You don't hear about dip oscillators or noise bridges much any more. In the last 10 or 20 years the antenna analyser has emerged as the all-in-one must-have instrument for the serious antenna experimenter.
They are certainly handy. You connect an antenna, dial up a frequency on the analyser and you will get an indication of how it presents as a load, including its resistance and reactance. Better analysers have a display to show everything in graphical form. You can buy or build them.
The cheaper analysers have had somewhat mixed reviews so it seems to be a matter of getting what you pay for. The more practically inclined may be able to save by building one. DDS VFO modules and cheap microcontrollers, specifically the Arduino, have revolutionised their construction. Here's some ideas that could be handy:
* AB1ZO homebrew antenna analyser
* Cheap antenna analyser by Electronics Lab
* No frills antenna analyser (video)
* YD1CHS poor man's antenna analyser
* Tenna Dipper another poor man's antenna analyser