The HSB antennas differ from the BWG antennas in that the optics design is slightly different and the subreflector does not focus automatically for the purpose of maintaining gain as the elevation angle of the antenna changes. The HSB antennas have higher tracking rates than do the BWG antennas, thus they are the appropriate antennas to use when tracking earth-orbiting satellites.
Those antennas with two LNAs at a particular frequency (S-band or X-band) will be capable of receiving simultaneous RCP and LCP downlink signals. Not all antennas will have two LNAs installed for the same frequency band. If an uplink capability exists at a particular frequency, the antenna will be capable of transmitting through the diplexer in one polarization and receiving in the low-noise (non-diplexed) path with the opposite polarization. If uplink and downlink are at the same polarization, then reception must be through the diplexed path, with subsequent higher noise and lower gain. Typically the following modes are available for transmission and reception:
The receiving frequency bands are S-band (2200-2300 MHz), X-band (8400-8500 MHz), and Ka-band (31800-32300 MHz).
Table 1. Geographic Locations of BWG and HSB Antennas
Antenna Location Longitude Latitude Height, MSL (Deg.) (Deg.) (m)
BWG Antennas DSS 24 Goldstone W 116.9 N 35.3 956 DSS 25 Goldstone W 116.9 N 35.3 971 DSS 26 Goldstone W 116.9 N 35.3 981 DSS 34 Canberra E 149.0 S 35.4 672 DSS 54 Madrid W 004.2 N 40.4 787 HSB Antennas DSS 27 Goldstone W 116.8 N 35.2 1050 DSS 28 Goldstone W 116.8 N 35.2 1050
Table 2. Operational Schedule for BWG and HSB Antennas
Table 3. BWG and HSB Antenna Configurations
Antenna Band- S-Up S-Down X-Up X-Down Ka-Down Ka-Up Up/Down Power(1) LNA-1 LNA-2 Power LNA-1 LNA-2 LNA Power
DSS 24 BWG S-Up/Down 20 kW HEMT(2) N/A N/A Maser N/A N/A N/A Goldstone X-Down DSS 25 BWG X-Up/Down N/A N/A N/A 4 kW Maser HEMT(2) HEMT(3) 800 W(4) Goldstone Ka-Up/Down DSS 26 BWG X-Up/Down N/A N/A N/A 4 kW HEMT(2) HEMT(2) N/A N/A Goldstone DSS 34 BWG S-Up/Down 20 kW HEMT(2) N/A 4 kW HEMT(2) N/A N/A N/A Canberra X-Up/Down DSS 54 BWG S-Up/Down 20 kW HEMT(2) N/A 4 kW Maser N/A N/A N/A Madrid X-Up/Down DSS 27 HSB S-Up/Down 200 W HEMT(5) N/A N/A N/A N/A N/A N/A Goldstone DSS 28 HSB X-Up/Down N/A N/A N/A TBD Maser N/A N/A N/A Goldstone
NOTES: 1. Transmitter power refers to nominal power available at transmitter output. Exact powers are given in Table 5. S-band uplink is limited to 5 kW transmitter power in the frequency range 2070-2090 MHz. 2. All BWG antennas use cooled HEMTs. 3. Cooled HEMT utilizing cooled feed with aperture load. 4. Uses Ka/Ka dichroic plate as diplexer. 5. DSS 27 HSB uses room temperature S-band HEMT.
Figure 2. DSS 25 BWG (Goldstone) Functional Block Diagram
Figure 3. DSS 26 BWG (Goldstone) Functional Block Diagram
Figure 4. DSS 34 BWG (Canberra) Functional Block Diagram
Figure 5. DSS 54 BWG (Madrid) Functional Block Diagram
Figure 6. DSS 27 HSB (Goldstone) Functional Block Diagram
Figure 7. DSS 28 HSB (Goldstone) Functional Block Diagram
Table 4a presents the expected noise temperatures of operational LNAs used in the BWG and HSB antennas and Table 4b presents the nominal noise temperature values used in modeling. It can be seen from these tables that the nominal noise temperature values used in performance modeling (see Section 2.6.6) may vary significantly from the actual value of an operational LNA.
