Can someone determine the power output of this antenna?

Thread Starter

ThirtyWest

Joined Jul 15, 2017
140
I'm doing some work on a project at work--having trouble interpreting the data.

This antenna has NA listed for power output.

http://www.antennasearch.com/sitestart.asp?sourcepagename=antennachecktxreview&getpagename=pgtxdetail&cmdrequest=getpage&ipos=55&isubpos=1&strtxtype=micro&unique_system_identifier=3693204&location_number=1

If you look it up at the FCC it shows 57.8dm, with a beamwidth of 3 deg and a gain of 35.3dBi.

https://wireless2.fcc.gov/UlsApp/UlsSearch/licensePathsDetail.jsp?pageNumToReturn=1&licKey=3423091&keyPath=415256


Through some materials given I would show 57.8dm EIRP as (57.8/1.64) => 35.2dBm ERP, and then => as 5.2dBw.

1. Using this online calc I found, would these numbers be proper for the ERP in watts? (using 5.2dBw and 35.3dBi)

http://mykit.com/cq/inf_data/dBWattsERPEIRPCalculator.htm

It doesn't seem to be working backwards to an EIRP value that I started with on the FCC site.

2. As an aside, is this how companies normally list the power output of their antennas when registered? Seems more cryptic than it needs to be.

3. Is there a good source to learn how dBi is determined? I understand that no 'additional' power is being used but rather the antenna is ignoring a greater deal of the sky with a 3 degree beam.


Thanks for the lookover and patience.
 

Delta prime

Joined Nov 15, 2019
431
Hello there. :) FCC does that on purpose a little trick I use is look up the call sign . If local use your RF service monitor that's 100%. By the way the Only gain of an antenna you can trace back to the actual power source would be in reference to dbm which would mean a millivolt reference into the antenna.
 

Papabravo

Joined Feb 24, 2006
14,253
For starters, Antennas do NOT output power. Antennas take the power they are given from the transmitter via the feedline and they radiate the power they are given period. To suggest otherwise would imply that you are involved in some overunity process. There is a theoretical antenna concept called an isotropic radiator. That is a fancy way of saying that this isotropic radiator takes the power it is given and radiates it equally in all directions. Now different antenna geometries can change that radiation pattern so that it conctrates more of the given power in some directions and less in other directions. The units referred to as dBi stand for "dB with respect to an isotropic radiator". So if you have a 3 element yagi and it gives 12.6 dBi in the forward direction it just means that is has taken whatever power was delivered and directed most of it in a particular direction and less to the sides and rear. To get a complete picture of what is going on you need two pictures one is azimuth which is looking down on the antenna from overhead to see where RF energy is being directed and the elevation to see the angle of departure from the ground. It may seem counter intuitive but horizontal antennas actually interact with the ground to send the RF energy into ionosphere as the Earth curves away underneath the wavefront.
 
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Thread Starter

ThirtyWest

Joined Jul 15, 2017
140
@ Papa. I know they don’t output. It was my intention to use the emitter They just use a convention that puts the values on both.

@ Delta. Why would FCC do that? And what monitor do you use?

@Externet thanks for that link description.

I did use the call sign through the ULS at FCC if that helps.

WQQE326
WQVR483
 

Papabravo

Joined Feb 24, 2006
14,253
@ Papa. I know they don’t output. It was my intention to use the emitter They just use a convention that puts the values on both.

@ Delta. Why would FCC do that? And what monitor do you use?

@Externet thanks for that link description.

I did use the call sign through the ULS at FCC if that helps.

WQQE326
WQVR483
I apologize for the conclusions I drew from your statement. I was trying to help sort out the source of your problem. If you are interested in how they come up with these numbers you might want to check out EZNEC. It is a software simulator that lets you enter a geometry and it gives you the radiation patterns in azimuth and elevation.

https://www.eznec.com/eznec.htm
 
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Thread Starter

ThirtyWest

Joined Jul 15, 2017
140
I apologize for the conclusions I drew from you statement. I was trying to help sort out the source of your problem. If you are interested in how they come up with these numbers you might want to check out EZNEC. It is a software simulator that lets you enter a geometry and it gives you the radiation patterns in azimuth and elevation.

https://www.eznec.com/eznec.htm
oh no worries. This isn’t my wheelhouse. Ramping up and learning is a forte of mine—hence projects.

I don’t have a service monitor but I’m checking out those mentioned above.

If the receiving antenna has the same beam width how does that relate to its ability to radiate ‘information’ outward?

I can understand the directionality of the emitter. Not so much with the antenna. My guess is there are secondary or tertiary antennae there that distribute the inbound information?
 
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