Ku Band Internet Question

[gmockett]

I am helping a team of engineers with a new low cost phased array Ku band antenna for satellite television and internet (in-motion mass transit). We are presently trying to set the ranges for the chip specification which requires a firm definition of the RF frontend requirements. We would like some help confirming/setting these same. If those of you knowlegable in the space would review and assist that would be greatly appreciated.

We are looking at:

RX
frequency range: 10.7 to 12.75 Ghz (FSS and DBS)
bandwidth: >500 Mhz (1Gbps)
polarity: universal
IF out: 950 to 1950 Mhz
gain: 15 dB (per branch max amplitude)
noise figure: 3 dB (1dB with off chip LNA)

TX
frequency range: 13.75 to 14.5 Ghz
bandwidth: >500 Mhz
polarity: universal
IF in: 1800 to 2550 Mhz
RF power out: 20 mW (per branch-- 200 element array at 4 Watts)
gain: 15 dB (per branch max amplitude)

We need to clarify a couple of points:
1) While the chip itself may be polarity neutral, the front end design may dictate certain chip requirements--can we get away with a first generation antenna product that considers just R/L circular polarity and ignores V/H linear?
2) Can one get a decent television package with just the R/L polarity--even if it constrains band to the 12.2 to 12.75 Ghz?
3) Are there sufficient internet services in the above up/downlink frequency bands proposed that a) do not overlap (meaning that the up and down links are in distinct frequency bands) <b>and</b> b) use R/L circular polarity. (We know that there are linear polarity internet services with disctinct up/down link bands, but are not sure about circular.)
3) Conversely, is there sufficient television programming available in V/H linear polarity signals to warrant tossing out the R/L circular?

Thank you so much for any help you can provide.

--Greg

 

[grohgreg]

First, I'm not a ROTV engineer - so I might need some member support on that side of the discussion. I generally lean a bit more in the direction of 2-way satellite telecommunications. And are you leaving Ka-band out of the equation entirely? I would think that wavelength would lend itself more to your phased array approach.

Anyway, here's my opener:
1. This question must be qualified with a few more particulars. For example; what type of service - or which specific providers - will this system target? This is important, because there are architectural differences between/among pay TV, FTA, Canadian, US, Mexican, standard def, high def, circular, linear, et cetera. Local oscillator frequencies can vary between/among services and providers as well.
2. "Decent" is sorta relative I'd say. But a reasonable package maybe; like within one type of service, or from a specific provider. Otherwise - see above
3. again, see #1.

Some two-way Ku-band internet frequencies by the way are minorly segregated from the ROTV bands. You're looking at uplinks in the 14.0-14.5 GHz band and downlinks between ~11.5 and 12.2 GHz, polarization typically linear.

//greg//

 

[gmockett]

Thanks for responding.

Ku is pushing the boundaries of what is possible on an RF CMOS platform--we'll get to Ka band down the road. Immediately, though, up/down conversion might make the Ku chip work for Ka, though not cheaply enough to supplant reflector based solution today.

To the balance of your reply. You are hitting at the substance of my question. Sort of restating it. We are not familiar with all the services out there for sat tv/internet.

Taking a different tac . . . what system specifications (frequency, bandwidth, polarity, etc.) would encompass or facilitate the broadest number of services? and what specification ranges begin to severly limit these options? So, considering frequency, does the 10.7 to 12.75 cover just about every major package in CONUS/CONCAN for television and or downlink? --NOTE we are pretty confident in the specified frequency band, both in terms of inclusive boundaries as well as in ability to facilitate on chip.

Where we are really short on system info, is polarization. And polarity is an issue because we can add chip complexity to address polarization in the beamforming, or we can look at pushing this to the front end ahead of our chip (or to the back end by doubling elements and paths--which may actually still be feasible). So, from a syste perspective which services do we lose in television and internet if we elect to forgo certain beamforming complexity on the chip and push it out to the front end with a Right/Left circular polarity only compatibility? Are there any sat internet services in the afore stated down/uplink frequencies and R/L circular polarity?

I hope this clarifies. I look forward to your response.

--Greg

 

[grohgreg]

I guess what we (I) need from your engineers is a some sort of a mission statement. You're asking for pre-design input on how to do something, but I don't yet actually know what that something is. So first - will the users of this product pay a subscription for further services? Or will it be designed around the concept of subsequently free services? Or will the product provide it's own proprietary services? You used the word "mobile". Does that mean the reception/transmission be made while stationary - or while in motion?

10.7 - 12.75 GHz is the band you'll be receiving in. That's the easy part. From there you have to consider multiple LOFs and a mixture of polarization schemes. So - as above - it would help if you could define the scope of this project. But from a frequency standpoint, the uplink may be a challenge. The FCC has a 2 degree rule, which may be difficult to achieve with a moving phased array.

There are no North American Ku-band satellite internet services that I know of currently using other than linear orthagonal polarization. Emerging Ka-band services are demonstrating a shift to circular. Although having said that, I've never actually looked up the Ka-polarization on Galaxy 28. I'm not even sure what its Ka-capability is used for.

//greg//

 

[gmockett]

Really, we want to create an antenna. While a reflector is the epitome of universal (depending on the aperature, surface, LNB . . .) a phased array needs to be more specific. So, your question is fair. We want to put our antenna on trains, buses, aircraft, cruise ships, etc. It is our hope to be universal enough to allow the buyer to purchase subscriptions of their choice. We also want to insure that they can simultaneously pull down a decent internet service--also likely from subscription services available in band. As to the return path, our array should not have a problem complying with the FCC regulation due to our beamforming/shaping abilities.

So, having done more homework, I can confirm your position on internet links and polarization. Are there sufficient television subscription options available in north america for a linear orthoganal only array?

 

[grohgreg]

That question unfortunately hits me right in a weak spot. I suspect the answer is no, with respect to American subscription-based programming that is. All is not lost though, as some Mexican, Canadian, and FTA broadcasts may be linear-orthogonal. But for specifics in those arenas, we'll have to hope the member ROTV specialists will join this discussion.

//greg//

 

[elcuraalvarez]

Dear Friends
I have a problem with a modem HN9000, I put in the modem some cordenadas that are bad and the modem blockade, that is to say doesn't allow me to enter with IP 192.168.0.1, please I need to know if another ip exists for when the modem is blocked to be able to enter in the one.

Write me to : elcuraalvarez@yahoo.es

 

[elcuraalvarez]

I Need Help With HN9000 Modem

Dear Friends
I have a problem with a modem HN9000, I put in the modem some cordenadas that are bad and the modem blockade, that is to say doesn't allow me to enter with IP 192.168.0.1, please I need to know if another ip exists for when the modem is blocked to be able to enter in the one.

Write me to : elcuraalvarez@yahoo.es