Table 4a. Operational LNA Input Noise Temperatures
Table 4b. LNA Noise Temperatures Used in Modeling
Band Type LNA & Model Minimum(K) Maximum(K)
BWG Antennas S-Band HEMT, S2 4.5 7.0 X-Band TWM/CCR, BLK IIA 3.0 5.0 HEMT, X1 7.0 15.0 HEMT, X2 5.0 6.5 HEMT, X3 4.0 5.0 Ka-Band HEMT 28.0 (at feedhorn aperture, 10/98) 21.0 (at feedhorn aperture, 5/01) HSB Antennas S-Band HEMT, room temp. 25.0 45.0 X-Band TWM/CCR, BLK I 4.0 9.0
Band Type LNA Nominal Temperature(K)
BWG Antennas S-band Cooled HEMT 5.7 (at LNA input) X-band BLK II-A Maser 3.43 (at LNA input) X-band Cooled HEMT 9.7 (at LNA input) Ka-band Cooled HEMT and Feed 28.0 (at feedhorn aperture) HSB Antennas S-band Room Temperature HEMT 45.0 (at LNA input) X-band BLK I Maser 4.5 (at LNA input)
Table 5a. Uplink Performance Characteristics for BWG Antennas
Table 5b. Uplink Performance Characteristics for HSB Antennas
Parameter DSS 24 DSS 25 DSS 26 DSS 34 DSS 54 S-band X-band Ka-band X-band S-band X-band S-band X-band
Gain at horn aperture (dBi) 56.12 66.92 78.01 66.92 56.14 66.92 56.14 66.92 @ 45-Deg. Elevation Power at horn aperture (W) 16991 3565 TBD 3565 16991 3565 16991 3565 Power at horn aperture (dBm) 72.30 65.52 TBD 65.52 72.30 65.52 72.30 65.52 EIRP at horn aperture (dBm) 128.43 132.44 TBD 132.44 128.44 132.44 128.44 132.44 Gain Falloff (dB) -0.01 -0.04 -0.64 -0.04 -0.01 -0.04 -0.01 -0.04 @ 10 and 80 Deg. Elevation EIRP @ aperture (dBm) 128.42 132.40 TBD 132.40 128.43 132.40 128.43 132.40 @ 10 and 80 Deg. Elevation
Note: S-band uplink is limited to 5 kW transmitter power in the frequency range 2070-2090 MHz.
Parameter DSS 27 DSS 28 S-band X-band
Gain at horn aperture (dBi) 54.36 66.76 @ 45-Deg. Elevation Power at horn aperture (W) 170 TBD Power at horn aperture (dBm) 52.30 TBD EIRP at horn aperture (dBm) 106.67 TBD Gain Falloff (dB) -0.01 -0.04 @ 10 and 80 Deg. Elevation EIRP @ aperture (dBm) 106.66 TBD @ 10 and 80 Deg. Elevation
GAIN S-band: favorable tolerance, +0.1 dB adverse tolerance, -0.2 dB triangular PDF X-band: favorable tolerance, +0.1 dB adverse tolerance, -0.2 dB triangular PDF Ka-band: favorable tolerance, +0.2 dB adverse tolerance, -0.4 dB triangular PDF NOISE TEMPERATURE S-band: favorable tolerance, -1.0 K adverse tolerance, +2.0 K triangular PDF X-band: favorable tolerance, -1.0 K adverse tolerance, +2.0 K triangular PDF Ka-band: favorable tolerance, -1.0 K adverse tolerance, +2.0 K triangular PDF
A triangular PDF (probability density function) implies that there is no chance the gain or noise temperature will be found outside of the limits indicated.
Gain and noise temperature values presented in tables or calculated by use of equations should be considered to be design values, or design expectations. For a triangular distribution, the mean (M) and variance (V) of the distribution can be calculated from the design value (D) and the favorable (F) and adverse (A) tolerances by:
M = D + (F+A)/3
2.6.1 Gain (DSS 24 BWG Antenna) - Figures 8 and 9 show DSS 24 (Goldstone) gain performance (referenced to the LNA input), based on measurements, for a vacuum condition (no atmosphere) and with additional atmospheric losses for various weather conditions as given in module TCI-40, Atmospherics, of this handbook. Because weather effects at S-band do not change significantly from 0% (minimum effect) to 90% (exceeded 10% of the time), the gain (and noise temperature) curves for 0%, 25%, 50%, 80%, and 90% lie nearly on top of one another. At X-band, the weather effects are somewhat more spread out, which results in distinct weather-effect curves.
