Thank you Chizh. I understand therefore, that the APP-46TD is an optional piece of equipment, and that even if the R-40TD is capable of radio-correction, in practice this feature is not used. Correct?

I have some new questions, but I have a problem with my password and cannot start a new subject.

1. The MiG-23 and MiG-25 radar experienced many updates:

Sapfir-23
Sapfir-23D
Sapfir-23D-III
Sapfir-23ML
Sapfir-23MLA Ametist

Smerch-A
Smerch-A2
Smerch-A3
Sapfir-25

Did any of these variants feature a coherent gridded travelling-wave-tube (TWT or GTWT) amplifier for pulse-doppler detection of targets on background on the earth?

Consider the contradicting information:

'импульсно-доплеровская РЛС "Сапфир-23Д"'
http://airbase.uka.ru/hangar/russia/...23/index.phtml

and:

'В качестве основы решения был выбран метод селекции движущихся целей (СДЦ) с применением внешней когерентности сигналов, отраженных от земной поверхности и движущейся цели... Для реализации этого решения НИИ радиостроения была задана разработка БРЛС "Сапфир-23" для самолета МиГ-23'
http://195.222.131.14:81/003/03/real_BRLS.htm

The first reference says the MiG-23 radar was pulse-doppler. The second radar says it used an envelope beat-detection method. Which is true?

2. Does anyone know why Russian phased array radars appear to lack a guard horn for removing sidelobe signals? Consider the F-15 radar antenna:

http://212.67.202.161/~steved/Pages/f15e13jpgpage.htm

At the top and bottom of the circular array, you can see tiny rectangular openings for waveguide horn antennas. These small antennas have a broad pattern that is more sensitive that the main array's sidelobes, but less sensitive than its main beam. By comparing signals received through both the array and the guard horn, the radar can tell if a signal came from the main beam or the sidelobe, and reject sidelobe ground clutter. I don't see this feature on any of the modern Russian arrays:

http://airbase.uka.ru/airshows/maks/...g/DSCN2304.htm

How do modern Russian radars deal with false signals received on the antenna sidelobes? If this question is not clear I can try to explain it better.

Thank you for your time!

-SK