Why do I have reception only below freezing
 

http://www.tvfool.com/?option=com_wr...5b94141d8be2a8
This is my current setup
2-HDB91X
1-91XG
CM7777 preamp
I currently get channels 8(abc),18(abc),39(ion). I can receive channel 46(NBC) only when it's below freezing. The colder it gets the better I receive it. I understand less heat less signal distortion, but why only below freezing ?

For the same reason we can hear farther under water.
Tighter molecules, along w/ less heat distortion, as you mentioned.

You can verify this, by driving past businesses that have burglar alarms/ door openers and a radar detector. In warm weather, you need to be right on top of them to activate the detector and in colder weather, you can be considerably farther away.

Properly running cars, also run better in cold weather.

Makes sense. But dang I sure wish I could pull it in all the time.

Well, your system certainly is no slouch.
Have you played w/ different heights?

Sometimes, just moving the antenna around, or up/down a few inches, will find the sweet spot?

No I haven't messed with the height any. That's now on my to do list.

what?

Door Openers and Alarm System Motion Detectors run off of Inferred
They see a difference in heat from the previous measurement

I would check if you have water in your system.. either in the preamp or tubes or wires. Cable Companies send crews around all the time due to those problems which are weather related.

Different frequencies of radio/tv waves are effected more dramatically by small losses. If you lose 3db ... i can't remember right now which end of the spectrum but its something like you can lose 3db on high uhf and feel very little effect but on vhf or low uhf it can drop out your signal... again could be reversed i forget and its almost 2am...

but IR or PIR motion detectors cars .. all that other stuff... nah blah.. nothing to do with radio waves...

Thanks I'll give it a try

Many commercial door openers back in the day used X-band radar for motion sensing. Used to set off the radar detector from a 1/4 mile away from supermarkets and the like.

I haven't used a detector for almost 20 years, so I can't comment on what's currently in use, but I can confirm that radar frequencies were in use previously for this function.

Yes, it has been at least 25 years, since I've used one too.

I even remember using the old separate TX/RX ultrasonic motion sensors, that you could actually hear.