Figure 8. DSS 24 (Goldstone) Measured S-band Gain; S/X Mode, Non-diplexed
Figure 9. DSS 24 (Goldstone) Measured X-band Gain; S/X Mode, Non-diplexed
For S-band (Figure 8), in the S/X, non-diplexed mode, with the S/X dichroic plate over the S-band horn, the DSS 24 vacuum gain as a function of elevation angle (el, degrees) is given by:
dBi Notes 1. Peak vacuum gain occurs at 90-degrees elevation angle. 2. For the S/X diplexed mode, subtract 0.10 dB.
S-band is always received with the S/X dichroic plate over the S-band horn. This is called the S/X mode. There is no S-band solid plate reflector; so there is no higher-gain configuration available for S-band.
For X-band (Figure 9), in the S/X-mode, with the S/X dichroic plate in place and a flat plate over the X-band horn, non-diplexed, the DSS 24 vacuum gain is given by:
dBi Note: For the X-only mode, with the S/X dichroic plate retracted, add 0.05 dB.
There is no X-band uplink at DSS 24, thus there is no diplexed mode available.
Table 6a shows measured DSS 24 antenna gain (referenced to the LNA input) at various elevation angles for Goldstone average clear weather (CD=0.25) as given in module TCI-40, Atmospherics, of this handbook.
Table 6a. DSS 24 (Goldstone) Measured Antenna Gain with 25% Average Clear Weather
Band-MHz Mode Diplex LNA Elevation (deg.) 90 80 60 45 30 20 15 10
S - 2295 S/X No HEMT 56.77 56.77 56.74 56.69 56.63 56.56 56.51 56.43 S/X Yes HEMT 56.67 56.67 56.64 56.59 56.53 56.46 56.41 56.33 X - 8420 X-Only No maser 68.03 68.05 68.07 68.06 68.03 67.98 67.94 67.86 S/X No maser 67.98 68.00 68.02 68.01 67.98 67.93 67.89 67.81
2.6.2 Gain (DSS 25, 26, 34, 54 BWG Antennas) - For all other BWG antennas, the following modeled vacuum gains apply, assuming a main reflector panel setting of 0.25 mm at DSS 25 and 0.50 mm at DSS 26, 34, and 54:
S-band: dBi (DSS 34, 54) X-band: dBi (DSS 25) X-band: dBi (DSS 26, 34, 54) Ka-band: dBi (DSS 25)
The S- and X-band coefficients of the elevation terms are modeled by frequency-squared from the Ka-band coefficient of 0.00052.
The following configurations apply to the above equations:
S-band: S/X mode (S/X dichroic in place), non-diplexed, LNA-1 path (DSS 34, 54) X-band: X-only mode (S/X dichroic retracted), non-diplexed, LNA-1 path (DSS 25, 26, 34, 54) Ka-band: Ka-only (X/Ka dichroic retracted), non-diplexed, LNA-1 path (DSS 25)
Figure 10 shows the modeled Ka-band gain performance for DSS 25 (Goldstone) referenced to the feed aperture for a vacuum condition (no atmosphere) and with additional atmospheric losses for various weather conditions. This figure assumes a main reflector panel setting of 0.25 mm, rms and illustrates the additional effects of weather for Ka-band when compared to the lower frequency bands.
Figure 10. DSS 25 (Goldstone) Modeled Ka-band Gain; Ka-only Mode, Non-diplexed
Table 6b shows gain values as a function of elevation angle, for 25% CD average-clear weather, as given in module TCI-40, Atmospherics, of this handbook, for all frequencies and configurations of the other BWG antennas. At S- and X-bands, the gain is referenced to the LNA input; at Ka-band it is referenced to the feedhorn aperture.
