It doesn't matter if it's connected to an HT or some other radio, a "long wire", or probably more accurately, a random wire antenna can certainly be made to work. Since how that wire will be run/mounted will make a difference in it's usability, figure on being able to tune it in some way.
Also figure on providing a ground, or the 'other half' of that antenna, that's going to be a necessity. If nothing else, and equal length of wire laid on the ground can work. A typical HT uses the radio's chassis and the one holding that HT as it's 'ground', which is never going to be all that 'good'.
All kinds of choices for a portable antenna, guess it just depends on how big your pockets are...
- 'Doc
Some definitions;
Longwire: typically at least two wave lengths long at the frequency of use.
Randomwire: typically at least a 1/4 wave length long and more.
'Chunker': what you tie on the end of that wire/cord to throw something over something else.
'Chunkee': the one doing that chunking.
Frustration: typical state of the one doing that chunking or antenna using.
Expectations: what that @#$ antenna was supposed to do!