Increasing Satellite Signal Quality

[cyberham]

If you have nothing to do, take a look at this video: Click here

The video shows an individual increasing the length of the small antennas inside an LNB. His purpose for this modification is to improve the LNB's ability to receive higher quality satellite signals. I'm not sure I believe this video.

Lengthening the antennas possibly will increase the signal level...but will it increase the signal-to-noise ratio which is what counts? After all, noise will also increase when using a longer antenna. He increases antenna length from maybe a little less than 1 cm to about 1.5 cm. Is this small change going to have any real effect? If it was this simple, then why wouldn't manufacturers simply install longer antennas (easy at the manufacturing stage) to improve performance?

Do you believe this video?

"If life was like that, then you wouldn't need Visa."

 

[primestar31]

If you have nothing to do, take a look at this video: Click here

The video shows an individual increasing the length of the small antennas inside an LNB. His purpose for this modification is to improve the LNB's ability to receive higher quality satellite signals. I'm not sure I believe this video.

Lengthening the antennas possibly will increase the signal level...but will it increase the signal-to-noise ratio which is what counts? After all, noise will also increase when using a longer antenna. He increases antenna length from maybe a little less than 1 cm to about 1.5 cm. Is this small change going to have any real effect? If it was this simple, then why wouldn't manufacturers simply install longer antennas (easy at the manufacturing stage) to improve performance?

Do you believe this video?

"If life was like that, then you wouldn't need Visa."

IF that worked, the companies that produce them would do it from the start.

Let's "ask the expert". Brian? Titanium

 

[NYDutch]

If you have nothing to do, take a look at this video: Click here

The video shows an individual increasing the length of the small antennas inside an LNB. His purpose for this modification is to improve the LNB's ability to receive higher quality satellite signals. I'm not sure I believe this video.

Lengthening the antennas possibly will increase the signal level...but will it increase the signal-to-noise ratio which is what counts? After all, noise will also increase when using a longer antenna. He increases antenna length from maybe a little less than 1 cm to about 1.5 cm. Is this small change going to have any real effect? If it was this simple, then why wouldn't manufacturers simply install longer antennas (easy at the manufacturing stage) to improve performance?

Do you believe this video?

"If life was like that, then you wouldn't need Visa."

The antenna length is tuned to a specific frequency range. Altering the length might dial a specific frequency in better if he knows what he's doing or at least gets lucky. Lengthening the antenna in hopes of grabbing more signal doesn't work unless the length is a multiple of the base frequency which wouldn't fit in the LNB housing. A larger reflector is needed to capture more signal assuming everything is dialed in correctly.

 

[arlo]

Lets see if I can do this. Just measured the probe lengths in two c band lnbf's. One a Titanium C2-W. Both were equal length measured as close as humanly possible w/o tearing them open.
Probe length: 18.313mm.
Frequency to wavelength calculator gives 4 GHz= 74.98mm.
Half of that. 37.49mm. Half wavelength.
Half it again. 18.745mm. Darned close. Epoxy gook got in the way.
So the probes are 1/4 wavelength. You could do the math and figure out what length would suit your desires.
A spectrum analyzer and signal source would be needed. You'd have to figure out how to defeat AGC using a receiver.
I did not look at the video yet. I just like "stuff".

 

[cyberham]

...Just measured the probe lengths in two c band lnbf's...

I went through some mental gymnastics similar to you. My favourite formula is 468/f (MHz) = 1/2 wavelength (feet). You can go from there at estimating how long an antenna should be for resonance.

I know a 5/8 wavelength vertical has a little more gain than a 1/4 wavelength vertical. But in this case, in the end, I doubt you would really end up with significant higher SNR. Likely it's not worth the trouble of messing around.

 

[arlo]

I went through some mental gymnastics similar to you. My favourite formula is 468/f (MHz) = 1/2 wavelength (feet). You can go from there at estimating how long an antenna should be for resonance.

I know a 5/8 wavelength vertical has a little more gain than a 1/4 wavelength vertical. But in this case, in the end, I doubt you would really end up with significant higher SNR. Likely it's not worth the trouble of messing around.

I know. I'm nowhere good at microwaves. VLF-UHF is more friendly. The "rules" are more forgiving. Microwave RF has stuff like modes and things I "get" but have a hard time grasping. Like TWT's, throwing in a tuning, or set of, tuning screws like high end 5G filters have.
A lot of time is spent I believe designing waveguides (feeds) and the lnbf circuitry.

It makes sense if the quarter wave probe(s) in what I see are tuned to 4 GHz. Shortening them will put the center frequency higher and lengthening them lowers the freq. But then you screw up the impedance match. And to do it right you really need to chase that part of the circuit. But sure. Mess around and have fun. All you can do is bork the once good lna, lnb, lnbf.
Microwaves are freaky. Notice when you crank the c band lnbf scalar screws into the feed and signal if affected because you distort the tube? On the cheaper, thin waveguide feed tubes that is. I got to wearing gloves when peaking the feed because bare hand(s) even detune things slightly.