| 摘要 |
A plurality of coaxially wound, untuned helical antennas have a pitch that is a function of displacement along the axis of the antennas. The untuned antennas may be excited by signals that have a selected phase shift therebetween. The excitation causes an additive combining of electromagnetic waves radiated by the untuned antennas. The helical antennas may be tuned to radiate the waves in respective bands of frequencies, thereby simultaneously providing filtering and radiation characteristics that make the tuned antennas suitable for frequency diplexing.
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