JRG --DG3 Drafting Group

**Report of the Initial Meeting on 8^th^ August 2005**

An initial meeting of the JRG-DG3 was held in the UK on the 8^th^ August
at Sperry Marine UK, the intent was to make a start on the task set by
the JRG 1A-1C-8B during its last meeting 24-26 May 2005 as stated in
document JRG-46.

A draft agenda was set and circulated reference number DG-01, a copy of
which is included at the end of this report.

(Individuals full details are listed in the registration of the JRG
1A-1C-8B 2^nd^ meeting, document "JRG 1A-1C-8B Registration List
5-05Rev2.doc")

List of attendees:

Peter Griffiths

Graham Parfitt

Len English

Mike Scorer

Ivan Boswell

Adil Abbas

Apologies received from:

Martin Edwards

Andy Stove

John Holloway

Stephen Parry

Mike Pope

Steve Moss

The meeting was set to proceed despite the short notice and the
reduction in the number of experts available due to the shortage of time
remaining to the milestone set on the task @ December 15^th^ 2005.

The intent was to set a ground and a start on the task analysis and way
forward by all those available such that to attract all remaining
experts to participate and contribute via correspondences.

The task set for JRG-DG3 by the JRG 1A-1C-8B during its last meeting
24-26 May 2005 was included in the agenda (DG3-01) for reference.

The Proposed draft agenda was approved with no modifications.

**Agenda item 1 & 2:**

A review of magnetron based Radar spectrum data available for analysis
indicated that the bulk of the data available at the meeting are from
mobile Marine type Radar (at various power levels), there was a clear
lack /non availability of spectrum data for:

Marine fixed installation Radars (VTS)

Air traffic control Radars (ATC)

Aeronautical Radars

Metrological and Weather Radars

Clearly there is a need to obtain spectrum data for those listed above
so that a proper consideration can be made to the span of fluctuations
/variation in spectrum performance, the proposed way forward was to
request help from all other members of the JRG that has expressed an
interest or can help /contribute to the work of this group to generate
/gather what is available in spectrum measurements on those other types
of Radars.

A key point was made to the latter is that we must ensure that all
collected data are representative of CURRENT technology magnetrons
/Radars so the analysis is not based on very old devices that may or
will be of a poor spectrum performance.

A key issue here is to ensure as much as possible that all collected
data for the analysis are captured using the same method /technique,
this so far has been the direct method of M1177.

**Agenda item 3:**

Our task clearly relates to all magnetron based radars and thus a
complete assessment of that must include most if not all types of
magnetron based radars in operation now (to say the least) and thus a
way forward can only start by the technical examination of the spectrum
data relating to those radars.

As highlighted above, currently any real and reliable data available to
the team (so fare) is for mobile marine radars with a long list of
missing spectrum data for the other highlighted types of radars, the
time required to obtain those data sets is considerably long and if non
are available (and to the notes /key issue stated above). The time to
collect the needed spectrum data can only be determined after we find
out what is available and thus a start will be made by requesting that
from all existing experts who has expressed an interest in the work of
this group and the wider Radar community via the JRG and the RCG. In
summary to this point, if most of the data needed is not available then
it is feared that the time scale to get that is beyond 2006 (at a good
guess).

**Agenda item 4:**

Additional spectrum data will be contributed from all members that have
attended this meeting by end of August; those data will include weather
radar but currently does not include ATC or VTS radars.

A request will need to be made to all that can contribute with spectrum
data; this will also include a direct request from all interested
experts in JRG-DG3 work (USA and JAPAN combined with all inputs from the
UK).

**Agenda item 5:**

As indicated earlier in this report re the current non availability of
spectrum data covering the types of radars specified above (as a
minimum) would prevent correct representative assessment to be made at
this stage however all the experts present in the meeting agreed that it
would be useful to define a list assessment criteria that one could work
to in the future as the data collection is being made.

Proposed assessment criteria to aid the decision on a harder roll off
and more efficient spectrum (B --40 bandwidth) are selected to be:
(applies to both X and S band)

-   Main mode output profile symmetry

-   Rate of roll off

-   The presence of modes other than main mode (∏-1, and others)

-   Mode mixing.

The above list is by no means exhaustive but it does make a start on the
route of making a ground for the assessment /considerations. More can be
added later should be deemed necessary as an input from other experts.

Important point to note here, is that all the listed criteria above
would be influenced and affected by the type of radar construction,
parameters like the antenna type (slotted waveguide or patch array),
RoJo and the output coupling mechanism (waveguide fed or pin coupled),
care must be taken to collect sufficient spectrum data that covers the
key points raised above.

**Agenda item 6:**

The situation in here has been made worse by the current method of
measurement as some of the data available have been captured using the
indirect approach, a valid comparison /examination. Since the initial
meeting had only a limited and narrow scope of the total data required
thus this agenda point action is deferred till a reasonable and reliable
set of spectrum data have been collected.

