RFE Ultrahorn Slant 45 Mod

RF Elements make an excellent lineup of horn antennas with a twistport waveguide antenna. Unfortunately they come out of the box in a H+V (Horizontal + Vertical) configuration.

Slant 45, or X polarity simply means that the H+V polarity signals have been rotated by 45 degrees to give a +45 and a -45 degree polarised signal.

Without getting into the benefits (or not) of slant 45 over H+V, there is a theoretical 3dB signal loss if you have a wireless link where each end is different. This means that when mixing antennas, it is important to have the same configuration at both ends of a link.

Here’s how to modify an RF Elements UH-TP-5-24 to slant 45.

Grab a Phillips screwdriver and remove the four screws holding the twist port.
Don’t drop screws into the horn, they are hard to retrieve!
Now use a torx bit to remove the four screws holding this red plate in place.
The red plate is attached to an inner ring of metal. Take note of the little arrow pointing straight up.
The keyway in the upper left is keyed to the red plate allowing only H+V orientation.
Grab some pliers and chop/break off this pesky little key.
Reattach the red plate. I always do mine 45 degrees anti clockwise, but it really doesn’t matter.
Attach the twistport.

The antenna is now in slant 45 configuration. Note that if you use twistport adapters, they will now attach tilted by 45 degrees unless you perform a similar modification to the twistport adapter.

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