JRG 1A-1C-8B

DRAFTING GROUP 3 -- MAGNETRONS

Interim drafting group report on the DG3 task according to JRG-46 Rev2

Introduction

This report contains the findings reached at January 2006 by the working
group on the task set by the ITU-R Joint Rapporteurs Group JRG 1A-1C-8B
in document JRG-46 Rev2 as

**JRG-DG3: Magnetron Emission Masks**

Terms-of-Reference

1\. Review the measured magnetron emission spectrum data to determine
whether there is sufficient data to reach a conclusion on whether more
stringent masks are achievable. Priority 1.

Priority 1 Milestone: December 15, 2005

Relevant JRG Contributions: JRG-14, 16, 20, 22, 40, 42

Documents JRG-DG3-01 and JRG-DG3-02 contains the basis and the work
format followed by the drafting group to formulate the required answer
to the set task and thus to formulate the basis of the work done here.

Identification of all magnetron-based radars was the starting point
followed by a search and collection for all available spectrum data to
the identification list, that was the only possible way to obtain the
data due to time constraints, massive cost of measurements and hardware
availability.

The collected spectrum data would then be used for making the assessment
on the spectrum capabilities based on criteria set in JRG-DG3-02 under
agenda item 5.

Magnetron classifications

In order to generate a check list for the spectrum data collection, a
classification or identification list for the Radars and their related
magnetrons would need to be generated covering as much of the magnetron
population available for current day technology (Ref JRG-DG3-02 Agenda
item 1&2).

This can be based on:

1.  Peak power and pulse width \*\*

2.  Frequency band \*\*

3.  Fixed /Mobile Radars

4.  Application (aeronautical, maritime, weather, space..etc) and class
    (military /civil) \*\*

5.  By RR application e.g. radiolocation /radiodetermination

6.  By technology type; cavity, linear and coaxial \*\*

\*\* Category used by Magnetron manufacturers

A reference to ITU-R recommendations in conjunction with the above table
was used to produce a more comprehensive detailed list for magnetron
based radars that resulted in the following tables:

+----------+---------------+---------+-------+----------+----------+
| **Ref    | **            | *       | *     | *        | **       |
| erence** | Description** | *Output | *Peak | *Minimum | Spectrum |
|          |               | d       | Power | Pulse    | data     |
| **System | **            | evice** | (     | width    | ava      |
| M.\[8B.8 | RD/RL^\*\*^** |         | kW)** | (µS)**   | ilable** |
| --10\]G  |               |         |       |          |          |
| Hz^\*^** |               |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| A2       | Airborne      | Tunable | 220   | 0.5      | No       |
|          | search radar  | ma      |       |          |          |
|          |               | gnetron |       |          |          |
|          | (RD)          |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| A3       | Ground        | Cavity  | 95    | 0.5      | No       |
|          | mapping       | tuned   |       |          |          |
|          |               | ma      |       |          |          |
|          | (RD)          | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| A9       | W             | Ma      | 25    | 0.2      | No       |
|          | eather/Search | gnetron |       |          |          |
|          | and           |         |       |          |          |
|          | r             |         |       |          |          |
|          | escue/mapping |         |       |          |          |
|          |               |         |       |          |          |
|          | (RD)          |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| A11      | As A9         | Ma      | 6     | 4        | No       |
|          |               | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| S1       | Sear          | Ma      | 35    | 0.1      | No       |
|          | ch/navigation | gnetron |       |          |          |
|          | (RD)          |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| S4       | Ra            | Ma      | 50    | 0.03     | No       |
|          | dionavigation | gnetron |       |          |          |
|          | (RD)          |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| S6       | Ra            | Ma      | 25    | 0.08     | Yes      |
|          | dionavigation | gnetron |       |          |          |
|          | (RD)          |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| S7       | Navi          | Ma      | 1.5   | 0.08     | Yes\*    |
|          | gation/Search | gnetron |       |          |          |
|          | (RD)          |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| S8       | Ra            | Ma      | 5     | 0.05     | Yes      |
|          | dionavigation | gnetron |       |          |          |
|          | (RD)          |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| S9       | Ra            | Ma      | 10    | 0.08     | Yes      |
|          | dionavigation | gnetron |       |          |          |
|          | (RD)          |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| G1       | Airborne      | Ma      | 0.3   | 0.3      | No       |
|          | Beacon        | gnetron |       |          |          |
|          | transponder   |         |       |          |          |
|          | (RD)          |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| G9       | M             | Ma      | 50    | 0.1      | No       |
|          | eteorological | gnetron |       |          |          |
|          | (RL)          |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| G10      | As G9         | Ma      | 250   | 0.5      | No       |
|          |               | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| G11      | As G10        | Ma      | 35    | 1.0      | No       |
|          |               | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+

