Electronics > RF, Microwave, Ham Radio

Interesting Kathrein 70cm train antenna design

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wkb:
I got my hands on an interesting Kathrein 70cm antenna designed for use on trains. Originally it was equipped with a funky proprietary Kathrein coax connector. This stainless steel connector was equipped with a spring-loaded silver-plated pin inside a silver-plated brass tube.
Very nice engineering, my guess is that this was done to ensure continuous contact in high vibration situations(?).

Given that I did not fancy spending like EUR 15 on a suitable plug, I rebuilt the antenna using an N connector. Versions with N connector are also produced by Kathrein btw.  It is built like a tank (well.. train I suppose): Nylon cap, diecast aluminium, stainless steel etc.

Would be interesting if someone could explain the design...  Or model it in something like EZNEC. Note that it requires a groundplane (read: train) to work properly.

Theboel:
Sorry what the enclosure material ? Is that stainless steel ?

wkb:

--- Quote from: Theboel on January 22, 2016, 11:26:27 am ---Sorry what the enclosure material ? Is that stainless steel ?

--- End quote ---

The black stuff is Nylon.

T3sl4co1l:
Yabbut it doesn't look black, it looks metallic, and shiny around the edge..?

If it is nylon after all, then it'll have little effect on the fields, and you'll have something like a patch antenna there.  Curious that they have a tuning "foot" on it.  I would expect the radiation pattern is typical of any 1/4 wave whip type antenna, or patch or whatever.  Bandwidth will be on the low side.

Tim

wkb:

--- Quote from: T3sl4co1l on January 22, 2016, 04:07:02 pm ---Yabbut it doesn't look black, it looks metallic, and shiny around the edge..?

If it is nylon after all, then it'll have little effect on the fields, and you'll have something like a patch antenna there.  Curious that they have a tuning "foot" on it.  I would expect the radiation pattern is typical of any 1/4 wave whip type antenna, or patch or whatever.  Bandwidth will be on the low side.

Tim

--- End quote ---

Ah, misunderstanding on my part I think: the shiny stuff that the N connector is mounted on is die-cast aluminium.

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