Chuck Daniels wrote:
"If part of the energy radiates back into the apartment is that really
dangerous or is it reasonably difused?"

The latter is likely. A dish focuses the microwave energy into a narrow
beam. It is like a spotlight. I seem to remember an output of -27dBm
(1/2 watt) which is puny. Your microwave oven likely produces 1000x more
power, and this is confined to a small volume.

Some of the dish`s beam may bounce back from the glass into the room,
but it loses 22dB in the first wavelength (about 5 inches?) back from
the reflection, and then 6dB more every time the distance doubles after
that. I wouldn`t worry or if I did, I would simply interdict the energy
with suitable screening.

Most of the power developed by the microwave transmitter should reach
the antenna or be shielded from direct radiation into the transmitter
room. A microwave oven leakage meter as sold in the past by Radio Shack
can be used to detect r-f around the transmitter, in the dish beam, and
reflected from the glass. They are cheap and they work.

A 1/2-watt transmitter is no big deal. When I started working with
microwave, the set consisted of (2) 0.1 watt klystrons. One was a
repeller modulated FM transmitter. The other was a local oscillator to
mix with the received carrier from the distant transmitter in a 1N23
silicon mixer diode to feed the I-F amplifier, limiters, and
discriminator.

The above radios could carry 600 or 1200 voice channels via frequency
division multiplex over a distance of 20 or 30 miles with few problems
and with high reliability.

We later got 5-watt klystron transmitters which were superseded by all
solid-state sets. Klystrons are no limitation to power. The most
powerful vacuum tube ever made was a klystron. Klystrons serve very well
in TV transmitters of enormous power. for line-of-sight point to point
service, high power is unecessary.

Best regards, Richard Harrison, KB5WZI