Jamming German Wurzburg RADAR with electronic countermeasures “Carpet” –Tactics, Equipment, & Impact

In WWII, the allies developed electronic RADAR countermeasures systems to combat the German FLAK threat. The active electronic countermeasures equipment is called “Carpet”. Both Barrage and spot jamming systems were incorporated into the bombers. By wars end 2 barrage jammers (AN/APT-2) were installed in all non – PFF bombers and several bombers from each group had spot Jammers (AN/APQ-9) installed. The jammers and chaff reduced bomber losses by 75% during blind bombing missions.

in this video we see RAF aircraft dropping chaff or window as part of their radar counter measures program in addition to chaff the RAF and US bombers will be equipped with electronic radar countermeasure systems the intent of this video is to review bomber radar jamming electronic equipment tactics and Effectiveness in disrupting both German early warning and gun laying radar this is the Channel’s fourth video deep diving topics related to German flak versus Allied bombers the other three videos are shown here and reside in the Channel’s Flack playlist so far we’ve covered German flak tactics chaff as a radar countermeasure and flak suppression by attack the eight tactics bombers can adopt to reduce flax Effectiveness are listed on this page from a Declassified 1945 ADI report titled German flak item D list counter measures to confuse or defeat enemy gun laying Radar Radar countermeasure systems adopted were either passive like chaff or active electronic Jammers like carpet Germany adopted a robust overlapping early warning radar system as shown on this map identifying Coastal radar stations and coverage as of June 1944 from a Declassified 1945 headquarters aeaf air staff document titled Operation Neptune as discussed in previous videos the Germans usually had ample warning of approaching bomber fleets characteristics of German radar systems are listed on this chart from a March 1945 air intelligence group document en titled Japanese Electronics The Columns represent the radar name size deployed height frequency range and use category the Freya and giant wburg Radars were used for air search early warning the small wburg were used for anti-aircraft Fire Control images of each of the German ground radar systems the Giant wburg and Paul Freya are adopted mainly as early warning Radars whereas a small wburg is used for flat gun laying radar this image shows a giant WSB B with an if antenna array located at the top of the radar the pole Freya with the lates consisting of transmitting receiving and I sections from an April 1945 war department document titled directory of German radar equipment images of the small wburg gun lay radar are shown two if antennas are located in the disc here characteristics of the small wburg are shown on this page the radar was designed in 1936 and used for anti-aircraft Fire Control search light control and ground control control of the Radar’s position is by manual hand wheeel crew inputs the disc is 10 ft in diameter practical range equated to 25 Mi when adopted for flag fire gun control additional specifications of the small wburg radar are listed on this page from a June 1945 Naval intelligence document titled German Aid to Japan first use was in 1942 the radar provides aircraft range elevation and asmith these parameters will be fed into the gun laying director the radar projects a beam at 17° the frequency can vary from 470 to 590 megacycles accuracy equates to 11 yards in range and 2° in Direction finding German radar technology lag behind the Allies has discussed on this page from an August 1945 headquarters air material command document titled where we stand at the end of the war the Germans were at the same state of radar technology as the allies were in 1942 they never thought microwave frequency was possible until inspection of salvaged radar systems from down us and British bombers they expended large resources in trying to mitigate the effects of Allied radar countermeasures the German radar mostly operated in the 50 cm wavelength and concluded shorter wavelengths to be impractical the Allies developed High Fidelity 3 cm radar this page describes electronic radar jamming from a February 1945 a assistant chief of the air staff intelligence report titled impact flak has a more detrimental effect on bomber Crews and Fighters both carpet and chaff reduce a flak Hazard these radar counter measures have reduced losses during blind bombing missions this image represents a blind bombing mission where Target sighing is by a Pathfinder bomber electronic jamming or carpet scrambles the radar return these Jammers are tuned to react with the German gun laying small wburg radar frequencies the Jammers are tuned to frequencies 1 me a cycle apart for best results even in clear weather carpet will reduce the effectiveness of the gun laying director in ranging as a German flak battery will need to rely solely on optical tracking up to 90% of the small wburg Radars are tuned to the 560 megacycle ban although the frequency could vary between 525 and 595 megacycles barrage jamming is like firing a shotgun covering a wide frequency band at low power while spot jamming targets a specific frequency at higher Powers advantages and