The O utline of Proposed Amendment to  Ministerial O rdinance  
 
１ Item  
Partial  amendment  of the Ordinance for Enforcement of the Radio Law etc.  
 
２ Amendment to ministerial ordinance  
Ordinance for Enforcement of the Radio Law  etc. 
 
３ Reason s for amendment  
Weat her radar system  contributes to the safety and security of people's lives by 
providing weather forecasts and disaster information based on its observation results, 
and its importance is further increasing due to the increase in localized heavy rainfall 
and large -scale flooding.  
On the other hand, it has become difficult to meet specialized needs such as ensuring 
the safety of transportation and supporting hazard avoidance measures with only 
weather radar system , which is designed for wide -area monitoring. T herefore, the 
introduction of compact and inexpensive 9.7GHz  band general -purpose weather radar 
system , which can be installed and operated quickly, will make it possible to meet the 
need for early detection of weather phenomena.  
In order to meet these req uirements, we establish new provisions for 9.7GHz band 
general -purpose weather  radar system.  
 
４ Outline of the amendment  
Technical requirements of radio equipment  
Item  Technical requirements  
Name  9.7GHz band general -purpose weather radar 
system  
Frequency band  9700MHz to 9800MHz  
Aerial power indication  Q: peak power  
Observation  The observation o f precipitation of 1 mm/hr within a 
radius of 30 km.  
Distance resolution  More than 150m  
Allowable deviation of frequency  ±20×10-6 
Spurious emissions in the 
out-of-band region  40 dB lower than the average power of the 
fundamental frequency  [様式Ｂ]  
Unwanted emis sions in the 
spurious region  60 dB lower than the peak power of the 
fundamental frequency  
Allowable occupied frequency 
bandwidth  P0N: 2.5MHz  
Q0N: 2.5MHz  
Transmission 
facility 
requirements  Polarization  Horizontal or vertical and horizontal combined.  
Antenna Power  Single polarization weather radar system  : less 
than 200W  
Dual polarization weather radar system  : less than 
400W (However, vertical and horizontal 
polarization shall be less than 200 watts each. )  
Max EIRP  Single polarization weather radar s ystem  : 89dBm  
Dual polarization weather radar system  : 92dBm  
Max EIRP at a 
separation of more 
than 3 degrees 
from the main 
pointing direction  Single polarization weather radar system  : 76dBm  
Dual polarization weather radar system  : 79dBm  
Max EIRP at a  
separation of more 
than 15 degrees 
from the main 
pointing direction  Single polarization weather radar system  : 62dBm  
Dual polarization weather radar system  : 65dBm  
Amplifier  Use of solid -state elements for the end -stage 
amplifiers  
Beam width  Less tha n 4.5 degrees  
Cross -Polarization 
Discrimination  More than 25dB  
Type of radio 
waves  P0N, Q0N  
Pulse width  Using P0N radio waves : 1µs to 5µs  
Using Q0N radio waves : 20µs to 50µs  
Carrier wave 
frequency  The frequency of the carrier wave of those using P0N 
radio waves shall be 2.5 MHz away from the 
frequency of the carrier wave of those using Q0N 
radio waves.   
Modulation width 
of those using 
Q0N radio waves  1MHz to 2.5MHz  
Occupied 
Frequency 
Bandwidth  Less than 2.5MHz  
Pulse repetition 
frequency  Less than 5kHz  
Impact coefficient  Less than 10%  
The allowable 
modulated wave 
spectrum of the 
carrier wave shall 
be as follows 
attenuation from 
the carrier wave's 
aerial power  Attenuation at 
frequencies separated 
from the center 
frequency by more than 
±3.75 MHz  More than 50dB  
Attenuation at 
frequencies separated 
from the center 
frequency by more than 
±8.75 MHz  More than 60dB  
Allowable 
deviation of 
Antenna Power  -50% to +20%  
License  Licensed system  
 
５ Proposed dat e of entry into force  
January , 2023