https://en.wikipedia.org/wiki/Beam_waveguide_antenna

The wiki article is short but I think it answers the question.

Non-"beam waveguide" antennas don't allow use of different receivers simultaneously. For example DSN 70-meter dishes can't receive Ka-band, but only X-band. They would require long operation of receiver change.

Also receivers and transmitters can require intensuve maintenance, for example loading of cooler.

Compared to them, beam waveguide can have X, Ka and other receivers, and the signal is "guided" to the specific receiver. No need for receiver installation every time. Upgrade of a receiver can also be done without disturbing of work of the dish and other receivers, I suppose (but have no proof for this).

So, BWG dishes are more complex but have huge operational benefits. A dish should be designed as BWG from the beginning, retrofitting of an existing dish to BWG can be impossible or too complex/expensive.

https://en.wikipedia.org/wiki/Beam_waveguide_antenna

The wiki article is short but I think it answers the question.

Non-"beam waveguide" antennas don't allow use of different receivers simultaneously. For example DSN 70-meter dishes can't receive Ka-band, but only X-band. They would require long operation of receiver change.

Also receivers and transmitters can require intensive maintenance, for example loading of cooler.

Compared to them, beam waveguide can have X, Ka and other receivers, and the signal is "guided" to the specific receiver. No need for receiver installation every time. Upgrade of a receiver can also be done without disturbing of work of the dish and other receivers, I suppose (but have no proof for this).

So, BWG dishes are more complex but have huge operational benefits. A dish should be designed as BWG from the beginning, retrofitting of an existing dish to BWG can be impossible or too complex/expensive.

https://en.wikipedia.org/wiki/Beam_waveguide_antenna

The wiki article is short but I think it answers the question.

Non-"beam waveguide" antennas don't allow use of different receivers simultaneously. For example DSN 70-meter dishes can't receive Ka-band, but only X-band. They would require long operation of receiver change.

Compared to them, beam waveguide can have X, Ka and other receivers, and the signal is "guided" to the specific receiver. No need for receiver installation every time. Upgrade of a receiver can also be done without disturbing of work of the dish and other receivers, I suppose (but have no proof for this).

So, BWG dishes are more complex but have huge operational benefits. A dish should be designed as BWG from the beginning, retrofitting of an existing dish to BWG can be impossible or too complex/expensive.

https://en.wikipedia.org/wiki/Beam_waveguide_antenna

The wiki article is short but I think it answers the question.

Non-"beam waveguide" antennas don't allow use of different receivers simultaneously. For example DSN 70-meter dishes can't receive Ka-band, but only X-band. They would require long operation of receiver change.

Also receivers and transmitters can require intensuve maintenance, for example loading of cooler.

Compared to them, beam waveguide can have X, Ka and other receivers, and the signal is "guided" to the specific receiver. No need for receiver installation every time. Upgrade of a receiver can also be done without disturbing of work of the dish and other receivers, I suppose (but have no proof for this).

So, BWG dishes are more complex but have huge operational benefits. A dish should be designed as BWG from the beginning, retrofitting of an existing dish to BWG can be impossible or too complex/expensive.