disadvantages of radar spot jamming are discussed on this page from a 1992 Duke University Department of History dissertation titled the USAF and electronic warfare 1945 to 1955 all of the bombers radar countermeasures jamming power is concentrated on a specific frequency the jamming signal is likely stronger than the ground Radar’s reflected return this will blot out the radar screen spot jamming is limited to a small bandwidth of frequencies multiple spot jamming systems would be needed to react to All The Radars radar spot jamming systems require trained operators the wburg radar may switch frequencies a trained electronic countermeasures operator would need to adjust his equipment to account for any radar frequency change a barrage jamming system on the other hand sends a wideband with signal at a lower power actual radar frequency is not required but but a large strike force of ECM Jammers are needed to cover a large frequency band the bomber’s radio operator will need to turn the system on and off enough bombers are needed to cover the expected frequencies at sufficient power overlapping radar coverage is required a few missing frequencies may leave gaps in the radar coverage which would render the efforts wasted this chart illustrates the differences in coverage between spot and barrage jamming the scope return of an unjammed and jammed radar from a 194 5 office of scientific research and development document titled electronic warfare a report on radar countermeasures the bombers transmitter and blade antenna are shaded this video shows a b 29’s electronic countermeasures blade antennas this page lists bomber modifications that occurred throughout the war from a 1945 8th Army Air Forces evaluation board document titled tactical development all B24 and b7s except Pathfinders are to be equipped with two carpet barrage Jammers and 12 aircraft from each group to be equipped with spot Jammers a group is roughly 36 bombers field installations occurred in the spring and fall of 1944 this modification is required to jam German gun laying radar supply issues forc delays and modifications to this plan carpet equip bombers flew their first mission in October 1943 the losses for carpet equipped bombers were half that of those without carpet the the 15th Air Forces also deployed carpet equipped bombers chaff was first used in conjunction with carpet 2 months later in December 1943 carpet radar jamming systems were added to every bomber carpet and chaft proved to be very effective when used together this table list a US carpet Jammer designation and name frequency range spot jamming frequency width and power output from a 1988 Air Command and Staff College report titled electronic combat over the Third Reich electronic counter measures equipment naming convention is described with this example a an signifies Army and Navy the letter after the slash indicates the platform type where a is aircraft the next letter is the type of system where p is radar the next letter is a purpose of the equipment where T is transmitter and the last number is a series designator this page describes radar countermeasure jammers adopted by the eth Air Forces heavy bombers radar counter measures were expanded during the last part of 1944 by early 1945 electronic warfare was extensively used against German radar 75% of the eth Air Force’s bombers were fitted with two ap-2 barrage Jammers the frequency was preset prior to the mission based on updated weekly electronic intelligence intercepts bombers in each groups carried the AP q-9 carpet 3 spot Jammers and an ECM operator six spot Jammers could provide equivalent or better better results than 18 barrage Jammers The ap-2 Barrage Jammers were selected to jam wburg Radars initial shortage of the Jammers limited only one system to be installed on each bomber the system’s range was limited so all bombers needed to be transmitting to be effective specially equipped planes were used to monitor the wburg radar frequencies for tuning on the next missions large scale carpet counter measur started in October of 1944 when sufficient Jammers became available once enough Jammers were available two ap-2 BR Jammers were installed on each bomber this chart illustrates the frequencies of German ground radar and corresponding us carpet jamming ranges early warning Giant wsur and gun Ling small wsbg Radars operate in this range of frequencies the ap-2 carpet barrage Jammers can be tuned to this range and power settings and the AP q-9 in this frequ frequency range and power settings this page from a February 1945 air Technical Services command document titled graphic survey of radio and radar equipment outlines characteristics and components of the a a-2 Jammer the system is an aircraft platform radar transmitter barrage Jammer transmitter output frequency range is between 450 and 710 megacycles the frequency is preset prior to takeoff a bomber crew member will just need to turn the system on on and off it can be adapted as a spot Jammer however a trained ECM crew member will be needed to operate the system the effective range is 7 m from a giant wburg radar transmitter output Power Ranges from 4 to 8 watts the bombers will be field modified including two antenna mountings and a radar transmitter box each bomber was fitted with two systems