[TriLUG] Wireless access

Tue Sep 23 12:08:16 EDT 2003

Reginald,

I agree.  Good going Cisco.

Where is the page??

I want to see if this is applicable to my ham club
73's de Chip
KF4WBK

Reginald Reed wrote:
> Ralph,
> 
> In the link I posted, it shows what Cisco sells for antennas that do not
> require an FCC license.  I'm not an RF expert, but according to the web
> page, all of the antennas listed, including the dish with 21 dB gain are
> within the specifications for legal usage.
> 
> --Reggie
> 
> 
>>-----Original Message-----
>>From: trilug-bounces at trilug.org 
>>[mailto:trilug-bounces at trilug.org] On Behalf Of Ralph Blach
>>Sent: Tuesday, September 23, 2003 11:22 AM
>>To: Triangle Linux Users Group discussion list
>>Subject: Re: [TriLUG] Wireless access
>>
>>
>>
>>Reggie,
>>
>>A parabolic dish would work of course, but the problem is the 
>>that is has the wireless unit has not been qualified with a 
>>Parabolic by the FCC to work with these units. see slashdot
>>
>>And has a ham who follows the FCC enforcment, I would NOT 
>>want the FCC on my door step with an injuction.  It can get 
>>real messy reall fast.  With the new SAR requirements by the 
>>FCC, I only operate Low power so I dont have to prove I am 
>>below the SAR requirements.
>>
>>This is not about will it work and can it be made to work (It 
>>clealy can, and easily at that) but navigation of the FCC to 
>>allow you to do it.
>>
>>73's de Chip
>>kf4wbk
>>
>>
>>
>>Reginald Reed wrote:
>>
>>>If you are doing point to point over a long distance with 
>>
>>clear line 
>>
>>>of sight, I'd use something more directional than a Yagi.  
>>
>>I'd use a 
>>
>>>parabolic dish.
>>>
>>>--Reggie
>>>
>>>
>>>
>>>>-----Original Message-----
>>>>From: trilug-bounces at trilug.org
>>>>[mailto:trilug-bounces at trilug.org] On Behalf Of Ron Joffe
>>>>Sent: Tuesday, September 23, 2003 10:24 AM
>>>>To: Triangle Linux Users Group discussion list
>>>>Subject: Re: [TriLUG] Wireless access
>>>>
>>>>
>>>>On Tuesday 23 September 2003 10:10 am, Ron Joffe wrote:
>>>>
>>>>
>>>>>On Tuesday 23 September 2003 09:19 am, Ralph Blach wrote:
>>>>>
>>>>>
>>>>>>your yaggi might be able to get the Job done, but it would most
>>>>>>assuredly violate the FCC rules.  Remeber, that these radio's 
>>>>>>operate in the 2.4 ghz ham band and are Secondary users.  
>>>>
>>>>That means
>>>>
>>>>
>>>>>>that you will have to put up with Ham activities causing
>>>>>>interference.
>>>>>
>>>>>Would hooking up a Yaggi antenna directly to a commercial 802.11
>>>>>broadband bridge without amplification violate any FCC Rules?
>>>>>
>>>>>Ron
>>>>
>>>>Well I answered my own question. In the cisco link that 
>>
>>Reginald sent:
>>
>>>
>>http://www.cisco.com/en/US/products/hw/wireless/ps469/products_data_sh
>>
>>>ee
>>>t09186a008008883b.html
>>>
>>>It states:
>>>
>>>" In Point-to-Multipoint systems, the FCC has limited the 
>>
>>maximum EIRP
>>
>>>(effective isotropic radiated power) to 36dBm. EIRP = TX 
>>
>>power + antenna
>>
>>>gain. For every dB that the transmitter power is reduced, 
>>
>>the antenna 
>>
>>>may be increased by 1dB. (29dBm TX, +7dB antenna = 36dBm 
>>
>>EIRP, 28dBm 
>>
>>>TX, +8dB antenna = 36dBm EIRP).
>>>
>>> The Cisco Aironet Bridge transmitter power is 20dBm, which 
>>
>>is 10dBm 
>>
>>>lower than maximum. This then allows the use of antennas up to 10dB 
>>>over the initial 6dBi limit, or 16dBi.
>>>
>>> In Point-to-Point systems for 2.4GHz systems, using directional 
>>>antennas, the rules have changed. Because a high gain antenna has a 
>>>narrow beamwidth, and
>>>therefore the likelihood is high that it will cause interference to
>>>other 
>>>area users. Under the rule change, for every dB the transmitter is
>>>reduced 
>>>below 30dBm, the antenna may be increased from the initial 
>>
>>6dBi, by 3dB.
>>
>>>(29dB Transmitter means 9dBi antenna, 28dB transmitter means 12dBi 
>>>antenna). Because we are operating at 20dBm, which is 10dB 
>>
>>below the 
>>
>>>30dBm level, we
>>>can increase the out antenna by 30dB. However Cisco has 
>>
>>never tested,
>>
>>>and 
>>>therefore is not certified with any antenna larger than 21dBi."
>>>
>>>So I read this to mean that using a cisco aironet bridge, I 
>>
>>should be 
>>
>>>able to legally use up to a 36dbi Yaggi antenna.
>>>
>>>Ron
>>>
>>>
>>>
>>>
>>
>>
>>-- 
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> 
> 