Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Offset feed rectangular waveguide

Status
Not open for further replies.
L

lkminz

Member level 4
Joined
Jun 14, 2008
Messages
76
Helped
11
Reputation
22
Reaction score
10
Trophy points
1,288
Activity points
1,990
I am confuse with the design of this commercial product (product no - AN-3456-10), this is a Ku-band LNB .
it has rectangular waveguide for connecting antenna and that waveguide is connected to active component. transition from rectangular waveguide to microstrip line is through a probe which is not center feed.
the center feed is most common design I found so I was confuse why this design has feed position not at center.

The data sheet for A-3456-10 is not available, even the company selling it has not able to provide data sheet for this product.
I waveguide pic and active circuit pic is attached.

Kindly give your suggestions.

Thanks
 

Attachments

  • 20180716_104024.jpg
    20180716_104024.jpg
    426.5 KB · Views: 63
  • 20180716_104116.jpg
    20180716_104116.jpg
    517.5 KB · Views: 64

Thanks vfone
as per maximum coupling is concern I feel the probe should be at center. bcoz for TE01 mode the fields are maximum at center region.
that λ/4 criteria also in a way suggest to keep the probe at center from side walls.
Thats why I am confuse why this commercial product probe is not at center. ... searching little bit I found many such commercial products have off-center probe.
I really wonder why ?
 

I found that the offset of the probe is done when the LNB is used only for horizontal polarization, or for horizontal mounting on the antenna and use a polarization changer in front of it.

Also I found that some microstrip probes inside of the LNB are not in perfect vertical position, as in the example below:
https://imgur.com/0reBZGP

Some of them have an offset of few degrees (3.5° to 7°), which is used to reduce cross-polarization interferes when receiving signals from some satellites:
https://imgur.com/mccYZv5
https://imgur.com/MHXiiTP
 
  • Like
Reactions: lkminz

    L

    lkminz

    Points: 2
    Helpful Answer Positive Rating
vfone said:
I found that the offset of the probe is done when the LNB is used only for horizontal polarization, or for horizontal mounting on the antenna and use a polarization changer in front of it.
Click to expand...

this fact sound very interesting. can you give any reference to learn more about it.
Thanks
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top