| CPC G01S 13/56 (2013.01) [H01Q 9/42 (2013.01)] | 26 Claims |

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1. A half-wave back-folding directional microwave detection antenna for microwave detection, comprising:
a reference ground; and
a half-wave oscillator which has an electrical length greater than or equal to ½ wavelength and less than or equal to ¾ wavelength, wherein said half-wave oscillator is folded back to form a feed point at a position of said half-wave oscillator that a distance between a first end and a second end of said half-wave oscillator is greater than or equal to λ/128 and is lesser than or equal to λ/6, wherein said first end of said half-wave oscillator is defined as a far end of said half-wave oscillator and said second end of said half-wave oscillator close to said feed point thereof is defined as a feed end of said half-wave oscillator, wherein said feed point is offset from said far end of said half-wave oscillator and is close to said feed end of said half-wave oscillator, wherein said far end and said feed end of said half-wave oscillator are spaced apart from said reference ground with a distance greater than or equal to λ/128, and a distance between at least one of said far end and said feed end of said half-wave oscillator and said reference ground is lesser than or equal to λ/6, wherein a distance between said feed end of said half-wave oscillator and said reference ground is lesser than or equal to a distance between said far end of said half-wave oscillator and said reference ground, such that when said half-wave oscillator is fed for receiving an excitation signal at said feed point, said far end and said feed end of said half-wave oscillator form a phase difference and are coupled to each other, wherein λ is wavelength parameter corresponding to frequency of the excitation signal.
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