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Tech Forum

2020 Issue-5

Assistance Against Cyber Attack

What materials make a good phased array antenna (i.e., efficient transmission and reception and the shape of the individual components)? What frequencies go through earth and seawater above 10 GHz also?

William Zimmerman
via email

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I’m curious about your impression of phased array antenna systems. What is it that you want to do?

Phased arrays are most commonly used in the AM broadcast band through the shortwave spectrum (500 kHz to 30 MHz). These arrays consist of a reference radiator and a number of phased radiators determined by the desired pattern. As frequency increase above 30 MHz different antennas types work better such as YAGI antennas or parabolic ‘dish’ antennas. Usually as the frequency goes higher, phased arrays are not practical.

As to your last question, water and water vapor ABSORBS radio frequency energy. The only frequencies that will penetrate water are in the VLF (very low frequency) band. WWVB (60 kHz) may be able to penetrate water, but this is about the highest frequency that possibly can.

You need to elaborate on your question. BTW, metal is always the best conductor for an antenna system. The efficiency of a system is determined by a number of factors. One primary factor is cable (coaxial) loss as the frequency increases (loss increases).

Douglas Hall, CPBE
Vilas, NC