Mike,
I'm just finishing up work on WISPA's "Spectrum for Broadband" FCC
filing which is due today but hang with me for another hour or so and
I'll give you some background information about the FCC's TV White
Space rules as they currently stand. Once you have the context (full
view of the rules) I think you'll have a better view of why larger
(TV-type) antennas may be required for most future TV White Space
operators. No new understanding of physics is needed; just an
understanding of the current FCC rules, an understanding of what
channels may be available in what areas, and an understanding of why
you probably won't be able to simply pick a UHF channel and simply
"dwell" on it.
jack
Mike wrote:
Jack:
If your goal is to use VHF frequencies at 54 MHz then YES you will
need a large radiator! If your goal is to use UHF frequencies at
300, or 500 MHz, then NO, you won't need a 'TV sized" antenna. If
*MANY* 6 MHz wide allocations are made, then one would be stupid to
use a "do all" antenna for all frequencies. Maybe I am missing
something here. Perhaps a newly revised rules of physics?
Mike Hammett, I am not just trying to be contrary but am willing to
learn. UHF antennas are *MUCH* smaller than VHF antennas.
Mike
At 01:50 PM 10/23/2009, you wrote:
Mike,
You are correct. I'm deep into a final review of WISPA's Spectrum
for Broadband FCC filing right this minute (well, actually all
morning) but I plan to respond to Mike's points with more
information that he may not have about the TV White Spaces FCC
rules. I think once he has that additional information, he will
understand why your (and my) conclusion about needing a "TV-sized"
antenna is correct.
jack
Mike Hammett wrote:
The 30 meter antenna was misconstrued from the antenna height requirements.
It's required to be 10 meters or above for CPE use and no higher than 30
meters for AP use.
Why would a TV antenna or a TVWS antenna on the same frequency be any
different in size? Maybe some missing elements if your antenna only covers
part of the band, but a full band antenna should be roughly the same size as
current TV antenna. We have the use of 54 - 698 MHz (with the current rule
set, minus a few reserved channels).
Unless I'm missing something, which I doubt because Jack and I discussed
this at FISPA.
-----
Mike Hammett
Intelligent Computing Solutions
<http://www.ics-il.com>http://www.ics-il.com
--------------------------------------------------
From: "Mike" <mailto:[email protected]><[email protected]>
Sent: Friday, October 23, 2009 1:10 PM
To: "WISPA General List" <mailto:[email protected]><[email protected]>
Subject: Re: [WISPA] Holy cow!
Well the comments I've heard ARE ludicrous. Antennas as big as a TV
antenna, 30 meter antennas, and others.
Free space path loss is greater at 5.8 GHz than at 2.4
GHz. Substantially. Free space path loss at 700 MHz, or 600 or 500
is also SUBSTANTIALLY lesser than at 2.4 GHz.
Free space path loss is proportional to the square of the distance
between the transmitter and receiver, and also proportional to the
square of the FREQUENCY of the radio signal.
The FREQUENCY effect of the free space path loss is directly coupled
to the aperture of the antenna, which describes how sensitive an
antenna is to an incoming electromagnetic wave for which it is
resonant. Lower frequency equates to a larger aperture, and a larger
capture area for similar antennas, as compared to a much higher frequency.
If it is indeed a narrow band, then of course the chances of self
interference are there. The propagation characteristics of UHF for
fixed wireless are what cause me to want to "play" in this band
instead of some new allocation in the microwave regions. Think
through the trees, over the horizon, near line of site possibilities.
You also can't just reinvent the Yagi-Yuda or log periodic antenna
either. The sizes I stated for those frequencies ARE the full size
of an antenna, not some miniaturized or "rabbit ear" antenna.
Actually, I don't even think I'm arguing anything, just trying to
dispel a belief that white space antennas are these huge
monstrosities; they aren't.
For what it's worth, my personal record for distance on UHF is around
44,000 miles. REALLY!
