12 December 2017
the transmitting and receiving units, it’s difficult to say for
sure. Estimates range from a few miles to over 10 miles.
According to the laws of physics, you get more range at the
lower frequencies for a given power and receiver sensitivity
than at the higher frequencies. If you don’t have clear line-of-sight (LOS) between the transmit and receive antennas,
the signal will be greatly attenuated or even blocked
completely. With antennas high and in the clear, the range
is greatly increased.
For MURS, you can use any antenna you want. It
doesn’t have to be attached to the radio as is the case with
FRS radios. A typical quarter wave vertical needs to be
about 19 inches long at the operational frequencies, but
most handheld antennas are of the helix variety and much
You can use a gain antenna like a collinear or Yagi
connected remotely. The main restriction is that the
antenna may not be more than 60 feet off the ground or
more than 20 feet above any structure it is attached to.
With a gain antenna, the effective radiated power
(ERP) will be higher than the two watt maximum
authorized, but the signal will be directional where most of
the signal will be focused into a beam rather than covering
a wide azimuth. That’s a good thing.
You can use MURS anywhere in the US and in most
of the US island possessions. Some restrictions apply in
Puerto Rico. Operation from an airplane is prohibited, but
you can use MURS on any sea vessel.
You must use MURS radios that have been built and
tested to MURS standards. In other words, you cannot
build your own radios.
A couple of key limitations are that repeaters may not
be used. In addition, you cannot connect a MURS radio to
the public switched telephone network.
An Unexpected Internet of Things Option
The Internet of Things (Io T) is a hot topic today. There
is a massive effort to connect everyone and anything
wirelessly. The examples are too many to list here, but you
probably have several items that could be classified as Io T
like Bluetooth headsets or speakers; personal assistants like
Amazon Alexa, Google Assistant, Microsoft Cortana, or
Apple Siri; or a smart watch.
Most of these devices use Wi-Fi or Bluetooth in the
unlicensed bands of 2. 4 to 2.4845 GHz, 5. 8 GHz, or 902-
928 MHz. Other radio technologies like IEEE 802.15.4,
ZigBee, and Z-Wave use these frequencies.
Range is inherently restricted at the higher frequencies
as described earlier, but low power also restricts range
to about 30-300 feet. That’s generally a good thing as it
minimizes interference between devices. If you’re looking
for longer range, other technologies have emerged. MURS
is one of them.
One of the most popular longer range Io T technologies
is called LoRa; it’s a standard and product of Semtech. It
operates in the 902-928 MHz band, and stated range can
be several kilometers. MURS beats that.
If you really need long range of multiple miles, MURS
is certainly worth a look. It’s great for data gathering
telemetry, or remote monitoring and control of remote
Two-way handheld radios are widely available online.
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Recent Changes to the Personal Communications Services
In May 2017, the FCC announced some proposed revisions
to Part 95 that affect the CB, FRS, and GMRS services.
These are detailed in the FCC documents 17-57, and the
Notice of Proposed Rulemaking (NPRM) WT Docket 10-119
that you can get on the FCC website. A quickie summary is
Citizens Band Radio Service (CBRS)
• Changed the name from Citizens Band to Citizens Band
Radio Service (CBRS).
• Bluetooth or other wireless microphones are now
• The 155 mile limit imposed on communications contacts
is eliminated. This lets CB users on the 27 MHz band
contact any other station regardless of distance. CB
owners can now operate more like hams.
Family Radio Service (FRS)
• Eight new channels that are shared with GMRS.
• Power output boosted from 0.5 watts to two watts on the
General Mobile Radio Service (GMRS)
• More assigned channels to be shared with FRS.
• License term extended from five to 10 years.
See the FCC documents mentioned above for details.