Introduction
Details of the
development of radio equipment for ionospheric research are well documented and
it was as a result of this early work that it was realised the techniques
developed could also be used for the detection of transmissions reflected from
objects below the level of the atmospheric levels being studied. This resulted in
the use similar equipment for measuring the range of aircraft or shipping, as
well as for land masses.
The value of these
capabilities was recognised in many countries including the UK, Germany and the USA which resulted in further research to produce
prototype outfits for military use. Initial work in UK concentrated on the provision of radio
equipment for determining the range and direction of aircraft to improve
defence against air attack and later for use in controlling anti-aircraft
weapons both on warships and ashore. In order to preserve the secret nature of
this work in the UK it was designated as being RDF or Radiolocation,.
However in 1942 this type of equipment became known as Radar in the RN and USN.
New Zealand scientists had been involved in research work
associated with use of radio equipment for the investigation changes in
atmospheric and weather conditions since Edward Rutherford arrived in Cambridge in 1895. He had already carried out radio
research in New Zealand and initially continued to investigate the propagation
of electromagnetic waves before moving on to nuclear physics. Nevertheless he
was aware of the development activities at Bawdsey
which lead to the establishment of an aircraft warning system (CH). This was
the first national defence radar system of this type and was in operational use
by early 1939. His prominence in scientific activities in UK enabled Rutherford to arrange for loan of equipment to assist in
research being undertaken in New Zealand universities. More importantly he encouraged
the recruitment of graduates from New Zealand to the UK to join research teams concerned with radio
research.
On of these was Ernest
Marsden who joined the Cavendish Laboratory in Cambridge to work on radio propagation and later became Director
of Scientific Development which had been established to support radio research
in New
Zealand and had been provided with funding by the Committee of Imperial
Defence in London. The basic overall philosophy in 1939 was that
technical details of the developments in radar were to be shared by New Zealand as well as with the other three major
dominions of the British
Empire. These
countries were asked to send a physicist to study the current state of radio
research and radar equipment being developed in UK so as to assist in the introduction and use of
radar for their own defence. Dr Marsden was selected
to represent New Zealand.
He arrived in England during April 1939 and visited Bawdsey and other establishment involved in radar
development. As a result he was able to easily absorb the fundamentals and
techniques associated with entire new type of equipment and before his return
had been able to arrange for future supply to New Zealand of technical data, procedures and also for supply
of components essential for production of radar equipment. He also obtained
vital items of hardware which were not available locally. These included
co-axial cable, oscilloscopes and two television receivers, from the design of
which radar receiving units had been developed in UK. In addition he also brought components of the
newly available radar fitted in RAF aircraft (Air-Surface vessel (ASV) Mk 1) for
use in New
Zealand.
His primary objectives
were to design and manufacture radar equipment needed for warning of the approach
of aircraft and ships to be fitted in warships and ashore, as well as
fire-control radar equipment which could be use on ships or on shore. Two
highly secret teams were then set up, one in Christchurch to develop equipment
for shipboard use and the second at Wellington to develop to develop a fire
control equipment for shore defence against ship attack and also a radar
suitable for use in aircraft.
Despite the enormous
difficulties caused by lack of suitable scientific staff and inadequate
up-to-date publications needed to understand the new scientific techniques
being used amazing progress was made. One of the difficulties encounter was
that needs of meeting priorities took precedence over the equally important
requirement to organise the work in a way which would avoid duplication of
effort available.
After the development
of suitable equipment designed to operate on microwave frequencies, made
possible by the use of magnetron valves, Dr Marsden
visited UK again early in 1941 and before return to New Zealand also visited the USA and Canada. During his absence many the basic radar programme had been re-organised but he was able to take
steps to ensure that he remained responsible for organising all aspects of
research, development and production of radar equipment in New Zealand. An offer to supply New Zealand radar to RN ships
in Singapore was made but the numbers offered proved over optimistic and in any
case the fewer fire control sets completed were never delivered, and one may
have been taken from the NZ mercantile HAURAKI during passage to Ceylon in the
Indian Ocean on 12th July 1942 where it was intercepted by a Japanese surface
raider.
