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  World War 2 at Sea

NEW ZEALAND RADAR DEVELOPMENT

by Geoffrey B Mason, Lieutenant Commander, RN (Rtd) (c) 2007

Radar fit on cruiser HMNZS Leander later in World War 2.
See ship photo below for enlargement (Navy Photos)
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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.

 

  

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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.

 

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