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Forum Index : Electronics : Antenna 433MHz - Does it look right?

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Timbergetter

Regular Member

Joined: 08/10/2018
Location: Australia
Posts: 55
Posted: 05:14am 28 Nov 2018
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I purchased an antenna from a site with uncertain credentials and it was listed as “433 MHZ 6DBi WiFi Routing High-gain Omnidirectional Antenna”. I don’t have any way of testing the actual frequency of this antenna so I am hoping that someone here might be able to give an opinion on what I have received.

The coax braid and the bottom of the helix are bonded to the metal tube which extends for 25 mm below what I assume is the feedpoint.
 
disco4now

Guru

Joined: 18/12/2014
Location: Australia
Posts: 897
Posted: 05:48am 28 Nov 2018
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I can't help with what it is, but here is a link to a loaded coil one for 433MHz that
is easy to make. It could be used to modify yours if it turns out to be not what it says.


Here is one I used

Regards
GerryEdited by disco4now 2018-11-29
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Boppa
Guru

Joined: 08/11/2016
Location: Australia
Posts: 814
Posted: 09:21am 28 Nov 2018
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I know its a slightly different frequency, but my 6db uhf cb antenna on the ute (40mhz higher) is over 3/4 of a meter long, the 9db is a meter long....




  Quote  FEATURES

Ground Independent
Antenna Length 830mm (with 6db mast fitted)
Antenna Length 1230mm (with 9db mast fitted)



GME 6db antenna for 477mhz

Thats a GME, well known brand that makes arguably some of the best radios in the world, I dont see how a 10cm long one can possibly have the same gain....
 
brac321
Regular Member

Joined: 30/11/2016
Location: Slovenia
Posts: 54
Posted: 10:15am 28 Nov 2018
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Timbergetter, your antenna looks like a 2.5 GHz antenna. Dimensions on 433 MHz (70cm band) were quite larger...Edited by brac321 2018-11-29
OffGrid 24/7: 250w black mono solar panels 6.4kWp, 1x Midnite Classic 150, 1x MorningStar MPPT 60, battery bank 840 Ah @ 48v, modified LF-8K inverter, DC/DC, hot water harvesting, etc.
 
Timbergetter

Regular Member

Joined: 08/10/2018
Location: Australia
Posts: 55
Posted: 11:55am 28 Nov 2018
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Many thanks for your thoughts on this. I have read that the theoretical length of a ¼ wave whip would be around 170 mm and there are tricks that can be made to foreshorten this by using coils. Is it possible that the longer whips you are referencing are full or multiples of full wave examples?
 
Boppa
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Joined: 08/11/2016
Location: Australia
Posts: 814
Posted: 12:42pm 28 Nov 2018
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Yes, a 1/4 wave is a lot shorter, but then it wont have 6DBi gain....
 
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