Roy Lewallen wrote
Don K wrote
John - KD5YI wrote
Rod Speed wrote

A receive antenna has no EIRP, it doesnt radiate any real power.

Actually, when properly matched, it radiates half the received power.

How do you get that?
If the receiver input impedance is matched to the antenna, all the
received power is absorbed. There is no reflection. There is no
radiation.

If the receiver matching is for optimal noise figure, there may be
some reflection and reradiation, but there's nothing pinning it to
be half the received power.

John is correct.

Nope.

A receiving antenna, when matched, reradiates half the power it receives.

Yes but that ISNT ANY REAL POWER in the EIRP restriction sense.

An impinging field induces current in the antenna. This causes radiation, just like the
current in a transmitting antenna. As it turns out, when the antenna is matched, the
amount of power radiated equals the amount of power delivered to the load, and that's
the best you can do.

Yes but that ISNT ANY REAL POWER in the EIRP restriction sense.

If you'd like a more in-depth and mathematical explanation, you can find it in any
antenna text, often discussed as "scattering".

Not relevant to the original point, any effect on the EIRP restriction.

If a receiving antenna did absorb all the impinging power, it would be a lot easier to
make a shield or a stealth aircraft.

Not relevant to the original point, any effect on the EIRP restriction.