Table 6b. BWG Modeled Antenna Gains with 25% Average Clear Weather
DSS 25 (Goldstone)
Band-MHz Mode Diplex LNA Elevation (deg.) 90 80 60 45 30 20 15 10
X - 8420 X-Only No maser 68.12 68.15 68.18 68.18 68.15 68.11 68.06 67.98 X-Only No HEMT 68.05 68.08 68.11 68.11 68.08 68.04 67.99 67.91 X-Only Yes maser 67.95 67.98 68.01 68.01 67.98 67.94 67.89 67.81 X-Only Yes HEMT 67.88 67.91 67.94 67.94 67.91 67.87 67.82 67.74 X/Ka No maser 68.11 68.14 68.17 68.17 68.14 68.10 68.05 67.97 X/Ka No HEMT 68.04 68.07 68.10 68.10 68.07 68.03 67.98 67.90 X/Ka Yes maser 67.94 67.97 68.00 68.00 67.97 67.93 67.88 67.80 X/Ka Yes HEMT 67.87 67.90 67.93 67.93 67.90 67.86 67.81 67.73 Ka - 32000 Ka-Only No HEMT 77.63 78.05 78.55 78.64 78.45 78.14 77.89 77.50 Ka-Only Yes HEMT 77.53 77.95 78.45 78.54 78.35 78.04 77.79 77.40 X/Ka No HEMT 77.57 77.99 78.49 78.58 78.39 78.08 77.83 77.44 X/Ka Yes HEMT 77.47 77.89 78.39 78.48 78.29 77.98 77.73 77.34DSS 26 (Goldstone)
X - 8420 X-Only No HEMT-1 68.03 68.06 68.09 68.09 68.06 68.02 67.97 67.89 X-Only No HEMT-2 67.96 67.99 68.02 68.02 67.99 67.95 67.90 67.82 X-Only Yes HEMT-1 67.86 67.89 67.92 67.92 67.89 67.85 67.80 67.72 X-Only Yes HEMT-2 67.79 67.82 67.85 67.85 67.82 67.78 67.73 67.65DSS 34 (Canberra)
S - 2295 S/X No HEMT 56.71 56.71 56.71 56.70 56.68 56.64 56.62 56.56 S/X Yes HEMT 56.61 56.61 56.61 56.60 56.58 56.54 56.52 56.46 X - 8420 X-Only No HEMT 68.02 68.05 68.08 68.08 68.05 68.00 67.95 67.85 X-Only Yes HEMT 67.85 67.88 67.91 67.91 67.88 67.83 67.78 67.68 S/X No HEMT 67.97 68.00 68.03 68.03 68.00 67.95 67.90 67.80 S/X Yes HEMT 67.80 67.83 67.86 67.86 67.83 67.78 67.73 67.63DSS 54 (Madrid)
S - 2295 S/X No HEMT 56.71 56.71 56.71 56.70 56.68 56.64 56.62 56.56 S/X Yes HEMT 56.61 56.61 56.61 56.60 56.58 56.54 56.52 56.46 X - 8420 X-Only No maser 68.02 68.05 68.08 68.08 68.05 68.00 67.95 67.85 X-Only Yes maser 67.85 67.88 67.91 67.91 67.88 67.83 67.78 67.68 S/X No maser 67.97 68.00 68.03 68.03 68.00 67.95 67.90 67.80 S/X Yes maser 67.80 67.83 67.86 67.86 67.83 67.78 67.73 67.63
The X-only mode for all antennas implies that there is a solid (flat) reflector over the X-band horn. For an X-only antenna (DSS 26), this is the normal configuration. For an S/X antenna (DSS 24, 34, and 54), this implies that the S/X dichroic plate is retracted. For an X/Ka antenna (DSS 25), and possibly future S/X/Ka antennas, X-only implies an optimum performance configuration for X-band in which the X/Ka dichroic is replaced by a solid plate. Use of an X/Ka dichroic over the X-band horn (rather than a flat plate) will reduce the X-band gain by 0.01 dB as shown for DSS 25 in Table 6b.
For Ka-band gain in the X/Ka-mode, with an X/Ka dichroic in the microwave path, subtract 0.06 dB from the Ka-only gain values. For a diplexed mode, using a Ka/Ka dichroic plate as the diplexer, subtract 0.10 dB from the non-diplexed gain values.
2.6.3 Gain (DSS 27, 28 HSB Antennas) - Figure 11 shows the DSS 27 (Goldstone) gain performance (referenced to the LNA input) at S band, based on measurements, for a vacuum condition (no atmosphere) and with additional atmospheric losses for various weather conditions as given in module TCI-40, Atmospherics, of this handbook.
