Antenna, Reflector and Radome

Antenna

• Initial single-wavelength (W band) system will use a 15” diameter lens antenna

• A dual-wavelength feed and lens antenna is planned for the Phase C system

• Expected performance:

Beamwidth 0.6 degrees

Gain 48 dBi

Sidelobes -24 dB

Cross-pol. isol. -30 dB

f/D ~ 1.0

HIAPER Pitch Envelope

Reflector Plate

• Reflector plate rotates independently, nose cone/radome stationary

• Design to compensate for aircraft pitch envelope: 1° < pitch < 5°• Locate plate pivot point at near-field beamwaist a distance, f (15”)

from back of lens• At beamwaist: beam is 10” diameter @ 1/e2 (13.5%) power loss• Plate flatness: 0.005” rms to have negligeable effect on far-field

beam pattern• Elliptical design: 15.5” x 22.4” @ 0.8% power loss

Pod Beam Projections: Top and Side Views

Radome

• Sandwich design ensures:– structural integrity (FEA req’d) as well as high transmissivity (one way loss ~ 0.5 dB)– functionality at both W-band (94 GHz) and Ka-band (35 GHz)

• Compensate for radome induced phase errors distorting far-field beam pattern by applying low-loss SAN (styreneacrylonitrile) foam to reflector plate

• Use ray tracing to determine above compensation

Expected Radome Performance

• 94 GHz

Radome Phase vs. Incidence Angle(94.0 GHz)

-180-150-120-90-60-30

0306090

120150180

0 10 20 30 40 50 60 70 80 90

Incidence Angle (Deg)

Phas

e (D

eg)

Perp

Par

Radome Trans. vs. Incidence Angle(94.0 GHz)

00.10.20.30.40.50.60.70.80.9

1

0 10 20 30 40 50 60 70 80 90

Incidence Angle (Deg)

Tra

ns. Perp

Par

Expected Radome Performance

• 35 GHz

Radome Trans. vs. Incidence Angle(35.0 GHz)

00.10.20.30.40.50.60.70.80.9

1

0 10 20 30 40 50 60 70 80 90

Incidence Angle (Deg)

Tra

ns. Perp

Par

Radome Phase vs. Incidence Angle(35.0 GHz)

-180-150-120-90-60-30

0306090

120150180

0 10 20 30 40 50 60 70 80 90

Incidence Angle (Deg)

Phas

e (D

eg)

Perp

Par