**Agenda item 7:**

Magnetrons can vary in their spectrum and installation requirements
depending on their construction and operational parameters (some are;
frequency, power, coupling, drive characteristics) and thus when
considering filtration techniques (and their suitability /applicability
and capability) one would need to take a slight closer look to the
device in concern. Magnetrons that are used in commercial Radars
represent by far the majority of the type in use and the volume; there
are two key manufacturers for commercial magnetrons divided between the
UK and JAPAN. It was deemed a good idea to approach those manufacturers
(E2V and New JRC) to provide spectrum data and characteristics of
popular and common magnetron device as well as seek their consultation
on compatibility and requirements on the use of filters. The latter does
not imply that other non-popular or special magnetron will be ignored or
missed from the assessment.

This idea behind this is most simple; it starts with making a graphical
assessment of the "raw" magnetron spectrum from roll off capability and
40dB bandwidth, should the "raw" profile be significantly poor in terms
of meeting a harder requirements then it will be even worse when
operated in a Radar (due to match, VSWR, modes, isolation. Etc).

It was clearly noted that current generation magnetrons have improved
dramatically over the older generation from many aspects over the years
but fundamentally they are still very close in their behavioural
characteristics to those from the older generations. It is important to
note that document JRG-20 had contained relevant data on this subject
and thus it is advisable that a check will need to be made with the
author on any update to the information contained in the document.

**Agenda item 8:**

Considering the size of the task as clarified by all the points in this
report, all experts in the meeting agreed that we will not be able to
draw out any results by at least mid 2006 (unless most of the data
needed become available in a very short time). It was strongly agreed by
all that it would be haphazard to attempt make any assessment worthy of
proper consideration on the limited and varied set of results available
at the point of the meeting.

The meeting has certainly been very successful in providing a close
examination and assessment on the size of the task in hand, which has
been made more complex by issues relating to the method of measurement.

Having stated the latter, all those present has agreed that we do not
need to collect massive set of data but a representative data for known
or the majority type of Radars /magnetron would be sufficient it was
also accepted in the meeting that it would be acceptable to select a
"popular" type of radar for each group /class, for example section of a
popular or widely used ATC radar as a representative for the family of
ATC, this will greatly depend on the availability of spectrum data for
that kind and the knowledge of the different types of members in its
family.

It was strongly agreed that such assessment could be easily made on
mobile marine type Radars.

At this stage, it is impossible to attempt to draw out any conclusions
on this point.

**Agenda item 9:**

-   Provide any spectrum Data (excel) available done under direct
    method. **All**

-   Contact JRG members from USA and JAPAN for spectrum data. **Adil
    Abbas**

-   Contact E2V and New JRC for "raw" magnetron data. **Adil Abbas**

-   Group and organise contributed data. **Adil Abbas**

-   Send sorted data to all by week 44 (wk beginning Oct 24^th^). **Adil
    Abbas**

-   Provide any update on the information contained in JRG-20. **Martin
    Edwards**

**Agenda item 10& 11:**

> The format of the final report has not been agreed so far, it was
> deemed logical to start with available data /possible contribution
> before the format can be agreed.
>
> The preliminary date for the output report has been set for week 48
> (wk beginning Nov 21^st^).

**Agenda item 12:**

None

End

Copy Of the Agenda set:

JRG --DG3 Drafting Group

**Draft Agenda for the Initial Meeting at Sperry Marine UK on 8^th^
August 2005**

# Our task as set by the JRG 1A-1C-8B during its last meeting 24-26 May 2005 in document JRG-46 as follows:

**[JRG-DG3: Magnetron Emission Masks:]{.underline}**

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 Milestone: December 15, 2005

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

Please note that further to that the document JRG-34 is also now added
to our terms of references.

Proposed Points:

1)  What spectrum data we have to date? What type of Radars do they
    cover (Marine, ATC..etc)

2)  Identify all additional spectrum data needed.

3)  Overview on size of work of point 2 above with time estimate.

4)  Devise a work plan for data collection and potential contributors.

5)  Technical review of available data for initial roll off assessments
    and spectrum profile.

6)  List all possible parameters that could prevent the possibility of
    harder roll off including main mode output symmetry, rise and fall
    time of main mode, 40 dB bandwidth.

7)  Use 5 and 6 above to derive an initial view on the limiting factors
    of the technology in use and the method(s) /technique(s) that may
    overcome it.

8)  Can the work be completed in the set time scales? If not then what
    would be achieved in the set time frame and could a result be drawn
    from it?

9)  Task allocation for further contributions.

10) Determine the format of the group output.

11) Set a date for the group output.

12) AOB & Way Forward.

> Close 1700