Figure 11. DSS 27 (Goldstone) Measured S-band Gain; S-only Mode, Diplexed
The equation for the elevation component of gain in this figure is:
Gvac(el) = 55.06 - 0.00205 (90-el) dBi Note: Peak vacuum gain occurs at 90-degrees elevation angle.
The S-band gain for the DSS 27 HSB antenna as a function of elevation angle with 25% CD average-clear weather, as given in module TCI-40, Atmospherics, of this handbook is shown in Table 7. DSS 27 operates only in an S-band diplexed configuration.
Table 7. DSS 27 (Goldstone) Measured S-band Antenna Gain with 25% Average Clear Weather
Band-MHz Mode Diplex LNA Elevation (deg.) 90 80 60 45 30 20 15 10
S - 2295 S-Only Yes HEMT 55.04 55.01 54.97 54.93 54.88 54.84 54.80 54.73
Figure 12 shows the modeled DSS 28 (Goldstone) gain performance (referenced to the LNA input) at X-band for a vacuum condition (no atmosphere) and with additional atmospheric losses for various weather conditions as given in module TCI-40, Atmospherics, of this handbook.
Figure 12. DSS 28 (Goldstone) Modeled X-band Gain; X-only Mode, Non-diplexed
The equation for the elevation component of gain in this figure is:
dBi
The X-band gain for the DSS 28 HSB antenna as a function of elevation angle with 25% CD average-clear weather, as given in module TCI-40, Atmospherics, of this handbook, in the non-diplexed and diplexed configurations is shown in Table 8.
Table 8. DSS 28 (Goldstone) Modeled X-band Antenna Gain with 25% Average Clear Weather
Band-MHz Mode Diplex LNA Elevation (deg.) 90 80 60 45 30 20 15 10
X - 8420 X-Only No maser 67.68 67.79 67.92 67.94 67.89 67.80 67.73 67.62 X-Only Yes maser 67.51 67.62 67.75 67.77 67.72 67.63 67.56 67.45
2.6.4 Atmosphere Adjustment to Vacuum Gain - To account for atmospheric effects on net gain for all antennas, attenuation at the elevation angle (el) of interest should be subtracted from the vacuum gains as given above.
attenuation(el) = dB where = zenith atmospheric attenuation as given in 810-5, TCI-40, for the appropriate antenna location, frequency, and weather cumulative distribution (CD).
Thus, the net effective antenna gain G(el) is given by
dBi
2.6.5 Noise Temperature (DSS 24) - Figures 13 and 14 show DSS 24 (Goldstone) noise temperature performance based on measurements, for a vacuum condition and with additional noise contributions for various weather conditions as given in module TCI-40, Atmospherics, of this handbook. The S-band performance (Figure 13) is for the non-diplexed S/X mode whereas the X-band performance (Figure 14) is for the X-only mode with the S/X Dichroic Plate retracted.
Figure 13. DSS 24 (Goldstone) Measured S-band Noise Temperature; S/X Mode, Non-diplexed
The curve for S-band vacuum-condition noise temperature as a function of elevation angle (Figure 13) is given by:
K
A measured value of 6.45 K must be added to the non-diplexed value to get the diplexed performance.
Figure 14. DSS 24 (Goldstone) Measured X-band Noise Temperature; X-only Mode, Non-diplexed
The curve for X-band vacuum-condition noise temperature (Figure 14) is flat and is given by
K
For the non-diplexed S/X mode, with the S/X dichroic plate in place, add 1.4 K (based on measurements). There is no X-band uplink at DSS 24, thus there is no diplexed mode.
Table 9a shows measured DSS 24 antenna noise temperature (referenced to the LNA input) at various elevation angles for Goldstone average clear weather (CD=0.25) as given in module TCI-40, Atmospherics, of this handbook.
