You are reading the rules correctly. While you can increase power with a wider channel, you also lose power on the receive side when the channel gets wider. Going from a 5 MHz wide channel to a 10 MHz wide channel you lose 3 dB in receive. So in that case the power increase is a wash due to the decrease in receiver signal. This is a power density thing. You will also limit your ability to move around if you have any interference as well when you have wider channels. 3 dB gain doubles your power and 3 dB loss cuts your receive signal level in half.
Thank You, Brian Webster www.wirelessmapping.com www.Broadband-Mapping.com From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Eduardo Sent: Monday, June 26, 2017 4:00 PM To: WISPA General List Subject: [WISPA] EIRP quick question Hi guys, We’re reviewing one of our links that is using RocketM365 radio and a RD-3G-26 in each end. The link is using 5MHz channel width. Here is the question: Checking the FCC regulation part 90.1321 I found that the limitation of the EIRP is defined as follow: § 90.1321 Power and antenna limits. (a) Base and fixed stations are limited to 25 watts/25 MHz equivalent isotropically radiated power (EIRP). In any event, the peak EIRP power density shall not exceed 1 Watt in any one-megahertz slice of spectrum. What I understand from this text is that for instance, if the link is using a 25 MHz channel then the maximum EIRP is 25 W, and if the link was 10 MHz channel width then the maximum EIRP is 10 W. If I’m getting it right, our link can still increase the bandwidth changing the channel width to 10 or 25 MHz and still comply with the maximum EIRP establish by the regulation. I’m interpreting the limitation correctly? Thanks, Eduardo Mejia Webjogger Internet Services www.webjogger.net
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