HF antennas for Surface wave and Over the Horizon Radar applications

In this project we propose to design an electrically small antenna system for High Frequency Surface Wave Radar (HFSWR).Design improvements include the use of meander line to reduce size while maintaining the desired resonance frequency, the use of multiple-arm folding to increase the radiation resistance and the use of reflectors to further improve the directivity and increase the antenna gain. Based on the design (Fig. 1a) and the prototyping (Fig. 1b) of the proposed antenna, it is shown that these design improvements provided broader band coverage in the HF bandwidth with acceptable VSWR and increased radiation resistance without the need for stub-matching networks. The physical dimensions of the initial design is significantly smaller (in the longest dimension) than traditional quarter-wave monopole antennas.

Tasks:

  • The antenna is being modeled using FEKO and IE3D. Fig. 1a depicts the FEKO model of the proposed design where it may be seen that a two-arm folded antenna is used to improve the resulting value of the radiation resistance, and the feed system is placed at the center of the ground plane instead of at the end of the meander line. In addition, some emphases will be placed on the development of multiple operating frequencies in the HF band.
  • Development of new prototypes with improved radiation efficiencies
  • Continue with laboratory and field testing and measurement including locations along the coastline
  • Utilize DSP to facilitate beam steering capability when an array arrangement is used.

Fig. 1a. Model of prototype antenna            .

 Fig. 1b. Prototype antenna at test site.

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