Mike
At 12:20 PM 10/23/2009,Cameron wrote:
It is not "ludacrous". Sure you can receive with a small yagi or panel
or heck, even a set of rabbit ears. It's the uplink that will be the
major issue. If you are using small cells for coverage you can probably
get away with "smaller" antennas on the towers, but this will limit your
uplink capability if you are wanting a desktop type CPE or even a small
roof mount antenna. Small cell coverage like with uW freqs will have to
be carefully planned due to the propagation characteristics and the
potential for self interfernece on such a narrow band. It's not
impossible, just more complicated.
Cameron
Mike wrote:
At 704 MHz, a quarter wave is about 4 inches long. The driven
element of a Yagi would be about 8 inches long. They would be way
shorter than 30 meters, or what do you mean? Think about the 900 MHz
antennas you see but just a little bigger for the upper UHF white
space.
Ch 52 is 698 MHz. Ch 69 is 800 MHz. Some of the talk I've seen
about enormous antennas in the "white space" is ludicrous.
Give me ANY part of it and the radios to use it and I
will. Propagation would be superior to anything we're using now.
Mike
At 07:46 PM 10/22/2009, you wrote:
What equipment are they using? Did they have to do the 30 meter
antennas?
Scottie
---------- Original Message ----------------------------------
From: "Gino Villarini" <mailto:[email protected]><[email protected]>
Reply-To: WISPA General List
<mailto:[email protected]><[email protected]>
Date: Thu, 22 Oct 2009 12:05:22 -0400
IIRC, 6 mhz channels were proponed on the FCC RO, you could bond
them...
so with current OFDM technologies you can get 10 - 12 Mbps on a 6 mhz
channel.
Not bad for a NLOS, self install and mobile probability
Gino A. Villarini
<mailto:[email protected]>[email protected]
Aeronet Wireless Broadband Corp.
787.273.4143
-----Original Message-----
From:
<mailto:[email protected]>[email protected]
[mailto:[email protected]]
On
Behalf Of Scott Carullo
Sent: Thursday, October 22, 2009 11:58 AM
To: WISPA General List
Subject: Re: [WISPA] Holy cow!
My question is how fast can their internet go using tv whitespace?
Sprint
used to serve this area with an unutilized tv channel and it was
SLOW.
I
guess if you had nothing else but if it can't go one MB its not on my
radar
of concern. Actually in our market if you cant deliver 10-20MB your
not
playing the game.
Scott Carullo
Brevard Wireless
321-205-1100 x102
-------- Original Message --------
From: "Jack Unger" <mailto:[email protected]><[email protected]>
Sent: Thursday, October 22, 2009 11:49 AM
To: "WISPA General List"
<mailto:[email protected]><[email protected]>
Subject: Re: [WISPA] Holy cow!
See the attached Case Study and Press Release.
jack
Jonathan Schmidt wrote:
Dell, Microsoft Launching Broadband Net In Rural Virginia
Computer Companies Join TDF Foundation, Spectrum Bridge To Debut
Network
Using 'White Spaces'
John Eggerton -- Multichannel News, 10/21/2009 3:47:19 PM
Computer companies Dell and Microsoft are scheduled to join with
TDF
Foundation and Spectrum Bridge Wednesday to launch a broadband
network
in
rural Virginia, using the so-called white spaces between TV
channels.
House Communications Subcommitee Chairman Rick Boucher, who
represents
rural Virginia, is scheduled to be on hand as the companies host a
Webcast
with residents of an Appalachian community talking about how
wireless
Interent connectivity can change their lives.
The government is currently working on a national broadband plan,
including freeing up even more spectrum space for wireless
Internet.
Spectrum Bridge, a sort of Ebay for identifying available spectrum
in
secondary markets, launched a Web site in February to help identify
available open TV channels. The site can be used by wireless
Internet
providers to figure out whether there is enough spectrum in a
potential
service area to make it economically viable.
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