8 wood antenna makes FM3 unit

8 wood antenna makes FM3 unit:



Optional diameter is the material that make the copper of 6~8mm, aluminium or stainless steel canal, I chose the stainless steel control of the easiest draw materials to make namely, whole deputy antenna sparkles shine, very beautiful, never rust, receive the result pretty good. The friend that have fun at can try oh.


 

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The join of aerial and line of make a present of, it is the very serious problem when installing antenna. If join is incorrect, will immediate impact receives the result. Its join means, depend on the active in aerial brace up child the sort of appearance and line of make a present of. Have following case commonly usedly commonly.
One, the active of aerial brace up child close for half twists and turns brace up child (impedance 300 ω ) .
When line of join make a present of introduces line of 300 ω compressed make a present of, its join way is the simplest, be about to two lead of line of make a present of are received respectively in active the mouth between Zhen Zizhong is in can, if pursue,1 place is shown. If use 75 ω coaxial cable to make line of join make a present of, its join means needs to add up to half twists and turns brace up child 75 ω matchs commutation of 300 ω impedance and coaxial cable. The method is to carry the coaxial cable of 2 wavelengh of / extraction 1 to make u transformer, if pursue,2 are shown. First 1 / among the coaxial cable of 2 λ the two end of core line, receive the mouth that combines Zhen Zitian line in half twists and turns to be in, its are outer screen net is linked together; Advocate the either end that the core line of line of make a present of receives aerial mouth to be in, the screen net of transformer of form of u of join of its screen net.
2, the active of aerial brace up child it is half brace up child (impedance 75 ω )
When line of make a present of introduces line of 300 ω compressed make a present of, need to undertake impedance alternates, the line of compressed make a present of that the method is 4 wavelengh of the / that use 1 makes impedance transformer twice, if the graph is shown 3 times,receive a standard.
When line of make a present of uses 75 ω coaxial cable, need to have a balance only - lopsided changeover, can use 75 ω to make u form transformer with axes, if the graph is shown 4 times,receive a standard. Take the coaxial cable of 2 λ of / of a 1 , at aerial two termination the mouth is in and will outer had been linked together; Again in u form transformer 4 λ place cuts off 1 / , its advocate the core line of line of make a present of receives the line of coaxial line core that in 1 / 4 λ manages, its are outer screen line receives the line of coaxial line core that in 3 / 4 λ manages.
In addition, still can make with double aperture magnetic core. Its make a method see a picture 5 (a ) , (b ) be shown.
The outstanding advantage of transformer of impedance of double aperture magnetic core is bandwidth of bulk small frequency, defect is interference rejection ability and alternative difference.




 

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