Table 9a. DSS 24 (Goldstone) Measured Operating Noise Temperature with 25% Average Clear Weather
Band-MHz Mode Diplex LNA Elevation (deg.) 90 80 60 45 30 20 15 10
S - 2295 S/X No HEMT 30.20 30.26 30.67 31.41 33.05 35.41 37.60 41.62 S/X Yes HEMT 36.65 36.71 37.12 37.86 39.50 41.86 44.05 48.07 X - 8420 X-Only No maser 25.35 25.38 25.68 26.24 27.49 29.46 31.46 35.47 S/X No maser 26.75 26.78 27.08 27.64 28.89 30.86 32.86 36.87
2.6.6 Noise Temperature (DSS 25, 26, 34, 54 BWG Antennas) - For all other BWG antennas, the following equations for modeled vacuum noise temperature apply:
S-Band: K (DSS 34, 54) X-Band: K (DSS 25, 54 with masers) X-Band: K (DSS 26, 34 with HEMTs) Ka-band: K (DSS 25)
The following configurations apply to the above equations:
S-band: S/X mode (S/X dichroic in place), non-diplexed, LNA-1 path (DSS 34, 54) X-band: X-only mode (S/X dichroic retracted), non-diplexed, LNA-1 path (DSS 25, 26, 34, 54) Ka-band: Ka-only (X/Ka dichroic retracted), non-diplexed, LNA-1 path (DSS 25)
The X-only mode for all antennas implies that there is a solid (flat) plate over the X-band horn. For an X-only antenna (DSS 26), this is the normal configuration. For an S/X antenna (DSS 24, 34, 54), this implies that the S/X dichroic plate is retracted. For an X/Ka antenna (DSS 25), and possibly future S/X/Ka antennas, X-only implies an optimum performance configuration for X-band in which the X/Ka dichroic is replaced by a solid plate.
The LNA and follow-on noise temperatures used in the above models are as follows:
S-Band: 6.0 K HEMT plus 0.3 K follow-on, referenced to LNA input X-Band: 3.43 K maser + 0.3 K follow-on, referenced to LNA input 9.7 K HEMT + 0.3 K follow-on, referenced to LNA input Ka-band: 28.0 K HEMT with cooled feed, including follow-on noise, referenced to feedhorn aperture
The modeled diplexer and additional waveguide noise contribution at S-band is 6.45 K, based on DSS 24 measurements. At X-band it is 10.6 K.
Table 9b shows modeled system noise temperature values as a function of elevation angle, for 25% CD average-clear weather as given in module TCI-40, Atmospherics, of this handbook, for all frequencies and configurations of all other BWG antennas.
Table 9b. BWG Modeled Operating Noise Temperatures with 25% Average Clear Weather
DSS 25 (Goldstone)
Band-MHz Mode Diplexed LNA Elevation (deg.) 90 80 60 45 30 20 15 10
X - 8420 X-Only No maser 23.40 23.58 24.22 25.08 26.65 28.89 30.98 34.97 X-Only No HEMT 33.90 34.08 34.72 35.56 37.11 39.31 41.37 45.30 X-Only Yes maser 34.00 34.17 34.79 35.61 37.13 39.28 41.29 45.12 X-Only Yes HEMT 44.55 44.73 45.33 46.14 47.63 49.75 51.73 55.50 X/Ka No maser 23.78 23.96 24.60 25.46 27.03 29.27 31.36 35.35 X/Ka No HEMT 34.28 34.46 35.10 35.94 37.49 39.69 41.75 45.68 X/Ka Yes maser 34.38 34.55 35.17 35.99 37.51 39.66 41.67 45.50 X/Ka Yes HEMT 44.93 45.11 45.71 46.52 48.01 50.13 52.11 55.88 Ka - 32000 Ka-Only No HEMT 46.90 47.13 48.38 50.41 54.64 60.99 67.14 78.93 Ka-Only Yes HEMT 47.90 48.13 49.38 51.41 55.64 61.99 68.14 79.93 X/Ka No HEMT 50.61 50.84 52.09 54.11 58.33 64.66 70.79 82.55 X/Ka Yes HEMT 51.61 51.84 53.09 55.11 59.33 65.66 71.79 83.55DSS 26 (Goldstone)
X - 8420 X-Only No HEMT-1 29.67 29.85 30.49 31.35 32.92 35.16 37.25 41.24 X-Only No HEMT-2 33.90 34.08 34.72 35.56 37.11 39.31 41.37 45.30 X-Only Yes HEMT-1 40.27 40.44 41.06 41.88 43.40 45.55 47.56 51.39 X-Only Yes HEMT-2 44.55 44.73 45.33 46.14 47.63 49.75 51.73 55.50DSS 34 (Canberra)
