[kwlug-disc] Home made indoor TV Antenna

John Johnson jvj at golden.net
Wed Apr 16 11:43:11 EDT 2014


Thanks Joe, for reading and commenting.
I did mention: additional elements, such as directors and reflectors, ...

I would put your Fresnel lens and waveguide and "boost" technologies 
would come under additional elements.

Regards
JohnJ

On 2014-04-16 11:28, Joe Wennechuk wrote:
>
>    
>> Basically: more metal in the sky == more captured signal (YMMV)
>>
>>      
> You can also use fresnel lense, or some type of waveguide antenna to boost the signal. There is a lot of DIY about this. I have never built one for Television, but I did do a Pringles can waveguide for wifi, and it was amazing how good it actually worked.
>
> ________________________________
>    
>> Date: Wed, 16 Apr 2014 11:11:13 -0400
>> From: jvj at golden.net
>> To: kwlug-disc at kwlug.org
>> Subject: Re: [kwlug-disc] Home made indoor TV Antenna
>>
>> On 2014-04-16 09:55, Colin Mackay wrote:
>> I have one of these:
>> <http://cdn3.volusion.com/m5ytq.j6phj/v/vspfiles/photos/CM-3000A-2.jpg?1385029454>
>> [ edit ]
>> Did try an 8-bay like in the walmart link above, to no avail.
>>
>> While I do not have recent experience with RF, my experience with
>> antenna technology goes back, way back. Perhaps, a decade or 2 or 3 or
>> 4.
>> That said, IMHO, the basic principles remain.
>>
>> Please note that I am trying not to sound pedantic. Nor write an essay.
>>      
>    
>> And I apologize for any perceived pedantry and the length.
>>
>> RF is really a higher frequency of the Electro-Magnetic radiation.
>>
>> And RF itself covers a wide range of frequencies, for the purposes of
>> this discussion from MW (medim-wave used for AM radio) though to
>> microwave.
>>
>> Excluding the plumbing and stripline technologies of microwave,
>> reception of the lower frequencies, including VHF, UHF, UHF-HD, etc.
>> depend on the first principle, i.e. signal capture.
>>
>> By "signal capture" I mean the capture of the RF radiation in "the
>> ether", in the desired frequency band. This "signal" will include a
>> multitude of channels or sources, each with its own content modulation
>> methods. This "signal" will also include channels or sources from
>> frequency bands outside of the desired frequency band.
>>
>> Presumably one of the channels or sources is the desired source in the
>> desired frequency band. After "signal capture" a variery of
>> technologoies come in to play to suss out the desired channels or
>> source from the "captured signal". These technologies include filters,
>> amplifiers, tuners, etc. And are not the point of this discussion.
>>
>> Returning to "signal capture", the first principle mentioned above,
>> involves the principle of induction, i.e. the generation of an
>> electrical signal in a conductor by the RF energy "in the ether".
>> Tesla, Hertz, Lenz, Faraday, Maxwell and Fessenden (a Canadian in the
>> bunch) and others have studied, researched and documented this process.
>>      
>    
>> However, basically, the strength of the induced electrical signal in
>> the conductor depends on the properties of the conductor and the
>> strength of the RF radiation at the point of induction.
>>
>> We cannot do much about the strength of the RF radiation at the point
>> of induction.*
>>
>> That leaves the conductor, and the properties of the same. One of the
>> properties of the conductor is its "size" or "length" relative to the
>> frequency of the RF radiation. The "size" or "length" of the conductor
>> can be used to "tune" the conductor to specific frequency bands. This
>> can be in a 1:1 relation (full wave) , or in 1:n where n is even
>> multiples, or more common n:1 where the conductor is in even fractions
>> of the frequency, e.g. half-wave, quarter-wave, etc.
>>
>> Basically: more metal in the sky == more captured signal (YMMV)
>>
>> IMO Antenna packaging like flying saucer is like that of fishing lures
>> at Canadian Tire. The item must first attract the buyer and whether or
>> not the item actually works in the wild is secondary.
>>
>> * Some technologies can improve the strength of the RF radiation at the
>>      
>    
>> point of induction. These include placement and orientation of the
>> conductor, i.e. antenna. These also include additional elements, such
>> as directors and reflectors, as seen on Yagi VHF antennas and the
>> bow-tie on on the Walmart HI-DEF antenna.
>>
>> /essay
>>
>> Regards
>> John Johnson
>>
>>
>>
>>
>>
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