\* System reference -- A(airborne) -- S(shipborne) -- G (Ground)

\*\* RD -- radiodetermination -- RL -- radiolocation

Yes\* Spectrum for 2 kW version

+----------+---------------+---------+-------+----------+----------+
| **Ref    | **            | *       | *     | *        | **       |
| erence** | Description** | *Output | *Peak | *Minimum | Spectrum |
|          |               | d       | Power | Pulse    | data     |
| **System |               | evice** | (     | width    | ava      |
| M.1638** |               |         | kW)** | (µS)**   | ilable** |
+----------+---------------+---------+-------+----------+----------+
| A        | M             | Coaxial | 250   | 2.0      | No       |
|          | eteorological | ma      |       |          |          |
|          |               | gnetron |       |          |          |
|          | Ground/ship   |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| B        | M             | Coaxial | 70    | 6.0      | No       |
|          | eteorological | ma      |       |          |          |
|          | Airborne      | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| D        | Aeronautical  | Ma      | 0.2   | 1.0      | No       |
|          | Airborne      | gnetron |       |          |          |
|          | (rad          |         |       |          |          |
|          | ionavigation) |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| F        | M             | Tunable | 250   | 0.8      | No       |
|          | eteorological | ma      |       |          |          |
|          | Ground        | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| G        | M             | Coaxial | 250   | 3.0      | No       |
|          | eteorological | ma      |       |          |          |
|          | Ground        | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| H        | As G          | Coaxial | 250   | 0.8      | No       |
|          |               | ma      |       |          |          |
|          |               | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| I        | As G          | Coaxial | 250   | 0.8      | No       |
|          |               | ma      |       |          |          |
|          |               | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| J        | As G          | Coaxial | 2.25  | 0.1      | No       |
|          |               | ma      |       |          |          |
|          |               | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| K        | As G          | Coaxial | 250   | 2.5      | No       |
|          |               | ma      |       |          |          |
|          |               | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+

+----------+---------------+---------+-------+----------+----------+
| **Ref    | **            | *       | *     | *        | **       |
| erence** | Description** | *Output | *Peak | *Minimum | Spectrum |
|          |               | d       | Power | Pulse    | data     |
| **ITU    |               | evice** | (     | width    | ava      |
| R        |               |         | kW)** | (µS)**   | ilable** |
| M.1460** |               |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| IMO/     | Maritime      | Ma      | 75    | 0.05     | No       |
|          | ra            | gnetron |       |          |          |
| Fishing  | dionavigation |         |       |          |          |
|          |               |         |       |          |          |
|          | (shipborne)   |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+

+----------+---------------+---------+-------+----------+----------+
| **Ref    | **            | *       | *     | *        | **       |
| erence** | Description** | *Output | *Peak | *Minimum | Spectrum |
|          |               | d       | Power | Pulse    | data     |
| **ITU    |               | evice** | (     | width    | ava      |
| R        |               |         | kW)** | (µS)**   | ilable** |
| M.1313** |               |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| Leisure  | Maritime      | Ma      | 10    | 0.08     | Yes      |
|          | ra            | gnetron |       |          |          |
| craft    | dionavigation |         |       |          |          |
|          |               |         |       |          |          |
|          | (shipborne)   |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| River    | As above      | Ma      | 5     | 0.05     | Yes\*    |
|          |               | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+

Yes\* Spectrum for 4kW version

+----------+---------------+---------+-------+----------+----------+
| **Ref    | **            | *       | *     | *        | **       |
| erence** | Description** | *Output | *Peak | *Minimum | Spectrum |
|          |               | d       | Power | Pulse    | data     |
| **ITU    |               | evice** | (     | width    | ava      |
| R        |               |         | kW)** | (µS)**   | ilable** |
| M.1464** |               |         |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| D        | Ground ATC    | Ma      | 450   | 1        | No       |
|          |               | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+
| H        | Ground        | Coaxial | 556   | 1        | No       |
|          | Weather       | ma      |       |          |          |
|          |               | gnetron |       |          |          |
+----------+---------------+---------+-------+----------+----------+

**[Note:]{.underline}** For all tables, the word No under "Spectrum data
available" column indicates that drafting group 3 was not able to source
/find or measure spectrum data for that class of radar.

