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 ÂŖ20 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.