10/23/09

The Channel Master 2020

 

http://www.hdtvprimer.com/ANTENNAS/CM2020.jpg

http://www.hdtvprimer.com/ANTENNAS/CM2020VHFaz.gif

http://www.hdtvprimer.com/ANTENNAS/CM2020VHFel.gif

http://www.hdtvprimer.com/ANTENNAS/CM2020UHFaz.gif

http://www.hdtvprimer.com/ANTENNAS/CM2020UHFel.gif

 

61” wide, 22” high, 90.5” deep,

Antenna weight: 5 lb. 

 

Announced long ago, this antenna is finally available.  As a channels 7-69 antenna first delivered after the digital transition, this antenna was obsolete on day one.

 

Its VHF portion is a bit weak.  It is a good choice for close suburban locations with obstructions, where a strong UHF antenna is needed but the VHF part can be medium strength.

 

The UHF part is 60 inches long.  The poor performance on channels 14-30 is due to poor isolation between the VHF and UHF parts.  (The quarter-wave stub is meant to serve as isolation: it is a short circuit for UHF.  But it is perfect for only one frequency, roughly channel 45, and gets less effective further away.  The UHF picked up by the VHF antenna sometimes adds, sometimes subtracts with what the UHF antenna receives.  This gives the plot the roller coaster appearance on the ends of the band.)

 

 

 

 

 

 

 

 

This page is part of “An HDTV Primer”, which starts at    www.hdtvprimer.com