a system weight equated to 60 lb this image illustrates The Barrage Jammer in action all bombers are equipped with barrage Jammers the Jammers disrupt the giant wburg early warning radar and gun laying radar this rare image shows the radar jamming antenna attached to a B17 this page outlines characteristics of the a apq -9 carpet 3 radar jammer the frequency range is between 475 and 585 megacycles it can be used as a barrage Jammer but is mostly used as a spot Jammer it can disrupt Giant wburg radar scope returns at a range of 6 miles the ECM operator changes jamming frequency by turning a dial noise signal power can vary from 10 to 20 watts the system includes a rectifier power unit radar transmitter and two antennas the system weight equates to 115 lbs the radar transmitter space dials gauges and switches radar electronic jamming Lessons Learned are listed on this page from a March 1945 15th Air Forces document titled fla attrition analysis complete German radar jamming can be obtained by the application of 30 to 35 ap-2 barrage Jammers and several spot Jammers or 16 to 18 AP q-9 in service as barrage Jammers plus several spot Jammers barrage Jammers cannot be tuned in the air and a single unjam frequency would render the bombers vulnerable with radar frequencies covered by barrage Jammers spot Jammers can increase protection by multiple factors but the barrage Jammers must completely saturate the radar frequencies ECM operators seek out and spot Jam enemy Radars operating outside of standard frequencies it would be impractical for spot jamming radar to fulfill the work of barrage jamming there should be a balanced distribution of both barrage and spot jamming equipment a good balance would be for each bomber group to have four spot Jammers assign a bomb group is roughly 36 airplanes so one out of every 9 Airplanes would be equipped with the apq -9 spot Jammer and carry an ECM operator the remaining 27 bombers would be fitted with two ap-2 barrage Jammers no extra crew members would be required for the barrage jamming equip bombers however the radio operator would be responsible for turning the Jammers on and off so how effective was radar jamming and reducing bomber Flack losses this can be addressed through several sources German Flack officers in Italy indicated that carpet rendered their wburg fir controlled Radars useless especially when shaft was also used in certain cases the radar counter measures were so effective no flat rounds were fired if they did fire the guns they resorted to barrage targeting which consumed large quantities of ammo and reduced the flax Effectiveness by an order of magnitude as compared to continuously pointed fire an Air Force memo stated that radar counter measures were as critical to the bomber against flag as their guns are to Fighters RCM equipment was to travel to England by the fastest vessel possible this page outlines post-war interrogation interviews regarding the effectiveness of radar countermeasures against flak batteries from a 1945 document titled German flak radar jamming became significant in October of 1944 chaff was an issue in October 43 but was overcome somewhat active jamming with carpet rendered radar returns useless if the radar could not direct the flat guns no firing occurred the Germans could detect the presence of jamming equipment at ranges of 15 to 21 kilm from the small wburg sets radar counter measures were extremely effective as discussed on this 1945 headquarters United States Air Force and Europe document titled minutes of flat conference Chap and carpet rendered unseen continuously pointed fire inaccurate or impossible even in clear conditions radar cannot be used to measure the bombers formation ranges radar counter measures necessitated flat Gunners to switch to barrage fire which is one1 the accuracy of continuously pointed fire during the last 6 to 8 months of the war the intensity of bomber radar counter measures was so effective the Germans believed the radar Battle was over chaff radar scope noise was too high for any returns and the electronic carpet counter measures forced wburg Radars to operate at their limits General opin I is that chaff was more effective than carpet both were detrimental to radar operations even on clear days post-war interrogations of German Flack Personnel leads to this conclusion radar counter measures reduced wburg controlled gun laying radar by 75% this equates to a savings of 450 bombers in summary Germany was 2 years behind the Allies in radar technology electronic radar jamming carpet was adopted by heavy bombers in addition to dispensing chaff these systems were as critical to combating fla flak as bomber Gunners were in combating Fighters by the war’s end the bombers were fitted with two ap-2 barrage Jammers and some of the group’s bombers were fitted with the AP q-9 spot Jammers plus an electronic countermeasures operator the radar countermeasure systems of both carpet and chaff are responsible for flak bomber loss reduction of 75% when the gun were radar directed this equated to a savings of around 450 bombers did any of the data surprise you if you’ve enjoyed this radar jamming presentation Deep dive please consider engaging with the video by commenting liking Andor subscribing to the Channel World War II us bombers