SLPS Calculation

[john peterson]

Hi - new to the forum and pretty new to electronics.

I have a calculation I'm trying to do that I could use a little assistance with, if someone has the time.

I am thinking about a small, (very low-powered ~10mW), radio project in which I would like to achieve a 90 degree phase shift. I was thinking of using a switched line phase shifter but then I thought about simply using a longer wire on the 2nd power feed.

The formula I found for determining the change in length of wire is: (don't know how to use the symbols so I'll type it out)

Change in phase angle = 2 X pi X change in length (of wire) X wavelength
Variables:
change in phase angle = 90 degrees,
pi = pi,
change in length = 'the unknown',
wavelength = 0.123017 meters.

I ended up with 116.4387432 and I think it is in meters, but I am not sure if that is correct - hence this forum post.

Could someone please help me with this calculation? As that seems like an awfully long length of wire to use to attain the 90 degree phase shift that I am hoping for.

I realize that there are other solutions - either digital or analog - but for now, I am only looking at this one solution for experimentation purposes.

Thank you.

 

[dr pepper]

I'd expect something in the order of 18mm.

 

[MikeMl]

299,792,458 metres per second/0.123017 meters = 2.437GHz or 2437MHz.

Put that in **broken link removed**, which lists velocity factors of several types of wire you might use (likely some kind of coax or stripline), so the velocity factor will be ~0.7

90 degrees occurs at 1/4 wavelength, so about 70% of the original 12.3cm/4.