#### Summary of ITU Recommendations for radar systems

+-------------------+--------------------+----------------------------+
| **ITU\*\*         | **Frequency        | **Radio service            |
| Recommendation**  | range**            | allocation\***             |
|                   |                    |                            |
|                   | **MHz**            |                            |
+-------------------+--------------------+----------------------------+
| 1226              | 50                 | Wind profiler radar        |
+-------------------+--------------------+----------------------------+
| 1462              | 420 - 450          | RL                         |
+-------------------+--------------------+----------------------------+
| 1227              | 1000               | Wind profiler radar        |
+-------------------+--------------------+----------------------------+
| 1463              | 1215 - 1400        | RD                         |
+-------------------+--------------------+----------------------------+
| 1464              | 2700 - 2900        | ARN + RL                   |
+-------------------+--------------------+----------------------------+
| 1460/1313         | 2900 - 3100        | RN + RL + Meteorological   |
+-------------------+--------------------+----------------------------+
| 1465              | 3100 - 3700        | RD                         |
+-------------------+--------------------+----------------------------+
| 1638              | 5250 - 5850        | RL + ARN + Meteorological  |
+-------------------+--------------------+----------------------------+
| \[8B.8 -- 10      | 8000 - 10000       | RL + ARN + MRN + RN        |
| GHz\]/1313        |                    |                            |
+-------------------+--------------------+----------------------------+
| 1644              | 13750 -- 14000     | RL + RN                    |
+-------------------+--------------------+----------------------------+
| 1730              | 15700 -- 17300     | RL                         |
+-------------------+--------------------+----------------------------+
| 1466              | 31800 - 33400      | RN                         |
+-------------------+--------------------+----------------------------+
| 1640              | 33400 - 36000      | RD                         |
+-------------------+--------------------+----------------------------+
| 1452              | 60000-61000 and    | RL(automobiles)            |
|                   |                    |                            |
|                   | 76000-77000        |                            |
+-------------------+--------------------+----------------------------+

**\*** RL -- Radiolocation RD - Radiodetermination RN -- Radionavigation

ARN -- Aeronautical radionavigation

MRN -- Maritime radionavigation

**\*\*** Radar output devices are not included in Recommendations 1226,
1227, 1452, 1462, 1465, 1466, 1640, and 1644.

In 1463 and 1730 there are no magnetron devices.

Observations

From the tables listed in the previous section of magnetron
classifications, one can clearly conclude that the portion of the
collected spectrum data is considerably less than the total number of
categories /types identified. A continued effort to collect data has not
resulted in any further gain on the position shown despite the wider
search /approach to the JRG /ITU-R WP8B communities.

This can be down to many factors most important of which is the time
scale for the work in hand versus the size of the data needed, which is
easily reflected in the number of categories, listed above.

The other problem encountered is reflected in the summary table of the
ITU-R recommendations where output devices are not specified at all,
research on some of those radar categories revealed the existence of
mixed devices in use including magnetrons. One can easily see that this
situation would make the spectrum assessments (when and if located)
extremely difficult if not impossible.

Reflecting back to the terms of reference that the drafting group was
tasked with, clearly there is a need to obtain spectrum data for most if
not all those listed above in order that a proper and correct
consideration can be made to the span of fluctuations /variation in
spectrum performance.

Collected Spectrum data

All collected spectrum data represented in plots 1-8, have been captured
using the direct method as described in ITU-R M1177 and represent
current day technology mobile marine radars utilising current day
technology magnetron devices. The identification of make and model of
those radars is not provided due to the commercial confidentiality.

Plot 1 is for a 25kW X band mobile marine radar, the plot indicates that
the resultant spectrum is well within the current roll off of
--20dB/dec. The harder roll off limit line is that of --40dB/dec and is
extremely close to the resultant (just fails).

Plot 2 is for a different 25kW X band mobile marine radar (different
radar manufacturer to that in plot 1), here the plot clearly shows that
this radar resultant spectrum fails both the --20db/dec and --40dB/dec
roll off.

Naturally the radar designs are different from the microwave (plumbing)
aspects and are not of the same size/electronics, however it is
important to note that they also incorporate different magnetrons, in
effect the magnetrons are also designed by two different magnetron
manufacturers.

Plot 3 &4 are for two different 30kW S band mobile marine radars (two
different manufacturers), resultant spectrum on both radars is within
the --20db/dec roll off limit line and breaking the --40dB/dec roll off
limit line (extremely marginal break on the radar in plot 4).

The two radars are of the same class /size but different design from
each other; here we also have two different magnetron makes in use by
the two radars.

Plot 5 is for an IMO X band mobile marine radar; the spectrum shown of
this radar in the plot is well within the limit lines of both --20dB/dec
and --40dB/dec.

Plots 6 & 7 are for 2kW and 4kW X band mobile marine radars, both are
capable of meeting the --40dB/dec roll off limit line. Both radars are
non-IMO class.

