The Tvfool report , Digital Current Plus Pending Applications Included Channel List and Radar Map shows that , Main Group of Tv stations , the Tv station you will like to receive are to the South.
( KBTX-DT , Real UHF Tv channel 50 , is to the , west north west , and is Strong Signal Strength. )
The Tv transmissions and reception to the South Strong Signal Strength.
Do Not use any type or kind of amplified antenna or any type or kind of antenna system amplifier.
Reasons , the signals are strong so no requirement for a amplifier.
And because of the close buildings around your office building , Tv signals will be bouncing all around , this is called Multi-Path , multi-path is not good for reception.
Using any type or kind of amplifier , will also amplify the multi-path
, making multi-path stronger is not good.
The correct action is to make multi-path weaker.
I recommend install/place a Non amplifier indoor type antenna , in/at the window that is in the , south type direction.
Use a Non amplified , Terk HDTVi Non amplified antenna , not the Terk HDTVa amplified antenna.
The Terk HDTVi antenna has the , long metal reception rods for the VHF channels 2 thru 13 and the multiple metal reception elements antenna for reception of the UHF channels 14 thru 51.
Aim the Terk HDTVi antenna at about 180 degree magnetic compass direction.
Here is how to aim indoor and outdoor antennas ,
www.kyes.com/antenna/pointing/pointing.html
If a Long coax running through office is required to connect the HDTVi antenna that is in/at the window to the Tv then , So Be It.
Here are some places to buy antennas and etc. .
www.solidsignal.com
www.amazon.com