electrical and communications engineering, etc.
Field Theory", Bo Thidé .
"Electromagnetic Fields and Energy", Herman A Haus and James R Melcher.
MIT Hypermedia Teaching Facility
Radio Antenna Engineering" by Edmund Laport (1952) .
"Antennas", J D Kraus. 1st edn. 1950 . 2nd edn. 1988 .
There is also a third edition (Kraus & Marhefka) but that will cost you money (it is however, well worth it).
"Transmission Line Formulas for Engineers". H B Dwight (1913)
Bell System Technical Journal (1922-1983).
A wealth of papers by now-famous authors: Shannon, Bode, Nyquist, Zobel, Schelkunoff, Pierce, Friis, etc..
[Update Feb. 2015. BSTJ articles can no longer be downloaded free from Alcatel-Lucent. An IEEE subscription is required. Volumes and papers can however still be obtained from Internet Archive].
BSTJ Paper Directory .
Listing of BSTJ papers with abstracts and alternative sources (such as Electrical Communication - see below) in some instances. Very useful for navigating the crude scans given by Internet Archive (see below).
Internet Archive .
Items obtainable from this site include the collected writings of Oliver Heaviside, Heinrich Hertz (English translations) and Lord Rayleigh. Also Maxwell's Treatise on E&M and Gray's absolute measurements in E&M. Complete volumes of BSTJ, 1922-1957 can also be downloaded (couldn't find 1955). Note that if you find youself reading the document using some horribly unergonomic online viewer applet, you are probably on the wrong page (any mention of Google is usually a warning sign). Search the site again for a genuinely downloadable version. Also some scans of old books are in colour. This increases the size of the file just to preserve the information that the paper has gone yellow. Sometimes there are monochrome versions in addition to the colour ones.
Absolute measurements in electricity and magnetism, Andrew Gray, 2nd ed. 1921.
This is the link to the Internet Archive page for Gray's magnum opus. The book is a monster (53MB for the b/w version) and can make pdf viewers jerky and sluggish. Hence it is useful also to have a document containing just the contents list and index:
Gray's Absolute Measurements (1921) Contents and Index (3.4MB PDF)
Electrical Communication (IT&T technical journal, 1922-1966).
From the COIT (Spain) server. General telecomms papers. Some BSTJ articles are reproduced here (or vice versa). To avoid downloading the entire archive (about 3GB), see:
Catalog of articles published in 'Electrical Communication' (3.2MB PDF).
Note that pages are missing from two of the scanned volumes on the COIT site. Complete versions of those journals have been assembled by Paul Coxwell and are available here:
Vol. 28 #4. Dec. 1951 , Vol. 33 #4. Dec. 1956 .
William Pickles (grandson of Lyndall C Pocock) has also made available a photograph of the ITT Technical Committee No. 5 taken in April 1958
Defense Technical Information Center .
HP Archive. HP journal, Seminar notes, application notes, Manuals, Boonton Radio Corp., etc.
The General Radio Experimenter. General Radio Journal 1920s - 1970s.
MIT Radiation Laboratory Series .
The 28 volume, 16000 page, write-up of the theoretical and practical devolpment of Radar and associated technologies during World War II. The content, now in the public domain, is of great historical interest, and much of it remains relevant.
Short-form contents lists are given here: Chapter headings and authors.
febo.com/RadLab . [Jefferson Lab].
febo.com offers complete 1st editions. These are freely downloadable as pdf files. Volume 25 lacks page 308 and has a duplicate of p306 in its place (looks like a printing error in the original book). Note that the pdf volumes on offer from Jefferson Lab. lack prefaces and contents pages and appear to be cut-down versions of the files available on the other site (same crops, same dirt spots).
Some complete volumes are also available from Internet archive (see above). Volumes 2, 5, 7, 9, 10, 11-2, 13, 18, 19, 20, 22, 23, 24, 26, 27 are definitely there in downloadable pdf form (search using the words 'Massachusetts Institute of Technology Radiation Laboratory series' in full. Also try the book title). These are 1960s Dover editions except for vol. 26.
tubebooks.org . Out of copyright technical books, particularly relating to the use and design of electronic tubes (valves) but also covering electronic and comms engineering, audio, radio, test and measurement, etc.
Google Patents .
US Patents are available as PDFs. Old patents (only available as images) can be searched by keyword using OCR. This is one area in whigh Google has actually made it easier for people outside the USA to access public domain documents. Also, the original page images are provided by USPTO, and so there is none of the trademark Google page corruption.
US Patent and Tradenark Office.
Veiwing patent images requires a 3rd party TIFF viewer plugin for your browser. For one option, you will be directed to the AlternaTIFF website; but beware. The download instructions are ambiguous and you can easily make the mistake of installing malware.
European Patent Office .
On the Transfer of Energy in the EM Field. J H Poynting, 1884.
NIST virtual library. NIST / NBS journals and papers.
Journal of the institute of electrical engineers of Japan (JIEEJ).
Many early articles are in English and can be downloaded free.
UrMel (Universal Multimedia Electronic Library) (German journals).
Note that when accessing articles in Annalen der Physik, the correspondence between the overall volume series and the editor-named volume series used in many ciations (Wied. Ann., etc.) can be found at physik.uni-augsburg.de/annalen/history/history.html .
e.g., to get from a Wied. Ann. (Wiedemann's Annalen) volume no. to an Ann. Phys. volume no., add 236, i.e., Wied. Ann. vols 1-69 are the same as Ann. Phys. vols 237-305.
Bibliothèque nationale de France, Gallica bibliothèque numerique.
Presse scientifique, including Comptes Rendus de l'Académie des Sciences 1835 - 1965.
arXiv.org (Cornell University Library) e-Print archive
Directory of Open Access Journals .
Scientific Research Publishing .
Journal of Electromagnetic Analysis and Applications .
Progress in Electromagnetics Research .
Bookboon.com. Free online textbooks .
Textbooks mainly written by British university teachers.
Tables of Physical & Chemical Constants. Kaye & Laby Online.
MOspace University of Missouri Repository .
Large download library, mostly chemistry and nuclear physics, but some mathematics and electromagnetics. Also a book on laboratory glass working.
Journal of Universal Rejection .