Product Review
Nagoya NA-771G
GMRS
Gain Antenna
SMA Female
& SMA Male
John 'Miklor' K3NXU
What is a Nagoya NA-771G
The Nagoya NA-771G is a single band
antenna designed specifically for GMRS transceivers.
The wrong antenna, even if longer,
can decrease the performance of the transceiver, and
possibly cause damage. A longer antenna does not
necessary mean better.
A common misconception is that a VHF/UHF antenna is capable of
covering the entire spectrum when in fact they are tuned
to cover specific frequencies within that range.
To confirm the characteristics of the NA-771G, I used an analyzer to determine the
resonant frequency. The antenna 'sweet spot'
was at 462MHz and showed a respectable SWR of approximately 1.7:1
This is exactly what you need at GMRS frequencies.
Nagoya 771G
click to enlarge |
The analyzer also shows a notch at 174MHz which can be
ignored as this antenna is specific to GMRS.
Although some dual band antennas are labeled as VHF/UHF, this does not mean they are broad banded.
Many dual band antennas are also very frequency specific.
Using a standard dual band ham antenna on
GMRS could cause undesirable results. The graph below
shows the resonant frequencies of a typical ham antenna.
Note that the ham antenna is tuned perfectly to 146 and
447MHz, however the SWR at 460MHz is above 8:1 and nearing infinity.
This could result in poor performance and possible radio
damage.
Typical dual band
ham antenna.
click to enlarge |
Base Connector
GMRS handhelds are available in both SMA Male and Female
form factors. The NA771G is now available in either
style. Be sure to order the antenna with the proper
base.
The images below show both Male and Female.
 
Male
Female
click to enlarge |
Antenna Gain
The NA-771G is a 5/8 wave antenna at GMRS frequencies. The
difference between a 1/4 wavelength (found on most
handheld radios) and 5/8 wavelength antenna is 2.6db.
This brings the gain to 4.75dBi at GMRS frequencies.
For reference, 3.0db gain is the equivalent of doubling
your power.
Ref Link:
5/8 wave Vertical Antenna
Ref Link:
5/8 wave Gain over a 1/4 wave
Over-the-Air Testing
For testing purposes, I used a GMRS handheld with a
stock antenna.
Although the radio performed well, there was a
definite performance increase when switching to the
NA-771G on both transmit and receive.
Very Important
When purchasing an antenna, quality and precision is
critical. Beware of counterfeit or 'fake' antennas on the
market. They look authentic but the appearance doesn't
make the antenna perform. For that reason Nagoya has
published a page on how to determine whether the antenna
is authentic. Here is a link to that article.
How to identify a Fake Nagoya antenna
Conclusion
This Nagoya NA-771G antenna is 15.3" long, comes with an SMA-female connector,
a small rubber O-ring grommet to assure a snug fit if
necessary and provides a solid 2.6dB over a standard 1/4
wavelength antenna.
I give this one
a two thumbs up on GMRS.
Available from
BTech
and
Amazon:
NA-771G (GMRS) Female
NA-771G (GMRS)
Male
Note: This antenna was received for the purpose of a
fair and unbiased review. All findings are factual based
on the equipment I received. Any issues (if found) have
been reported both here and back to the seller or
manufacturer.
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