Ba Lun is the English transliteration that balances converter, the principle is to press aerial theory, occasionally extremely aerial belongs to balance antenna, and coaxial cable is belonged to lopsided transmit now, if join its directly, of coaxial cable cortical high frequency electric current has flowed (transmit a principle by coaxial cable, high frequency electric current should flow in cable interior, cortical it is screen layer, be those who do not have electric current) , come so, the radiate that can affect aerial (the radiate that can imagine the screen layer into cable also participated in electric wave) .
Accordingly, be about to join balance converter between aerial and cable, flow into cable screen layer external electric current is clutched make, had shed Cong Zhenzi that is to say the high frequency electric current with cable screen cortical layer is cut off. Want to achieve such purpose to have a lot of kinds of idea, one kind is law of high frequency open a way, in cable screen layer cortical the sleeve that 1/4 good qualities receive a 1/4 wavelengh (be equal to effect the open circuit line of 1/4 wavelengh) , because 1/4 wavelengh opens a course to count open a way to this frequency, reach the action that blocks high frequency electric current, this kind of method, working bandwidth is narrow, sleeve of the 1/4 wavelengh when frequency is low appears very long, suit high-power tall frequency to use. Another kind is quits law, equal way is opposite and the voltaic size that thinks method makes flow into is mutual quits, apply the balance converter that 3 lines circle the more annulus that use magnetism to belong to this kind, this kind of frequency band is broader, use but the restriction that saturation of magnetism annulus magnetism accepts when high-power, suit low frequency small-power to use. Another is planted is transformer law, through high frequency transformer implementation balances changeover, the principle outputs transformer like push-pull same, alternate two-way balance electric current into but to lopsided electric current. Transformer can use magnetic core or circle into hollowly, applicable high-power is used. Still one is plant is to control a standard, brace up child receive cable screen layer through one high frequency choke cortical, prevent high frequency electric current to flow to cable screen layer cortical, this way is simpler, circle cable 10 rounds or so namely, it is better to be circled on magnetism annulus, also have nothing to do with hollowly, it is frequency commonly low circle much circle, frequency higher primary school is circled a few rounds. But it a few kinds are narrated before restraining the effect to do not have is good that before restraining the effect to do not have, a few kinds are narrated, accordingly in front a few kinds multi-purpose at major application, this kind of amateur application is more.
What should remember is we just cut off the high frequency electric current with screen cortical layer, not be all and high frequency electric current that cuts off layer of flow direction screen (want such word to disconnect skin of Zhen Zihe cable have to) , high frequency electric current flows inside of screen layer. Figure can imagine cable into conduit, should be water flows in conduit originally, if do not add Ba Lun, water flows in conduit not simply, and those who one part still sheds pipe is cortical. Ba Lun's action prevents to run namely, risk, drop, leakage, force water to flow in conduit, sth which it would be awkward to disclose, used! Pour V antenna make, it is to ask erect is gotten as far as possible tall, the 2 places that are erect want to be widened as far as possible, 3 it is to be far from interference source erect as far as possible.
Aerial brace up child HF uses general power supply cord (common weighs colored thread) go, insulation skin or naked copper cash are affected not quite, line choosing is a bit thicker can improve mechanical intensity and radiation efficiency (the effect not very apparent, theoretic thing) , through clip brace up child length makes aerial and cable match (effect of this one pace is apparent, be worth to be done seriously) . VHF can use aluminous canal or copper pipe, the size of pipe inspects mechanical intensity and decide, it is a bit thicker of course advantageous.
