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          [Photo] Multi-element folded dipole antenna


          Half-wave dipole antennas and folded dipole antennas have low gain, wide lobe width, and the same reception capability in front and rear, so they are only suitable for places with strong signal and little interference.When the receiving point is far away from the TV station, the signal is weak or When the signal is strong but the interference is large, the reflected wave is more serious, you need to use a multi-element high-gain directional antenna.This is a multi-element antenna, also known as a Yagi antenna.Add a reflector behind the active oscillator and add a lead in front. The commutator constitutes a multi-element dipole antenna, leading to the dipole, the number of reflection dipoles and active dipoles is the number of antenna elements.
          The rear lobe of the multi-element antenna disappears, and the front sensitivity is greatly improved.The principle is as follows:
          1. The effect of the reflector on the signal from the P point in the front and the Q point in the back. The active vibrator in the right figure works in a resonant state, and its impedance is pure resistance. The length of the reflector is 5% -15% longer than that of the vibrator. It is inductive. Let the reflector be separated from the active vibrator by ?? / 4. The electromagnetic wave from the point P in front of the antenna first reaches the active vibrator and causes it to generate an induced potential e1 and an induced current I1. The electromagnetic wave then passes through ?? / 4. Only after passing through to reach the reflector, and causing it to generate an induced potential e2 and an induced current I2. Because the reflector and the active vibrator are separated by a distance of ?? / 4 in space, e2 lags behind e1 by 90 ?°, and I2 is reflected by the reflector. Inductively, it is 90 ?° behind e2, so I2 is 180 ?° behind e1, and the radiation field generated by the reflector current I2 reaches the magnetic field formed by the active vibrator H2 and it is 90 ?° behind I2, that is, H2 is 270 ?° behind e1. According to electromagnetic induction According to the law, the induced electric potential e1-2 generated by H2 in the active oscillator is 90 ?° behind H2, and the result is that e1-2 is 360 ?° behind e1, which means that the induced electric potential e1-2 generated by the reflector in the active oscillator and the original The induced potential e1 of the vibrator is in phase, the output voltage of the antenna is equal to the sum of e1 and e1-2, and it can be seen that the reflector allows the antenna to receive the main signal before The increase in sensitivity, according to a similar derivation can be seen: the role of a reflector of the offset signal outputted from the rear to the point Q.
          2. The role of the director The director is 5% -10% shorter than the active vibrator, and its impedance is capacitive. Assuming that the distance between the director and the active vibrator is also ?? / 4, the same method can be used to derive The following conclusions: The director acts as a booster of the antenna output signal to the signal from the front.
          In summary, the reflector plays the role of eliminating the rear lobe of the antenna pattern, and both the reflector and the director have the effect of enhancing the sensitivity in front of the antenna.
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          Multi-element folded dipole antenna

          Multi-element folded dipole antenna

          Posted at 2006-04-16 20:08 a€¢ 707 views
          Multi-element folded dipole antenna
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          Door Lock Motor Characteristics 1. No direction: don't need to distinguish the door direction, left and right sides, both inside and outside the door, can be universal. (convenient purchase locks and reduce inventory). 

          Door Lock Motor  Dc Gear Motor

          2. Power: the power consumption is only equivalent to one 5 of the electric control lock, electric lock, 3 A magnetic lock power to open the door, often consumes 0.27 A. And spiritual lock unlock instantaneous current is less than 0.5 A, reduced the entrance guard, talkback host power consumption.

          3. No collision: close the door without collision, reduces the choice of door closers requirements (not necessarily with 65 kg of door closers, door closers are free to choose to suit the door), to solve the building door because the door closers clash of the hydrodynamic force is too high, it is not easy to make the door more deformation, prolong the service life of the body. 

          4. The voice is light: close the door automatically locked, no noise, solves the noise due to electric control lock itself. 

          5. Life is long, life is up to 350000 times


          Operating temperature range:

          Mini Door Lock Motor should be used at a temperature of -10~60a??.

          The figures stated in the catalog specifications are based on use at  ordinary room temperature catalog specifications re based on use at ordinary room temperature  (approximately20~25a??.

          If a  Lock Motor  is used outside the prescribed temperature range,the grease on the gearhead area will become unable to function normally and the motor will become unable to start.Depending on the temperature conditions ,it may be possible to deal with them by changing the grease of the motor's parts.Please feel free to consult with us about this.


          Storage temperature range:

           lock motor  should be stored ta a temperature of -15~65a??.

          In case of storage outside this range,the grease on the gearhead area will become unable to function normally and the motor will become unable to start.


          Service life:

          The longevity of  Door Lock Motor is greatly affected by the load conditions , the mode of operation,the environment of use ,etc.Therefore,it is necessary to check the conditions under which the product will actually be used .The following conditions will have a negative effect on longevity.Please consult with us should any of them apply.



          a—?Use with a load that exceeds the rated torque

          a—?Frequent starting

          a—?Momentary reversals of turning direction

          a—?Impact loads

          a—?Long-term continuous operation

          a—?Forced turning using the output shaft

          a—?Use in which the permitted overhang load or the permitted thrust load is exceeded

          a—?A pulse drive ,e.g.,a short break,counter electromotive force,PWM control

          a—?Use of a voltage that is nonstandard as regards the rated voltage

          a—?Use outside the prescribed temperature or relative-humidity range,or in a special environment.

          a—?Please consult with us about these or any other conditions of use that may apply,so that we can be sure that you select the most appropriate model.


          when it come to volume production,we're a major player as well .each month,we rurn out  600000 units,all of which are compliant with the rohs directive.Have any questions or special needed, please contact us, we have the engineer group and best sales department to service to you

          Looking forward to your inquiry. Welcome to our factory.

          Lock motor


          Door Lock Motor

          Door Lock Motor,Mini Door Lock Motor,Door Lock Dc Motor,Door Lock Gear Motor

          Shenzhen Shunchang Motor Co., LTD. , https://www.scgearmotor.com

          亚洲 欧美 图片 自拍 视频
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