I needed a VHF and ideally UHF portable antenna. I had been assuming that meant lots of clever metalwork. But clever people have provided much more elegant solutions!
I made the coax cable based antenna for 2m and 70cm as described for RAYNET use by G3SMW. I believe the original designer was Frank Bremer, PA0FBK. This is made from approx 1.2m of RG58 coax, it has a small tuning stub then an RG58 feeder "tail" that includes a choke made by winding the coax into a coil. The antenna behaved as advertised, except I had to trim mine shorter than expected to get "good enough" VSWR on 2m. I achieved ~1.7:1; the antenna analyser suggests it is much better at about 139MHz. I don't have a calibrated way to measure VSWR on 70cm, other than to measure "3 bars" on the FT817 display. I threaded a nylon cord alongside the coax, that ends in a split ring type key ring.
For portable use I purchased a 6m fibreglass telescopic rod. These seem to be comonly known as "roach poles". Clever creatures, these fish. Mine actually came from a company called Wind Creations who sell them as freestanding poles for banners. A 6m pole, a 1m fibreglass ground spike to hold it upright and a bag cost approx £20 and weighs less than 1kg. The antenna fits into the same bag.
We were able to hand carry the whole lot up Butser Hill near home and operate /P for the first time today. It takes around a minute to erect the mast and antenna; it can easily be done single handed.