S - 2295 S/X No HEMT 29.45 29.58 30.10 30.84 32.24 34.45 36.44 40.16 S/X Yes HEMT 35.90 36.03 36.55 37.29 38.69 40.90 42.89 46.61 X - 8420 X-Only No HEMT 30.03 30.22 30.91 31.86 33.65 36.23 38.66 43.34 X-Only Yes HEMT 40.63 40.81 41.48 42.39 44.13 46.62 48.97 53.49 S/X No HEMT 33.26 33.45 34.14 35.08 36.88 39.45 41.88 46.56 S/X Yes HEMT 43.73 43.92 44.58 45.49 47.23 49.71 52.06 56.58DSS 54 (Madrid)
S - 2295 S/X No HEMT 29.45 29.58 30.10 30.84 32.24 34.45 36.44 40.16 S/X Yes HEMT 35.90 36.03 36.55 37.29 38.69 40.90 42.89 46.61 X - 8420 X-Only No maser 23.76 23.95 24.64 25.59 27.38 29.96 32.39 37.07 X-Only Yes maser 34.36 34.54 35.21 36.12 37.86 40.35 42.70 47.22 S/X No maser 26.99 27.18 27.87 28.81 30.61 33.18 35.61 40.29 S/X Yes maser 37.46 37.65 38.31 39.22 40.96 43.44 45.79 50.31
Figure 15 illustrates the estimated DSS 25 (Goldstone) noise temperature performance for Ka-band in a non-diplexed, Ka-band only configuration. Use of an X/Ka dichroic over the X-band horn (rather than a flat plate) will result in 0.38 K noise temperature increase as shown for DSS 25 in Table 9b.
Figure 15. DSS 25 (Goldstone) Modeled Noise Temperature; Ka-only Mode, Non-diplexed
2.6.7 Noise Temperature (HSB Antennas) - Figure 16 shows system noise temperature for the DSS 27 (Goldstone) S-band HSB antenna, based on measurements. This antenna operates in a diplexed mode only and employs a 45 K room temperature HEMT as its LNA. The vacuum noise temperature curve is shown, in addition to curves for five different Goldstone atmosphere conditions.
Figure 16. DSS 27 (Goldstone) Measured Noise Temperature; S-only Mode, Diplexed
For the DSS 27 S-band vacuum curve, the noise temperature is given as:
K
Figure 17 shows system noise temperature for the DSS 28 (Goldstone) X-band HSB antenna, based on a model. The vacuum curve is shown, in addition to curves for five different Goldstone atmosphere conditions.
Figure 17. DSS 28 (Goldstone) Modeled Noise Temperature; X-only Mode, Non-diplexed
For the DSS 28 X-band vacuum curve, the noise temperature is given as:
K
The LNA used in this noise temperature model is a 4.5 K Block-I maser.
Table 10 shows S-band and X-band noise temperatures as a function of elevation angle for 25% CD average clear weather as given in module TCI-40, Atmospherics, of this handbook for all frequencies and configurations of the DSS 27 and DSS 28 HSB antennas.
Table 10. HSB Operating Noise Temperatures with 25% Average Clear Weather
DSS 27 (Goldstone) Measured data
Band-MHz Mode Diplexed LNA Elevation (deg.) 90 80 60 45 30 20 15 10
S - 2295 S-Only Yes HEMT 102.92 103.04 103.78 105.28 108.92 114.20 118.71 125.92DSS 28 (Goldstone) Modeled data
X - 8420 X-Only No maser 26.18 26.22 26.60 27.44 29.74 33.72 37.62 44.59 X-Only Yes maser 36.78 36.82 37.20 38.04 40.30 44.32 48.22 55.19
2.6.8 Atmosphere Adjustment to Vacuum Noise Temperature - To account for atmospheric effects on total operating system noise temperature (T-op) for all antennas, atmosphere contributions at the elevation angle (el) of interest should be added to the vacuum expressions given above.
K where Tz = zenith atmosphere noise contribution as given in 810-5, TCI-40, for the appropriate antenna location, frequency, and weather cumulative distribution (CD). (dimensionless) = zenith atmospheric attenuation, dB, as given in 810-5, TCI-40, for the same antenna location, frequency, and weather cumulative distribution (CD).