1 9 3 9 t o 1 9 4 3
HMNZS Achilles (NP, click for enlargement)
After the outbreak of
war with Japan the reliance placed by New Zealand that imperial support from London would always be available was reduced and
arrangements had been made to obtain to obtain advice and support from the USA together with components required for
production of microwave radar equipment. As a result it is clear that most
radar equipment manufactured in New Zealand was microwave equipment, especially equipment
required for shore use for aircraft or ship warning and capable of transport to
isolated positions in the Pacific
Ocean. After 1943
little radar equipment was produced in New Zealand and RNZN warships were then provided with
British outfits to replace the earlier New Zealand sets.
The first radar
equipment produced in New Zealand was not identified by using those used by the
RN or the USN although those used are similar enough to recognise. However in
the case of Air-Surface Vessel radar (ASV) fitted in aircraft there were two
types, Mk1 and Mk2 which used different frequencies. The first NZ prototype
equipments some components obtained from UK in 1939 and used a transmitter frequency of 45
MHz and later types were designed using frequencies about 200MHz similar to
equipment developed in UK. A Homing Beacon for use with ASV radar sets
was produced in New Zealand. UK ASV Mk2 was later solely used by the RNZAF
The British ASV radar
used in RAF aircraft was fitted in the WALRUS aircraft carried on board HMS
ACHILLES. A second radar of this type was fitted for
use on board with a modified aerial unit to suit this use. Further details are
required about this type of installation. The modified ship variant was also
fitted later in HMS LEANDER and a production model installed in HMS MONOWAI.
All radar designed in New Zealand before 1942 used a frequency below 500M/c as
insufficient information and no suitable hardware was obtainable until details
of microwave technology and information could be provided. Some difficulties
were experience in obtaining compatible components locally was experienced and
other items were dependant on supply from UK or elsewhere. No mass Production facilities
were available
HM Cruiser ACHILLES
was the first Royal Navy cruiser to be fitted with fire control radar,
identified as SS1, in July 1940. The first trials of this type of equipment
were not carried out on the British equivalent until November that year. It is
clear that New Zealand design equipment for surface defence was in operational
use before 1941 and that some design techniques such as use of rack fitting
instead of cabinets with inferior access to wiring and components were
developed and in use much earlier than in RN equipment.
NEW
ZEALAND RADAR EQUIPMENT
HMNZS Leander (NP/Mark Teadham, click for
enlargement)
SS Type Radar (Later SWG)
Unlike the British
Types 285 and 284 radars which used a wavelength of 50cm, the first model
fitted in HMS ACHILLES used a wavelength of 66cm and the later model fitted in
August 1942 (SS1) used 73cm wavelength. The aerial unit, mounted on the 6
armament Gunnery Director was made up of two dipoles, one for transmission and
the other for reception. and were mounted in single
cylindrical paraboloid reflector. The 5kw transmitter
was a pair of self squegging VT90 oscillators with
pulse output at 2000cps, which replaced a lower power design The
receiver was a super-heterodyne with a line tuned mixer feeding a 45m/c IF
Amplifier from a PYE television receiver. A 4 CRT was used to display a 30.000
yd. time base with calibration markers at 1,000 yards.
A prototype model was also fitted in HM Armed Merchant Cruiser MONOWAI.
In August 1941 this
model was replaced by a modified design (SS1) which was fitted to HMS ACHILLES
and HM Cruiser LEANDER. These two ships were transferred to the RNZN when the
RN New Zealand Division of the RN was replaced. The modified version had a
wavelength of 73 cm and greater transmitter power output was available using HF110
valves. A new design aerial unit mounted within a paraboloid reflector sited on
the 6 armament director including had two Yagi
design elements, each having 13 additional dipoles acting as directors and one
folded dipole radiator. This change gave better bearing accuracy and detection
at a greater range. Improved display facilities were available, a local
indicator using an elliptical display to provide either a slow time base for
normal use, or a fast time base for accurate ranging. Another 5 CRT was used
to assist in training of the director presumably mounted in the director.
Another set of the modified version was fitted in the HMZNS MONOWAI being used
as an AMC before conversion to an LSI(L) during 1943.
Another fitting in HM Cruiser CANBERRA (RAN) is to be confirmed.