Plot 8 is for an IMO mobile marine X band radar, the resultant spectrum
clearly breaks both the 20dB/dec & -40dB/dec limit lines. It is
important to note here that this spectrum is typical of those radars
found today and represent one of the many sample spectrum data obtained
and it is worth noting that it is representative of radars out in the
field by many manufacturers (all similar spectrum).

A glance back at the obtained results and analysis above can be
summarised as follows:

-   Spectrum data obtained for this task are for marine mobile radars
    only.

-   Some existing radars in the data collected are not capable of
    meeting the --20dB/dec

-   The sample of data obtained against given type /power of radar is
    too narrow except in plot 8.

-   Different pulse width /in different radars used as well as different
    magnetrons for same class radars (at least 3 variables in a single
    equation type analysis).

-   Different antennas in use on systems for like to like comparison in
    the same class (plots 3 & 4 for e.g.) over and above the other
    variables that are different between the two radars under
    comparison.

Multiple variables in every plot "equation" would prevent accurate
analysis of the spectrum ability of a given device, as the magnetron
device spectrum performance can be seriously affected by the microwave
characteristics of the radar system using the device. A good example of
that is to consider the "what would happen" scenario if the radar in
plot 1 was fitted with the magnetron used in plot 2, these are questions
that are key to the assessment and the study, however they require full
access to the hardware and provision of the time and cost to make the
measurements. If the latter is projected on few of the plots shown
above, one could quickly see the size of the task in hand and now taking
that further to other categories of radars (or even few of them) in the
tables listed earlier in this report would make the overall task of
massive magnitude in time, efforts and cost.

A limited sample spectrum of magnetron devices measured in wave guide at
perfect load conditions supplied by a two of the major manufacturers in
UK and Japan has reflected the same pattern noted above, i.e. some do
have a roll off capabilities close to --40dB/dec and some do not (even
from the same manufacturer but with different power output device), even
when considering a fixed perfect (50 ohms) load conditions, cavity type
magnetron would deliver different spectrum performance with changes in
power and pulse width values.

SUMMARY

Spectrum data collected represented only the mobile marine radar
category from the total list identified in the work of drafting group 3
(reference document JRG-DG3-02 and this report).

Data reflected in the spectrum collected cannot enable a conclusion to
be reached on magnetron based radar spectrum agility from roll off
capabilities point of view due to the number of variations in the
available narrow sample data obtained. That portrayed by the plots has
shown variation from not able to meet --20dB/dec up to well within the
--40dB/dec limit line.

Only cavity type magnetron data was available. Although the cavity type
is widely used in commercial radar application it is most certainly not
the dominant one as coaxial magnetron based radar do also represent a
respectable portion of the total radar population picture. Linear
magnetron devices also do exist as per the magnetron manufacturers
current product data (UK and Japan), the latter is admittedly not widely
in use by radar system but never the less it is in use today.

Key areas of radar usage like Marine fixed installation Radars (VTS),
Air traffic control Radars (ATC), Aeronautical Radars and Metrological/
Weather Radars spectrum data availability are considered vital to aid
the correct consideration to be made on the span of fluctuations
/variation in spectrum performance of those radars from their magnetron
point of view.

Magnetron performance and behaviour in terms of resultant spectrum is
strongly dependent on the drive characteristics of the radar modulator
as well as the characteristics of the radar microwave system including
the antenna.

Recommendations

-   The JRG urgently needs to find a mechanism whereby the sample size
    and categories of magnetron spectra can be increased;

-   The next meeting of WP8B should be used to take forward the data
    collection process by specific requests from the JRG;

-   WP8B should be requested to identify the type of transmitter device
    used in those Recommendations listed in this report;

-   There is a need to determine whether there is radar operating in
    other bands than those listed in this report, in which there are
    currently radiodetermination allocations.

![](media/image1.png){width="6.09375in" height="4.0881944444444445in"}

Plot 1

![](media/image2.wmf){width="5.564583333333333in"
height="3.861111111111111in"}

## 

Plot 2

![](media/image3.png){width="5.9625in" height="4.0in"}

## Plot 3

![](media/image4.wmf){width="5.569444444444445in"
height="3.7729166666666667in"}

##  Plot 4

![](media/image5.png){width="5.988888888888889in"
height="4.017361111111111in"}

## Plot 5

![](media/image6.png){width="5.988888888888889in"
height="4.017361111111111in"}

## Plot 6

![](media/image7.png){width="5.988888888888889in"
height="4.017361111111111in"}

Plot 7

![](media/image8.png){width="5.988888888888889in"
height="4.017361111111111in"}

## Plot 8