always choosed the wrong antenna

scandiskwindows9x

Moderator of DTV Latino
#1
Hello to everyone:

i today purchased an rooftop antenna for an set up for my aunt i got an UHF 12 elements antenna 11.5DB gain this one Antena Exterior FA-12 UHF but i am amazed because i tested on my home indoor that antenna and picked up all the digital stations with at 73% of signal strength and signal quality 90-97% is even better than my antenna that have on my own set up my question is what factor can make an rooftop antenna better or worst in terms of pick up electromagnetic signals i have o9n my set up this antenna http://www.citltda.cl/antenas/prohd1100.pdf and i never got in outdoors 70% of signal strength even being with higher gain than this one that i have for the set up.

i am now wondering if always choosed the wrong type of antenna or need to watch by the antenna build

best regards
Francisco
 
#2
The Devil is in the Details

You have one ad stating 11.5 dB and another stating 15 dBi. You need much more information before you can make a decision for any given location. First of all, you need to know whether the 11.5 dB figure is dBd or dBi or some other metric. Second, one number can't possibly apply to every frequency. Are these numbers averages, or maximums or minimums? If they are averages, what KIND of average? Are they means? Modes? Medians? Over what range of frequencies?

Then, once you get that statistic pinned down, you need figures for beam width and SWR, and you need all this for every frequency you're trying to receive. Then you have to decide whether the manufacturer is a reliable source for any of that information.

For the major antennas made by American companies, we have independent experts doing simulations as well limited direct testing with professional equipment, so we have some means of comparison. But saying an antenna is 11.5 dB is like saying a pair of pants is 3 feet -- for what dimension?? Are they stretch pants? Are they shorts? What are we talking about?

Then we have the fact you are trying to compare antennas in an indoor situation. In general, if an antenna is better outside it's usually better inside, but there are no hard and fast rules. Indoor reception is a crap shoot, and luck will be a much bigger factor than any little 3.5 dB difference.

Rick
 
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scandiskwindows9x

Moderator of DTV Latino
#3
i know thaqt the antenna that got for my aunt do not have the specs and is a shame that but oddly outperform to the ones that got and are imported from brazil or china is strange say this but in my indoor test never got 70 percent signal strenght in fact in outdoors never have got a reliable 70 percent of strenght of signal always been a faint 50 percent i do not have explanation tend to think that i will forgot of purchase imported crap of antennas and prefer the national product, the antenna that got is made in Chile and i am amazed by the performance in indoor and my house have walls of brick and is not easy pick up a reliable signal in such conditions.

is some way of know what is the real gain by doing measurement or something like that? what is the difference between dBd and dBi?

also for antennas is not metric measurements for the gain is the decibel the measurement used
 
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Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#4
Francisco,

Glad to see you back here!

As you know, a digital signal reported on your television "meter' at 20 isn't any clearer than a signal shown at 90. The antenna that collects a signal at 90 MAY be more dependible in bad weather but that is all.

Jim
 

scandiskwindows9x

Moderator of DTV Latino
#5
i do not use anymore converter boxes just keep 2 from those just 1 is on service, had to renew all our televisions because got broken, the tv we have is LG-sony and the meter is nice get signal strenght and signal quality on those, the sony is just crap just show signal strenght or quality no idea just am disappointed of the sony tv nin fact always had problems of MPEG4 artifacts in a heavy rain situation just on edges looks teared or with noise like pixellation on edges and never now get more of 50 percent of signal strenght but signal quality is 100 percent or near 100
 
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