SWG Type Radar
This equipment was
based on the modified Type SS1 and used a slightly longer wavelength with a two
different design aerial units available. The ship
borne version was similar to that used Type SS1 and was mounted on the gunnery
director. The alternative framework aerial was mounted on a Pylon and had four Yagi type arranged in pairs, the upper being used for transmission
and the lower pair for reception. Each Yagi had a
folded dipole radiator and eight director dipoles with an associated trigonal reflector. Fit of this improved design in both cruisers
is to be confirmed but this is possible as both ships were deployed based at Auckland in late 1942. Eight of this Type were delivered for RNZN use. How the aerials were sited is
difficult to determine!
A Type Radar
A
prototype equipment for
provision of warning of aircraft or surface approach was produced in 1940 using
components and techniques provided from UK. The design was similar to that used for the
RN Type 286M but used a much larger aerial unit of Yagi
design. A modified aerial unit was designed locally for ship fits as the
aircraft design was not suitable in for ship fits. This unit comprised two
elements one for transmission with a folded dipole and the receiving unit with
a reflector. Each type had either three or five dipole units. Transmission of
two microsecond 7 KW pulses was provided by a squegging
oscillator at a repetition rate between 800 and 1200 cycles per second. A
super-heterodyne receiver with a 4 M/cs bandwidth was
used and an A type Display was provided with calibration markers.
Land Based Radar.
This type of radar was
given 2nd Priority for development and two types were introduced.,
one for coastal watching to give warning of the approach of shipping (CWS) and
another for fire-control of shore batteries sited for defence against seaborne
attacks. Both types utilised techniques based use of metric wavelength and were
similar to the ship fitted equipment. These shore radars both used stack
Broadside aerial arrays were made transportable with their own power supplies.
CWS Type Radar
The first operational
outfit fitted in a manually rotated hut used a 200 M/c transmitter using a squegging oscillator to provide two microsecond pulses with
a repetition rate of 1,500 c/s at power of about 7 KW. The super-heterodyne
receiver outfit had an IF frequency of 45 M/cs and a
15cm CRT provided an A Type Display outfit to show received signals out to
over 30 miles or more if site was at a higher elevation. The aerial outfit was
rotated by hand and initially mounted on the side of the hut. It comprised four
stacks of dipoles, the centre two being used for transmission and the outer
stacks for reception. A wire netting reflector was used behind the dipole
units. In later models the Aerial was separately mounted and driven by coaxial
cable. Both variants were subject to difficulties in rotation in strong winds.
These outfits were used until 1943/44 when microwave radar became available.
CD Type Radar
The equipment
initially used for fire control of shore batteries was identical with the CWS
except that two manually rotated huts were used, each with the same design four
element aerial unit and a 30cm CRT used for display of
received beam switched signals. Synchronisation of rotation was totally de[pendent on telephone communication between the two
operators! Range of detection was again dependant on height of the site.
Later variants
incorporated many improvements including coaxial resonator tuning of the RF and
Local Oscillator stages on the receiver, use of a single five stack aerial unit
mounted on only one hut, and improved display of received signals. The aerial
consisted of 40 dipole units, the centre three used for transmission and the
two outer for reception. A wire netting reflector was
used as in the four stack design, Three displays were
available in the improved variant: a 12 CRT for general observation, a 5 CRT
to provide an accurate presentation of a 3,000 yard portion and a 5 CRT to
provide bearing data. The beam switched signal from the two
receiving aerials were shown side by side and when of equal height equal
indicated accurate target bearing. Later units of this improved design were
manufactured by local industry until microwave equipment was available.
