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simple 433mhz antennas?

Discussion in 'General Electronics Chat' started by NleahciM, Jun 17, 2005.

  1. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Re: reply

    He's already said that he worked it out incorrectly (full length instead of quarter). However, a full length whip would be no good for the receiver either!, although it won't damage the receiver (as it may the transmitter!), it still won't work properly - the severe mismatch will reduce the reception sensitivity just as on the transmitter it will reduce the transmitter output.
     
  2. NleahciM

    NleahciM New Member

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    Re: reply

    yeah - I hadn't realized that there was a second page to this thread, so I missed his correction :eek:

    So it'd be better to use two quarter wave antennas?
     
  3. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Re: reply

    Depends what you mean by that?.

    A dipole is the basic aerial element, and is the standard against which all other aerials are compared. A dipole basically consists of a quarter wave element connected to the inner core of the coax, and another quarter wave element connected to the screen of the coax. This effectively gives a half wavelength aerial, with the connection in it's centre.

    A quarter wave whip is essentially the same device, the 'ground' half of the dipole is reflected in the ground plane that the screen of the coax connects to - for a standalone aerial, you usually have a number of horizontal rods projecting sideways from the base of the aerial, on a car the car body acts as the ground plane. For a 433MHz transmitter or receiver the metal box you install it in acts as the ground plane - if you use a plastic box, it won't work as well! - often suggested PCB layouts include a ground plane in the copper track around the aerial connection.
     
  4. dave

    Dave New Member

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  5. zachtheterrible

    zachtheterrible Active Member

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    Hi NleahciM, I've got a couple 433MHZ tx's n rx's. I just used a 36cm piece of wire for my whip antenna and it worked wonderfully.

    Direct line of sight, I probably got around 500 ft or so, and the signal still showed up, I couldn't go any further to test it though (i live in tract homes :cry: )

    Going through a house, I got around 100ft.
     
  6. xavierp_00

    xavierp_00 New Member

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    antenna question too

    Hi, I´m building a really small low-power reciever and I would like to know wich antenna should I use to recieve at 433 Mhz, the smaller one.. It would be great for it to be internal.. I found many different searching arround but I'm nor sure... tahnks!
     
  7. Superbat

    Superbat New Member

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  8. JimB

    JimB Super Moderator Most Helpful Member

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    Did you have to resurrect a three (going on seven) year old thread to provide this snippet of information which is also wrong.

    JimB
     

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