......I break out tools, a software pyramidal horn calculator, take measurements and modify technology to suit my needs.
I laid my hands on an 8500x50 S7 for a very reasonable price. After riding with it for a couple weeks and researching the bloody hell out of it, I decided to make a slight modification. From what I have read the S7 has good all around performance. Specifically the balance of off axis & straight line detection as compared to the M4. So I decided to make a horn extension that altered the directivity a bit to better suit my needs. I do a lot of highway driving so a little extra range would be nice. And I was willing to sacrifice a bit of off axis sensitivity.
So I started playing around with some calculations 'till I got a theoretical balance I would be happy with. With a stock aperture of 29mm x 13mm, 34.7ghz had a sensitivity of ~38.5dB and an E plane front with +/- 2.3db over it's ~28 degree front. Now with a 60mm x 26mm aperture, 34.7ghz has a sensitivity of ~41.4dB and an E plane front with only +/- 1db over it's 25 degree front. And the roll off at the edges of the E plane front is a little more steep. Basically squeezed in the sides and pushed out the front. And the H plane narrowed a bit as well, but is within the range I was after. Which works for me since I could use a little more range.
After it was all done and assembled, I went for a drive around some known fixed K band location in a few parking lots to test the new range and off axis performance. Sure enough it worked like I wanted (I had taken some rough baseline distances before starting this little project with the same K band locations). I won't go into the explicit details because it would be kinda boring. I also wont go into the details of making the horn extension. It's just basic Arts & Crafts that we all learned in gradeschool......except I avoided eating any paste this time.
I realize this has been gone over / done before with some Whistler & Escort products. So I'm not trying to say I reinvented the wheel. Just thought I share my "Geek-out on the weekend project".
And now for some pics. Just for the heck of it.
Sorry I couldn't get a better pic down the horn without all the reflections. Flash + Foil + close up picture = sucky pic.
This was after I hit the outside of the horn with a light dusting of Silver spray paint to match it to the 8500x50 body. Partly for aesthetic, partly to keep the horn cooler in the sun.
I'll put 1000 miles on it during my next couple work weeks and report back on whether it is a success or failure. But anything I learn something from is a success to me.