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Radiation patterns were measured using a linear, polarized transmitting antenna and the coordinate system shown in Fig. 11. The antenna was mounted on a circular ground plane, one wavelength in diameter, for all tests. Polar plots were measured every five degrees, and the data were graphed on a contour diagram as shown in Fig. 12. Maximum measured gain for the antenna is 3 dB above isotropic, with the main lobe in the direction of ϕ = 270 deg, θ = 45 deg.

Conclusions

Initial development indicates that the field distribution is similar to the rectangular slot, and the radiation patterns indicate peak gain levels which are higher than a dipole. This would indicate good efficiency.

Techniques are being investigated to further improve bandwidth and other performance characteristics with the many design parameters available. Printed-circuit and strip-line applications are also being considered to further reduce the weight, and simplify fabrication and assembly problems. Other disc and slot shapes are presently being investigated to provide useful antenna types easily adaptable to airborne vehicle structures.

References

  1. John D. Kraus, Antennas, (McGraw-Hill, 1950).
  2. Avco In-house Development Report, RAD TR-64-35.
  3. G.A. Bakalyar, “High Altitude Breakdown Prediction.” NASA TM-33-280.