Thus, the operating system noise temperature is given by:
K
2.6.9 Pointing Losses - Table 11 gives half-power beamwidth (full width) and pointing loss to be expected for BWG and HSB antenna pointing errors at S-, X-, and Ka-bands, for both uplink and downlink.
Table 11. 34-m BWG and HSB Loss due to Pointing Errors
Band S-Up S-Down X-Up X-Down Ka-Down Ka-Up Freq.(MHz) 2115 2295 7145 8420 32000 34000 HPBW (Deg.)* 0.250 0.231 0.074 0.063 0.017 0.016
Pointing Pointing Loss (dB) Error (Deg)
0.000 0.00 0.00 0.00 0.00 0.00 0.00 0.001 0.00 0.00 0.00 0.00 -0.04 -0.05 0.002 0.00 0.00 -0.01 -0.01 -0.18 -0.20 0.003 0.00 0.00 -0.02 -0.03 -0.40 -0.45 0.004 0.00 0.00 -0.04 -0.05 -0.70 -0.79 0.005 0.00 -0.01 -0.05 -0.08 -1.10 -1.24 0.006 -0.01 -0.01 -0.08 -0.11 -1.58 -1.79 0.007 -0.01 -0.01 -0.11 -0.15 -2.16 -2.43 0.008 -0.01 -0.01 -0.14 -0.19 -2.82 -3.18 0.009 -0.02 -0.02 -0.18 -0.25 -3.56 -4.02 0.010 -0.02 -0.02 -0.22 -0.30 -4.40 -4.97 0.012 -0.03 -0.03 -0.32 -0.44 -6.34 -7.15 0.014 -0.04 -0.04 -0.43 -0.60 -8.62 -9.74 0.016 -0.05 -0.06 -0.56 -0.78 -11.26 -12.72 0.018 -0.06 -0.07 -0.71 -0.99 -14.26 -16.09 0.020 -0.08 -0.09 -0.88 -1.22 -17.60 -19.87
* Half-power Beamwidth (HPBW = full width at half-power)
Table 12 provides the expected blind-pointing performance in various wind conditions. Pointing errors are given in terms of Rayleigh distribution, assuming equal pointing performance in the elevation (EL) and cross-elevation (X-EL) directions (equal Gaussian standard deviations). The mean pointing error for the Rayleigh distribution equals 1.25 times the standard deviation of the EL and X-EL pointing error distributions.
Table 12. Accuracy and Pointing Loss in Various Wind Conditions
Wind Speed Mean Pointing Range 0-3 Loss at Mean Pointing Error (dB) (m/s) (mph) Error (mdeg) sigma (mdeg) S-Band X-band Ka-band
<4.5 <10 1.67 0-4 0.001 0.009 0.123 <8.9 <20 3.33 0-8 0.003 0.034 0.489 <13.4 <30 5.00 0-12 0.006 0.076 1.101
An optional conical scanning technique for maintaining the antenna on point (CONSCAN) is available at S-band and X-band. A discussion of this technique is contained in module TRK-10, Angle Tracking, of this handbook. CONSCAN is not available at Ka-band because of the difficulty of moving the antenna structure at extremely small scan radii and the effect of atmospherics on the CONSCAN algorithm. Expected gain reduction due to CONSCAN are:
S-band: 0.01 dB when using X-band CONSCAN reference set for 0.1 dB loss at X-band X-band: 0.1 dB when using X-band CONSCAN reference2.6.10 Wind Loading Loss - In addition to pointing errors, wind causes a structural deformation of the antenna surface. This results in a reduced gain as shown in Table 13 for X and Ka-bands. The gain reduction at S-band is negligible for wind speeds up to 20 m/s (45 mph). Cumulative probability distributions of wind velocity at Goldstone are given in module TCI-40, Atmospherics, of this handbook.
Table 13. Loss due to Wind Loading
Wind Speed Wind Loading Loss (dB)* (m/s) (mph) X-band Ka-band
4.5 10 0.2 TBD 13.4 30 0.3 TBD 20.1 45 0.4 TBD
NOTE: * Worst case, with most adverse wind-antenna orientation.