From where i could get an indoor aerial for my valve radio?

Dont bother with a net type antenna. It wont catch better signal. The best alternative will be a simple solid wire (preferably copper - any gauge as long as it can support its own weight) strung across about 10 feet or more. This is the simplest aerial for SWL. But be advised that indoor antenna is more prone to RF noise pickup and less sensitive than the same length of wire outside the walls.

If you are more flexible, have access to outside space and willing to experiment a bit then there are several other types of Antenna covering the normal Meter Bands. Do a google search for Inverted V or L type receiving Antenna. They are about as simple as you can get.

I doubt the net type aerial is still available. It was best a marketing gimmick.
My last net aerial (indoor) I bought was in year 2002 or 2003, I dont remember exactly. It was in Lamington Road area of Grant Road, Mumbai. However, in 2014 when I visited that area again, I inquired in every shop but none of them carry it anymore. It used to come in a plastic bag with a paper photo of Eagle inside it.
Someone can try somewhere in New Delhi near Chandni Chowk area.
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