DSN Antennas Gain and Aperture Efficiency
1. 70m DSN Antennas Gain
2. 70-m DSN Antennas Aperture Efficiency
3. DSS-24 34-m antenna
1. 70m DSN Antenna Gain
Following are the nominal values of the antenna gain vs elevation at L,
S, and X bands as
they are given in the DSN's interface document 810-5, Rev.D; Vol.I, (section
TCI-10, Rev.F).
The gain curves for K-band (22.24 GHz) have been derived from X-band curves
by using the Ruze equation. It was assumed that the rms half-pathlength
deviation of antenna surface consists of one constant component and one
variable. The last one is due to antenna structure variations when the elevation
angle is changed. Prior to the K-band gain curve calculation, the X-band
gain values have been corrected to remove some unique X-band (XRO) feedcone
losses (degradations due to dichroic plate, etc.).
The value of the zenit atmosphere attenuation Az at L, S and X-band also
are taken from the DSN interface document 810-5. The Az values at K-band
(22.24 GHz) are calculated by using formulas given in Report 564-4 of ITU
(International Telecommunication Union) for a standard atmosphere
(atmospheric water vapor content at the DSS43, 63 is standard, 7.5 g/m^3,
but at the DSS14 is 4.7 g/m^3) with weather conditions as defined in DSN
document 810-5.
The gain dependence from the elevation angle is given by formulas (valid
for elevation angle
> 10 deg.)
The following figures show the DSS14 gain variation vs. an elevation
angle at different wavebands and weather conditions:
2. 70-m DSN Antenna Aperture Efficiency
The value of an antenna gain is related to the antenna aperture efficiency
by the formula:
The following figures show the DSS14 aperture efficiency variations vs.
elevation angle at different wavebands and weather conditions.
3. DSS-24 34-m antenna
These curves are taken from figures 2-11 and 2-12 of JPL document 890-270.
They are based on holographic measurements.
The curve for a surface r.m.s. of 0.475 mm shows the performance prior to
panel setting optimization. (The operational requirement specification is
0.5 mm.)
From document 890-270, para. 2.2.3, the gain falls off 0.046 dB at 8.4 GHz
when the elevation changes by 33.8 deg from the peak gain at 40.8 deg, and
falls off 0.65 dB at 34 GHz when the elevation changes by 33.8 deg from
the peak gain at 51.4 deg. A full gain vs frequency and elevation model
still needs to be developed.
The curve below shows the antenna's potential for mm-wave operation. 