Offers of New
Zealand Design radars to other countries
During 1941 before the
entry of Japan into WW2 enquiries were made by the Admiralty
in London to ascertain whether any New Zealand design equipment could be provided for use by
RN warships based in Singapore. Although five SW Type radars and five SG Type
were promised, but later only 24 of an increased order of the SG Type were
completed. the first in February 1942. In all 15 were
sent to Singapore but none were delivered for operational use
before the surrender of Singapore. It is known that of the nine sent to Colombo, one on board the NZ mercantile HAURAKI fell
into Japanese hands when this ship was intercepted by a Japanese warship. Seven
were sent to Sydney later in 1942 to be held as a reserve for the
Eastern Fleet
Microwave Radar equipment manufactured in New
Zealand
Production was delayed
for many reasons the principal ones being lack of experience in waveguide
technology and limited availability of components such as magnetrons, spark
gaps and other RF units. Notwithstanding these difficulties and despite
political problems relating to the release of complete New Zealand equipment
direct to the USA; both completed equipment and personnel to train operators as
well to provide scientific support supervise of maintenance and repair, these
were provided and made a significant contribution to operations during the US advance
towards the Japanese mainland in 1944-45. The microwave equipment could either
be used a fixed site or a mobile unit for warning of the approach of low flying
aircraft and shipping. Another New Zealand radar designed for the RNZAF specifically
ordered by the US Navy for use by Assault Teams to provide Long Radar Warning
was completely mobile and consisted of three trucks containing radar sets,
operational control display equipment, power supplies and repair facilities
with spares and documentation.
A
prototype radar set was
produced for gunnery fire control but the project was later cancelled.
Radar Type ME1 (Land Based Warning Radar.
Land based outfit microwave
radar using 10cm magnetron transmitter and intended for use on a fixed site or
as a mobile station. The radiated output varied dependant upon the design of
magnetron used and provided a two microsecond pulse with a 500m/c repetition rate.
The associated super-heterodyne receiver had a 24 M/c with 1M/c Bandwidth. using a crystal mixer and Sutton Tube Local oscillator. A Spark Gap unit (T/R Switch). enabled
use of a single paraboloid, rotating aerial with waveguide feed and rotating joints.
This unit was initially mounted on a rear platform was later positioned on the
rook of the radar truck. The Display equipment included 5 CRT (Plan Position
Indicator PPI) for the first time in a New Zealand radar and provided a plan
view of the received signal by use of a rotating time base in synchroniism with
the power driven aerial. A 5 A Display was also available with calibration
markers. for ranging purposes. These items together
with a Plotting Table for assessment of the current tactical situation and the
associated command and communication facilities were housed the radar truck
A second truck was
used for power generation equipment using either petrol or diesel driven
generators, which also contained suitable repair facilities including had tools
and more importantly electronic test equipment produced in New Zealand. This equipment was mounted in trays which
were removable and wiring was located in the upper side with major components
underneath to facilitate testing and replacement, This
innovation was available in New Zealand radars at least 12 months before introduced
into RN designed equipment and ME1 radars were deployed in the Pacific theatre
well in advance of suitable. US and UK outfits.
An improved outfit
known as ME1A had a larger aerial and a higher power magnetron. The rf arrangements were improved to
increase accuracy of alignment of the rotating element and stability of the
transfer of rf to the aerial. Changes were made of
some receiver components which had proved to be under-rated, and two 6KVA
diesel generators used for power supply in the second truck.
LRAW Type (Long Range air
Warning)
This equipment,
originally designed for the RNZAF, was ordered by the US Navy for use by ARGOS assault unjts to
provide early warning of aircraft approach during deployments in the Pacific.
Its primary significance was that it was transportable in a Landing Craft and
could be brought into service more rapidly than the US 270 equipment under combat
conditions. Three trucks were required for operational use of LRAW and
its rapidity of operational availability was increased by the provision of two
aerial units. Two New Zealand scientists were used to provide support during
operational use and served with great distinction to ensure maximum value of
this type of defence. The first was deployed operationally in February 1944
when it was used during landings on Nissan Islands in the Solomons and five others were used
in later assault operations.
To obtain long range
warning a lower frequency of 97 M/c was required and 10 microsecond pulses were
available at 50 cycles per second with 150-200 KW peak power for two NT99
output valves.
A Yagi
type aerial unit was used to set up the equipment on arrival at the selected
site and was transported as a demountable unit during transit and then fitted
to a gearbox on the roof of the radar truck. The aerial unit consisted of two
separate arrays with dipole elements used for transmission and reception. On arrival at the selected site, installation on the roof
of the radar truck took less than an hour and the array could then be rotated
by an electric motor.
A larger Broadside
array was transported with its mounting tower in another truck. It comprised 18
dipoles arranged in three stacks the centre one being used for transmission and
the two outer stacks for reception. When time allowed the array was assembled
near the radar truck and was rotated by an electric motor. The procedure took
less than an hour.
