Gun precision / dispersion

[fsimon]

Dave,
Peilverfahren A/N is lobe switching / Radattlepeilung, i.e. lobe on receive only?
And phase shift measurement did not require the Radattelpeilung anymore?
And would that mean, that the whole of the antenna could be used for the measurement with no reduction in tracking range?
Do I understand you correct or am I mixing things up?
And Bismarck had FuMG 40 not 39?
Was 2000Hz vs 500Hz the discriminator or something else?
Herr Nilsson has indicated, that Bismarck was equipped with 2000Hz devices and TS1 transmitters on 2 of its sets and most likely TS6 on the top set.

Best regards
Frank

[Dave Saxton]

I understand, that the earlier 2x4m antenna was not common mode. I understand that the 3x6m antenna was common mode and horizontaly polarized. I was wondering about the 2 x 6m antenna on Scharnhorst's aft mount and Scheer and Lützow, since the 2x6m antenna appeared at around the same time as the large 3x6m antenna.
Best regards
Frank

The 2x6 m antennas were common mode.

[fsimon]

The 2x6 m antennas were common mode.

Oh, wow!
That would mean an increase from 10 tranmitting dipoles on 2x4m antenna to 32 transmitting dipoles.
And an increase from 10 receiving dipoles to 32 receiving dipoles.
This would mean an effective range increase of 33% and give the 2x6m antenna a range vs. battleships of 40km.
The increase from 10 dipoles to 64 dipoles would give an increase of 59% and give the 3x6m antenna a range vs. battleships of 48km.
All this based on an average range of 30km vs. battleships with the 2x4m antenna.

[Dave Saxton]

Dave,
Peilverfahren A/N is lobe switching / Radattlepeilung, i.e. lobe on receive only?
And phase shift measurement did not require the Radattelpeilung anymore?
Do I understand you correct or am I mixing things up?
And Bismarck had FuMG 40 not 39?
Was 2000Hz vs 500Hz the discriminator or something else?
Herr Nilsson has indicated, that Bismarck was equipped with 2000Hz devices and TS1 transmitters on 2 of its sets and most likely TS6 on the top set.

Best regards
Frank

PV A/N switches transmitted lobes.
RP only measures the received signal so it is LORO in a general sense. LORO would be kind of a mis discription, though. Technically there is no lobe switching. It just measures within the received beam with no reduction of antenna gain.
The phase shift is measured by RP.

The AKVS report says that problems were encountered utilizing the fine bearing features in the aft installation, so that would indicate that it was more than the foretop installation.

Bekker (IIRC) reported in the early 90s that Bismarck's radars tested with a max output of 14kw. I think that would impossible with TS1 sets. I could be wrong. There's just a lot we don't know.

Did Bismarck have a FuMG 39 aft and used the A/N type of lobe switching? What about the conning tower installation?
If Bismarck had only the more modern set at the foretop, was it the one which was knocked out? That could explain some things. It could also raise more questions.

Why would they install older sets a year after they were superseded?

[Dave Saxton]

The 2x6 m antennas were common mode.

Oh, wow!
That would mean an increase from 10 tranmitting dipoles on 2x4m antenna to 32 transmitting dipoles.
And an increase from 10 receiving dipoles to 32 receiving dipoles.
This would mean an effective range increase of 33% and give the 2x6m antenna a range vs. battleships of 40km.
The increase from 10 dipoles to 64 dipoles would give an increase of 59% and give the 3x6m antenna a range vs. battleships of 48km.
All this based on an average range of 30km vs. battleships with the 2x4m antenna.

I don't know how proportional the relationship; range per antenna gain is. I know in the documents, the German radar engineers reported a 30% increase in range attainment from the larger common mode antennas. Confirmed by trials. However, a very effective way to increase antenna gain is to reduce the wavelength. But reduced wavelength requires more power to attain a given range- other factors remaining the same. (I need to look up what Callick wrote on this.)

It is well established that it takes a 16 fold increase in power to attain a doubling of range-all other factors remaining the same. So increasing antenna gain is a good way to go. Plus increased antenna gain improves bearing resolution. Increasing gain and power being a better way to go.

[fsimon]

Thank you Dave,
I understand Radattelpeilung is angle measurement via phase shift and does not reduce the antenna gain on transmission, but what about a reduction in gain on reception?
Here is this document, Thorsten once provided, iirc, and it states that range is reduced to about 2/3 when using Seitenzusatz.

Meßgenauigkeit.JPG (129.52 KiB) Viewed 8320 times

[Dave Saxton]

Is that RP or A/N?

