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Another Good Resource On Indoor vs. Outdoor Antennas

The technical side of broadcasting. Think IBOC is a sham? Talk about it here! How about HDTV? Post DX reports here as well.
CK-722
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Another Good Resource On Indoor vs. Outdoor Antennas

Post by CK-722 » Sun Jul 21, 2019 11:39 pm

Any way you cut it,, Outdoor>Attic>Indoor 6 Feet Above Ground Level. Preamps are noisy, and don't give you gain like noise free gain from antenna placement and gain.

https://www.groundedreason.com/watch-tv ... nna-guide/


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Rich
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Re: Another Good Resource On Indoor vs. Outdoor Antennas

Post by Rich » Mon Jul 22, 2019 4:56 am

CK-722 wrote:
Sun Jul 21, 2019 11:39 pm
... Preamps are noisy, and don't give you gain like noise free gain from antenna placement and gain
Another benefit can result from using a directional outdoor antenna. It can reduce interfering signals arriving from co- and adjacent-channel stations with compass bearings well away from the direction of maximum gain of its directional pattern.

However this can be either good or bad, depending on the location of the receive site with respect to the location(s) of the OTA stations one needs/wants to receive. Using a mechanical rotor can remove that issue, but requires more of an investment in antenna system hardware and operator attention.

As for the effect of receive antenna clear-path elevation above (level) ground on the field intensities that exist at those elevations, below is a graphic showing that an approximately linear relationship applies. That is, doubling the receive antenna height above ground ~doubles the r-f voltage existing across the output terminals of the receive antenna (other things equal).

Elevating the receive antenna sufficiently may provide more improvement than that, if it reduces the propagation losses resulting from obstructed paths such as possible from nearby buildings, hills, etc.

Image



CK-722
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Re: Another Good Resource On Indoor vs. Outdoor Antennas

Post by CK-722 » Mon Jul 22, 2019 8:07 am

Proper orientation of a directional TV receiving antenna will ensure optimal reliability. It's hard to navigate various menus to find any DTV signal indicator, and then it's some kind of "signal quality" meter, that can be misleading. You are best off finding the azimuth to the station or stations, and using a compass or satellite view of your RL to orient it rather than the old analog "watch and bracket the best picture" method. Event when you think you have it right, you may find that there is drop out and pixellation for greater or lesser percentages of the time.


Is THAT where they got the idea for the 486-SX?

Same (x, y, z), different (t)

Your bullet missed my trial balloon.

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Rich
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Re: Another Good Resource On Indoor vs. Outdoor Antennas

Post by Rich » Mon Jul 22, 2019 8:57 am

CK-722 wrote:
Mon Jul 22, 2019 8:07 am
Proper orientation of a directional TV receiving antenna will ensure optimal reliability...
True, and sometimes the most useful orientation is not in the direction one expects.

For example, when I lived at the north end of Lincoln Park along the Lake Michigan shoreline in Chicago (late 1960s) and aimed my little UHF yagi toward South Bend, IN I got no signals at all. But when I aimed it at the top of a large, high-rise apartment building across the street to the west from me, South Bend UHFs were easy to receive.
Last edited by Rich on Mon Jul 22, 2019 12:28 pm, edited 1 time in total.



CK-722
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Joined: Sun Dec 16, 2018 3:53 pm

Re: Another Good Resource On Indoor vs. Outdoor Antennas

Post by CK-722 » Mon Jul 22, 2019 9:20 am

That ~14 dB increase between 6 and 30 feet, combined with a decent antenna with 6 dBd gain gives you the 20 dB increase often quoted. Michael Salvati, Ph.D. did some measurements like this that he showed in his books and articles. He also addressed preamplifier gain noise figures. Apparently, some of the best UHF preamps had transistors that were sensitive to static and were always blowing out junctions. Those might be good for indoor preamps though. At the time, Winegard had the Top Of The Line preamps. Seems like one had a 2 dB noise figure on UHF. TOTL Channel Masters were in the 4 dB noise figure range. But you can still lose all the preamplifier gain from preamps easily due to poor antenna location.

Dr. Salvati also had a good explanation of antenna aperture, which explained why the discontinued large Parabolic dishes were best for UHF frequencies. Peter Moncure, founder of Radiosoft, built some 16 foot Home Depot (Farm Supply Store for Chicken Wire, sounds "corny", but it worked!) Home Made Dishes that worked at VHF frequencies down to Channel 2, despite theory that said it had to be 10 X wavelength to work. Still probably easier to build than a rhombic, except for the horrendous wind loading.


Is THAT where they got the idea for the 486-SX?

Same (x, y, z), different (t)

Your bullet missed my trial balloon.

RTN Price. Not guaranteed. As of 12:30, 157.71 Down 0.22.

Artificial Intelligence is a Child that needs a Parent to guide it through.

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