A super-heterodyne
receiver with an IF of 24 M/cs and as bandwidth of
250 K/cs was used to feed a 9 CRT display with
ranges of 10miles and 200 miles calibrated at 10 mile intervals. Performance
with the Yagi aerial was 90 miles on single aircraft and up
to 125 miles on groups. With the Broadside array these were 100miles at 5,000
feet and over 150 on group at 10,00 feet. Range
accuracy was about 1 mile with bearing accuracy of 3 degrees.
US B4 IFF interrogation equipment with New Zealand design aerials was fitted with this outfit in
the radar truck which also incorporated plotting and communication facilities.
The third truck
contained power supply diesel generators and support spares and tools were
available with test gear.
ME4 Plan Position Indicator.
This New Zealand design equipment could be used with RN Type
271 or 272 equipment and provided two display units. a 9 CRT for local display and a similar unit to be fitted
on Bridge to provide information during passage. It is not clear whether a
transmitter and receiver were produce locally or the installation was used only
with the RN equipment. Calibration markers were
available. However after the end of hostilities this equipment removed from
four RNZN corvettes and two were was fitted mercantiles, These
were later modified. by removal of the existing cheese
type aerial which was replaced by a 4 feet paraboloid and by use of a more
powerful magnetron.
New
Zealand Radar under development in
August 1945
ME5 Plan Position Indicator.
Another
New Zealand panel for use with CD units.
Type ME2 (Fire Control Microwave Radar
Equipment.)
A prototype New Zealand design equipment gunnery use was also
developed during WW2 but this was never put into production, although the some
of equipment was in use for development trials for some months before the
project was cancelled
The aerial unit
included two four foot dishes with rotating dipoles for standard 10cm radar
transmitters and the receiver followed the practice of earlier NZ microwave
equipment but a more sophisticated ranging system had been under development which
included an expanded time base for accurate ranging.
Type ME3 Microwave Height Finding Radar
Unlike the ME2
equipment this was designed to accurately measure height of targets in
conjunction with Long Range Warning radar such as LRAW. However the development
programme for this purpose was cancelled in 1943 and it was not redesigned unit
1947 was adapted specifically for use in tracking of meteorological balloons.
A single paraboloid
aerial unit was used and the dipole unit could be moved both in azimuth and
elevation. Originally a 10cm magnetron was fitted with a standard
super-heterodyne receiver to provide display signals on two displays. One of
these was a 5 CRT for range measurement and the other a 9 CRT t show either
Elevation or Azimuth changes.
To meet the new
meteorological requirements some major changes were made to the transmitter and
receiver equipment with more significant alterations to the display outfits.
This equipment as modified for used fore several years.
Conclusions
The very considerable
design and development work carried out by the few New Zealand scientists available, resulted in many types of radar
equipment being in operational use in the Far East before similar equipment, such as fire control
for main armament of cruisers and suitable night time costal defence was
available in Europe or in North America. There work carried out under severe
restrictions due to lack of suitable components locally, without any
possibility of mass production and with no experience of the new techniques
being used in other countries was quite remarkable and has received little
recognition in either the UK or USA. The use of rack mounted equipment well in
advance of its introduction by the RN showed a clear understanding of the very important
need to provide easy access to equipment for repair and test as well as to
provide adequate documentation and test equipment for installation and support
whilst in operational use. The contribution they made is worthy of the cause
for which they made so many other contributions to the allied victory in 1945
References:
Appendix
No. 1 of the DSIR WW2 Narrative, "Technical description of radar sets".
"The Development of Radar in
New Zealand
in World War II by Unwin.
ADM220/1644, "Report of R.C.M. Trials, Tantallon, January-July 1944" in which an
NZ radar was used to represent a German radar.
Chapter
28 (on Radar) of the Official NZ WW2 History on "The Royal New Zealand Navy" by
Waters.
"Dr
Marsden and Admiral Halsey" by Galbreath describing the contribution of NZ radars and
scientists to the US Navy's Argus programme in the Pacific.
New
Zealand Scientists in Action: The Radio Development Laboratory and the Pacific
War" by Galbreath (overlaps with the previous paper).
The antecedents and subsequent
development of scientific radar in New Zealand by
GJ Fraser giving general background to the NZ WW2 radar programme.