[fsimon]

I don't know how proportional the relationship; range per antenna gain is. I know in the documents, the German radar engineers reported a 30% increase in range attainment from the larger common mode antennas. Confirmed by trials. However, a very effective way to increase antenna gain is to reduce the wavelength. But reduced wavelength requires more power to attain a given range- other factors remaining the same. (I need to look up what Callick wrote on this.)

It is well established that it takes a 16 fold increase in power to attain a doubling of range-all other factors remaining the same. So increasing antenna gain is a good way to go. Plus increased antenna gain improves bearing resolution. Increasing gain and power being a better way to go.

Doubling the gain is the same as doubling the power, I think.
So, if you increase gain or power, if you will, by 1.6 you increase range by the fourth root, i.e. 1.124, with other words an increase by 12%. This is what I presumed so far, thinking, that the 2x6m antenna was not using common mode.
With common mode, i.e. 32 transmitting and receiving dipoles, gain increses by 3.2. Fourth root of 3.2 is 1.337, i.e. an increase by 33%. So this is in line with the reported 30% increase in range by the German radar engineers.
An increase by 6.4 for the 3x6m antenna would mean (fourth root of 6.4 is 1.59) an increase of 59%.

[fsimon]

Is that RP or A/N?

I do not know. There is no date in conjunction with the page. I am hoping, that Thorsten could help with that.

[fsimon]

Common mode for the 2 x 6m antenna with 2 x 16 dipoles would explain how the battery "Großer Kurfürst" could shoot blind fire out to 33km like Thorsten posted earlier. In June 1941 "Großer Kurfürst" would have had a "Calais B" 2 x 6m antenna. In early 1941 Gneisenau spotted single 28cm splash clearly at 16km using its 2x4m TS1 (2kW) device.
Increase to TS6 (8kW) gives range increase by 41% (factor 1.414 (fourth root of 4). =>16 x 1.41= 22.63km
Increase from 10 to 32 dipoles (fourth root of 3.2 = 1.337) = 22.63 x 1.337 = 30.26km
Now it starts making sense to me.
Thank you guys.

[fsimon]

Dave,
would the 2 x 4m FuMG 40 (FuMO 26 and 27) also have had common mode then?
Frank

[fsimon]

Thorsten earlier provided a report, in which Prinz Eugen tracked a destroyer outside of 30km in June 1944 so with the large 3x6m commen mode antenna.
Tracking range vs. destroyer with the old battleship radar was 20km and 30km only vs. battleships.
If I bring this into relation, it would mean that Prinz Eugen could expect 45km vs. battleships with the 3x6m common mode antenna, which would be in line with the earlier calculation.

"... increase from 10 tranmitting dipoles on 2x4m antenna to 32 transmitting dipoles.
And an increase from 10 receiving dipoles to 32 receiving dipoles.
This would mean an effective range increase of 33% and give the 2x6m antenna a range vs. battleships of 40km.
The increase from 10 dipoles to 64 dipoles would give an increase of 59% and give the 3x6m antenna a range vs. battleships of 48km.
All this based on an average range of 30km vs. battleships with the 2x4m antenna."

While 48km would be below the horizon and 45km would be the maximum with 30m antenna height and 30m target height.
My math is probably ridiculous, but it seems to make some sense and fits the reports.

[fsimon]

Common mode for the 2 x 6m antenna with 2 x 16 dipoles would explain how the battery "Großer Kurfürst" could shoot blind fire out to 33km like Thorsten posted earlier. In June 1941 "Großer Kurfürst" would have had a "Calais B" 2 x 6m antenna. In early 1941 Gneisenau spotted single 28cm splash clearly at 16km using its 2x4m TS1 (2kW) device.
Increase to TS6 (8kW) gives range increase by 41% (factor 1.414 (fourth root of 4). =>16 x 1.41= 22.63km
Increase from 10 to 32 dipoles (fourth root of 3.2 = 1.337) = 22.63 x 1.337 = 30.26km
Now it starts making sense to me.
Thank you guys.

On the other hand does an increase from 2kW to 8kW in peak power not necessarily mean the same increase in effective radiated power...anyone, please help!

[Thorsten Wahl]

Is that RP or A/N?

Radattel half phase shift by lambda/2

[fsimon]

Thorsten thank you.
I understand that the Radattelpeilung was the Minimumpeilung (differnet from A/N Peilung, also called Vergleichspeilung, lobe switching with two beams) and it used a diffential diagramm for accurate angle measurement via phase shift, but for tracking and range measurement the sum was still available and therefore no loss in maximum range, i.e no loss in antenna gain.
How come this report states only 2/3 of the otherwise attainable range?