Question about "mystery" Pine Mountain radio site above Azusa

[AM909]

... The license does not show TX output power, only the antenna EIRP (as 70.9dBm). According to this converter, that would be 12.3 kW in what I presume would be the tightly focused beam path. But jeez, isn't that a touch high? I can understand punching through rain fade (the link is in the Ku-band range). But wouldn't 12.3 kW at 11 GHz cook anyone who got in the way to a crisp? I must be trying the conversion incorrectly...

Calc is correct. MDR-8711 11 GHz transmitter w/amp is +29 dBm, minus a couple dB feed loss, and adding a +44 dBi 6' dish yields +70.9 dBm EIRP.

 

[merlin]

Calc is correct. MDR-8711 11 GHz transmitter w/amp is +29 dBm, minus a couple dB feed loss, and adding a +44 dBi 6' dish yields +70.9 dBm EIRP.

Your numbers are right but your guestimate of TX output power, you are talking about 800 Miliwats. After the gain of a 6 foot dish it would be like 35.00 watts EIRP. for a 30 mile link, that is about average.

 

[AM909]

Your numbers are right but your guestimate of TX output power, you are talking about 800 Miliwats. After the gain of a 6 foot dish it would be like 35.00 watts EIRP. for a 30 mile link, that is about average.

? I think I got the dish gain from a real product datasheet, but it's confirmed by this calculator, which gives +45 dB for a 2 m diameter dish at 11 GHz. With 3 dB transmission-line loss +29 dBm + 45 dB - 3 dB = +71 dBm = 12.6 kW.

FSPL for the 15.3 km path is -137 dB. If the RX antenna is also a 2 m dish, with 3 dB transmission-line loss, you get -24 dBm at the RX, which seems like a lot. What's the real RX level in practice? where is the calc wrong? Where is the 11 GHz part of the TX and RX, i.e. before getting up/down-converted to something with more reasonable transmission-line loss?

 

[prcguy]

? I think I got the dish gain from a real product datasheet, but it's confirmed by this calculator, which gives +45 dB for a 2 m diameter dish at 11 GHz. With 3 dB transmission-line loss +29 dBm + 45 dB - 3 dB = +71 dBm = 12.6 kW.

FSPL for the 15.3 km path is -137 dB. If the RX antenna is also a 2 m dish, with 3 dB transmission-line loss, you get -24 dBm at the RX, which seems like a lot. What's the real RX level in practice? where is the calc wrong? Where is the 11 GHz part of the TX and RX, i.e. before getting up/down-converted to something with more reasonable transmission-line loss?

This is more correct. 71dBm is 41dBw or about 12.6kW ERP. There is an amount of rain fade at 11GHz so I would want at least 30dB of headroom and more is better if your license will allow it.