Here's a couple resources to get started:
East Penn Traction Club (articles + PDFs)
Trolleyville Schoolhouse (many "how to" articles)
Carstens Traction Combo (two books)
Traction Planbook and Traction Handbook
Modeling Electrified Railroads (PDF-download)
Traction Guidebook (use eBay)
Conemaugh Road & Traction circa 1956
If you are looking at the prototype area I think you are, you're planning to put a spiderweb in the sky over a puzzle palace of fancy specialwork.
Murphy's paradise!!!
My own catenary motors are models of 1500VDC (not 11000VAC) prototypes. Even so, the contact wire (in 1:80 scale) comes out AWG #30 - WAY too light for one of my heavy motors with its pair of amp-hog open frame motors. #22 wire (the smallest I would consider for the service) ends up looking more like water pipe than contact wire. There's also the matter of wear - pantographs make sliding contact, and heavy traffic will guarantee that both pan shoes and contact wire WILL wear. Replacing pan shoes isn't much of a problem, but rehanging the overhead???
My solution, endorsed by armies of Japanese modelers, is to model 'virtual' catenary. The support structure, tensioners, substations and main power lines are present and accounted for - but the contact wires and their supporting cable aren't. Standard two rail power distribution/control means that the system can also handle steam and diesel locos without issues. Access to the track is infinitely improved, as is the ability to correct derailments if they occur. Even applying the Shop-Vac to the layout is less fraught with danger.
People HAVE built 'hot' catenary, and operated their models from it. I see no valid reason to emulate the feat when there's a less stressful approach available.
Chuck (Modeling Central Japan in September, 1964 - with steam, diesel and electric locos using the same tracks)
LION thinks that steel welding wire, the kind sold on spools might work for the wire, and for the brackets etc. You could use heaver 1/16" or heavier wire for the uprights. Even if you are mediocre or better at soldering you should be able to fabricate something.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS