[SATLUG] OT: Built my own DTV antenna

Jeremy Mann jeremymann at gmail.com
Sun Apr 26 10:22:48 CDT 2009


I finally got on the DTV bandwagon this weekend. I received my HD
receiver and hooked up my Radio Shack powered rabbit ears. I scanned
and got 3 channels. Not too bad I thought since even on just straight
rabbit ears I've never received a good signal. I began experiementing
with various antenna projects I found on the 'Net and settled on the
project using 8 wire coat hangers in a criss cross fashion. Now I get
10 channels and an occasional blip losing a channel.

This morning I discovered something interesting, when I get signal
degradation (as monitored by the Antenna meter in the HD receiver), my
11g wireless network has a momentary loss as well. I don't see how the
wireless network could have the same problem when its using a
completely different radio spectrum, 2.4Ghz for wireless and
600-700mhz for the DTV antenna.

I found this while researching the problem:

"DTV operates on various frequencies that have been previously
allocated to VHF and UHF broadcasts.  The highest channel allocated to
DTV is Channel 51, which has a center frequency of 693.25 MHz.  A WiFi
router, on the other hand, operates on a frequency range centering on
2.4 GHz, which is much higher.  They are not close enough to interfere
with each other, although in some circumstances overmodulation on the
DTV channel might spill over some extraneous harmonics into the 2.4
GHz range. As such, you might be more concerned about your DTV antenna
amplifier interfering with your WiFi network than the other way
around."

Can somebody explain in laymans terms "extraneous harmonics"? I'm just
curious because I'm NOT using an amplified antenna so I shouldn't be
affected by this problem.

-- 
Jeremy Mann
jeremy at biochem.uthscsa.edu

University of Texas Health Science Center
Bioinformatics Core Facility
http://www.bioinformatics.uthscsa.edu
Phone: (210) 567-2672


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