RESEARCH ON COMPACT AND EFFICIENT ANTENNAS.
Interim rept. no. 1, 1 Apr-30 Sep 66,
AIRBORNE INSTRUMENTS LAB DEER PARK N Y
Pagination or Media Count:
The research described is directed toward improving tactical communications antennas in the HF band. To facilitate the experimentation, modeling was done using scaled ground and scaled antennas. A carbon-loaded polyurethane elastomer was used to simulate dry ground. Although of finite size, the scaled ground sample used with various model antennas yielded elevation pattern data in substantial agreement with theory and permitted comparisons between different ground systems associated with the antennas. Water was also used as a simulating medium and permitted measurements to be made of surface waves and of the distribution of fields in different underground polarizations. A case is made for the adoption of standard grounds--dry, average, and wet--based on empirical quadratic relationship between dielectric constant and conductivity discovered by Albrecht. Tables and graphs of the reflection coefficients of dry and wet Albrecht grounds are given. Current work examines input impedance and ground-wave field attenuation characteristics using model antennas over model ground at microwave frequencies. The need for ground-wave test facilities in the HF band using a synthetic ground is pointed out. To this end research is required to relate the near-in ground wave to antenna efficiency. A measurable local figure of merit for a compact antenna is sought at an applicable range. Author
- Electrical and Electronic Equipment