PERFORMANCE CHARACTERISTICS OF HIGH FREQUENCY ANTENNA SYSTEMS FOR MARITIME MOBILE BANDS
Applicability of generic types of hf antennas to shipboard use is discussed. Each type is sized considering the lower five hf maritime bands with pattern and impedance data being presented together with a discussion of efficiency for the tuned verticals. Types of antennas considered include: 1) Tuned base-fed vertical masts. 2) Tuned sleeve verticals with elevated feed systems in both electrically small and nonelectrically small versions. 3) Base-fed broadband "cage" verticals. 4) Top-fed broadband "cage" verticals (discones). 5) Tuned wire fans. 6) Horizontal directional log-periodic arrays. 7) Combinations of the above types. Use of sleeve verticals provides greater radiation pattern bandwidth than can be obtained with base fed verticals and especially those with significant top loading. A comparison of two sleeve designs having near-identical radiation patterns but much different efficiencies at low frequencies is made; one version being electrically small while the other is not. Cage verticals are the simplest types of broadband antennas available for this service. Specific data on cage dimensions and wire sizes is given. Merits of each type are presented together with data - some of which is computed using a modern ring-array analysis program and some of which is measured full scale. Twin fans, as have been used by the Navy for some years in the MF and lower HF bands, are discussed relative to their suitability as high angle skywave radiators in addition to groundwave. Recently developed high angle pattern data from NELC is presented for two typical ships. In several recent instances, use of specially designed horizontal and rotatable directional log periodic arrays have proven that reliable long range hf communications is possible onboard ships. Practical designs are likely limited to the 8 MHz low limit except when used in combination with dipoles or cage verticals. A survey of the several types of these antennas is presented and a relative size comparison is made.
- Presented at the April 24-26th 1972 New Orleans RTCM Assembly Meeting. Volume 1-Papers AA and A thru F-Marine Traffic Systems, Volume 2-Papers G thru L-Safe Ship Operations, Volume 3-Papers M thru Q-Maritime Satellite Systems, Volume 4-Papers R thru Z-Trends in Maritime Communications. SOLD ONLY AS A COMPLETE FOUR VOLUME SET $10.00 PER SET.
Radio Technical Commission for Marine ServicesP.O. Box 19087
Washington, DC USA 20036
- Cory, T S
- Publication Date: 1972-4-24
- TRT Terms: Antennas; Communication systems; Radio; Radio wave propagation
- Old TRIS Terms: Antenna systems
- Subject Areas: Marine Transportation; Operations and Traffic Management;
- Accession Number: 00033721
- Record Type: Publication
- Source Agency: Radio Technical Commission for Marine Services
- Files: TRIS
- Created Date: Sep 15 1972 12:00AM