional antennas surpass. The tools and materials to build
such an antenna are available at most hardware stores. Special
things like RF connectors are available from many web based amateur
radio suppliers or your local Radio
Shack. Many towns also have a local electronics supply
house where all manner of electronic components can be found. It
is worth looking in (or searching) the Yellow pages in your area for
such a local supply house. If you don't offer them your
business they wont likely stay open much longer. Such are
these web/Internet times.
My home brew J-Pole
used the amateur literature as a starting point. From there I
modeled the antenna using EZNEC,
and came up with some more accurate numbers. In this way it
took less trial and error to build the antennas.
For VHF work I have the following radios:
also have a Yaesu FT-847. Although VHF capable, It spends
most of its time pulling HF duty. I bought it for its ability to
work satellites. Unfortunately AO-40 blew its brains out when its
fuel system let go, and that took some of my satellite motivation with
it. Thus the FT-847 has been relegated to HF work.
Packet RadioPacket radio (Packet Radio - TAPR, Packet radio - wikipedia)
is a form of digital communications over radio. Like the
Internet data is sent in packets composed of numerical values, which
are coded and decoded by microprocessors at each end of the
communications channel. That's about all the similarity the two
share though. Packet is by design far simpler than Internet
TCP/IP. Some of the same character encoding is used
but otherwise the two are quite different beasts. Googleing
packet radio will generate quite a few hits.
packet radio there is usually a hardware layer between the computer
managing the data, and the device that converts the data into signals a
typical amateur radio station uses to transmit signals. Such a
device is often referred to as a TNC
or Terminal Node Controller. Modern computers, with sound cards
in them, can bypass this additional hardware layer, and connect
directly to the transmitter, if they are equipped with appropriate
software. Alternatively a stand alone TNC can be used.
For packet radio I use a Kantronics
9612 Plus TNC. With the expansion of the Internet in the 1980s,
1990s, the impetus for packet radio more or less vanished. The
once almost national network, international if Canada, and Mexico are
included, has dwindled to regional or local networks. I may be
overstating packet radio's demise but it certainly is not as active as
it once was. A derivative of packet radio is APRS or rather APRS uses the packet radio protocols.
I was, and
remain, primarily interested in packet radio as a technical exercise, and a means
of collecting OSCAR
(amateur satellite) telemetry. I learned enough about packet radio
network operation to log into the local networks, and setup an APRS or two, but my real motivation
was for learning how it worked. Secondly I wanted to have
something to use on the PacSats (OSCARs implementing the Packet Radio
protocol). At any given time there is usually at least one
amateur satellite which is capable of handling packet radio signals.
Some use packet radio type protocols for telemetry only, others can store messages sent from ground stations for retrieval
later. In this
way the satellites are said to be "store and forward" packet radio
satellites. Packet Radio is just one of the digital modes used on OSCARs.
Packet Radio ReferencesYour Packet Companion, Steve Ford, (ARRL)
Practical Packet Radio, Stan Horzepa (ARRL)
AMSAT DigitalThe AMSAT-NA Digital Satellite Guide, compilation from 1994 (AMSAT-NA books)
Amateur Satellite Resource Guide