IF and associated interface requirements applicable to Satellite Communications SATCOM Earth Terminals ET operating over military X-band and Ka-band Super High Frequency SHF channels. Military unique requirements for ET that may operate over commercial C-band, Ku-band, and Ka-band are included. Equipment developers may exceed the requirements herein to satisfy specific program requirements, provided that interoperability is maintained. Thus, incorporating additional standard and nonstandard capabilities and interfaces is not precluded. Existing SHF SATCOM terminals need not conform to this MIL-STD unless they undergo a modernization program.

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MIL-STD-188-164B

4.4.2 Antenna polarization, transmit. The antenna shall be capable of transmitting right-hand (clockwise) circular polarization (RHCP) and left-hand (counterclockwise) circular polarization (LHCP). However, military Ka-band terminals do not have to operate simultaneously with right-hand and left-hand circular polarizations.

4.4.3 Antenna axial ratio, transmit. The military Ka-band transmit axial ratio shall be no greater than 1.0 dB.

4.4.4 Antenna polarization, downlink, receive. The

antennas for military Ka-band terminal types shall be capable of receiving left-hand (counter-clockwise) and right-hand (clockwise) circular polarization (RHCP). However, military Ka- band terminals do not have to operate simultaneously with right- hand and left-hand circular polarizations.

4.4.5 Antenna axial ratio, receive. The military Ka- band receive axial ratio shall be no greater than 1.5 dB.

4.5 Military X-band antenna requirements.

4.5.1 Antenna sidelobe levels and transmit EIRP Spectral Density (ESD). The antenna sidelobe and ESD requirements are described in a and b (below):

a. De/A � 50. The gain of the antenna in the GSO plane, including radome effects, shall be such that at least 90% of the sidelobe peaks do not exceed the mask given below and no individual peak exceeds the mask by more than 3dB.

where

G(0) = 29-25 log10 0 (dBi) for 1° or 100 A/De ° (whichever is larger, up to 2°) � 0 < 20°

G(0) = -3.5 (dBi) for 20° � 0 � 26.3°

G(0) = 32-25 log10 0 (dBi), for 26.3° < 0 < 48°

G(0) = -10 (dBi), for 48° � 0 � 180°

G = gain relative to an isotropic antenna

0 = off-axis angle in the direction of the satellite