FCC Reinstates DISH Ka-Band License

[Steve Mehs]

The International Bureau at the Federal Communications Commission reversed an earlier decision to strip EchoStar of one of its Ka-Band authorizations, saying the company demonstrated that it's meeting milestones to build and launch the next-generation satellite system.

FCC documents acquired late Monday said EchoStar's petition for reconsideration of the initial FCC order - which took away the original Ka-Band license - had "additional evidence not previously presented" concerning EchoStar 9, the hybrid C-Band/Ka-Band bird being constructed for the company. While the commission typically doesn't grant petitions for reconsideration based on new evidence, the new facts concerning the first order required a reversal that's in the public interest, the agency said.

"The public interest in seeing EchoStar's Ka-Band services brought to the public outweighs any harm caused by EchoStar's failure to provide this information as part of its initial milestone compliance demonstration," the FCC order said.

Ka-Band, considered the next big thing in satellite systems, is expected to deliver satellite broadband and advanced video services.

From SkyReport (http://www.skyreport.com/skyreport/nov2002/111902.shtm#one) (Used with Permission)

[Mark Holtz]

(Raising hand) Uh, teacher, if DBS utilizes Ku-band technology, then what does Ka-band technology do? Is it a different part of the spectrum?

[James_F]

The Ku-band
The Ku-band is generally considered to extend from 12 to 18 GHz. However, satellite communication engineers use the term "Ku-band" to refer to an extended frequency range from 10.7 GHz to 18.4 GHz. This frequency range actually includes part of the X-band (8-12 GHz) and part of the K-band (18-27 GHz). Almost all Ku-band satellite systems employ at least part of the X-band frequency range (10.7-12 GHz), whereas relatively few utilise the K-band frequencies (18.0-18.4 GHz).

The Ka-band
The Ka-band extends from 27 GHz to 40 GHz. It includes the upper part of the SHF band and the lower part of the Extremely High Frequency (EHF) range, which extends from 30 to 300 GHz. Commercial Ka-band satellites systems typically employ the 27.5-30.0 GHz SHF frequency range for uplink transmissions (earth-to-space) and the 17.7-20.2 GHz range for downlink transmissions (space-to-earth). Once again, satellite communication engineers use the term "Ka-band" rather loosely, since most of the downlink frequency range actually falls within the K-band and even overlaps with the Ku-band.

What are the differences
There are two main consequences when moving from the Ku-band to the higher frequencies of the Ka-band. The first is that, for a fixed parabolic antenna ("dish") size, the beam becomes more concentrated at Ka-band, providing higher gain and a narrower beamwidth. This offers the potential for smaller earth terminals than is currently possible in the Ku-band. However, as a consequence of the narrower beamwidth, the susceptibility to antenna pointing errors increases and the antennas on-board the satellite become more complex. The second consequence is the effects of the weather become more severe at the higher frequencies. It is the task of the system designer to balance these advantages and disadvantages so that the potential of the Ka-band is fully exploited.

[Mike123abc]

Comparisoin of Ka vs Ku as far as DBS is concerned:

Ka/Ku
Separation required -- 9 degrees / 2 degrees
Frequency allocation -- 720 MHZ / 500MHZ
Transponders/slot -- 46 / 32
Spot Beam size -- 500+ / 120+ miles

Note that the smaller spot beam size is an advantage allowing a spot to hit just one city and not for example cover the whole NE as with Ku.

The main problems with Ka is that rainfade could be a real problem, requiring much more power from the satellite to overcome it, some estimates that it could require up to 10x the amount of power of Ku band. Dish was arguing that they needed to put up a satellite with a transponder on it to test it to see if they could overcome rainfade and other issues. Looks like they convinced the FCC that using one or two of the 46 transponders would be enough to qualify as a Ka sat to keep their license.

The main advantage of Ka band is that with two slots they could provide all the broadcast stations in HDTV (about 750 stations per slot). Note that this would require multiple spot beam satellites in each slot.

So, the question comes up if they can use these frequencies or not. The power requirements may be too great and too expensive at this time (having to launch 6 satellites per slot for example)

[Richard King]

Nice crash course. Very interesting reading.