I started “Pedestrian Mobile” around 20 years ago operating on 15,17, 20 and 40M SSB and in order to get really close to the sea I used to use a small 2-wheel lightweight easy to pull along trolley or cart this can be seen with me in the pictures.
The radio could quickly be removed from the cart when I can’t pull the trolley on the beach and is then carried in a “back-pack” as seen in the picture above; the RF power output was continually adjustable between 100mW and 30 Watts maximum.
DC power comes from a single 12 Volt gel battery inside the back-pack
and the antenna was a home-made top loaded vertical.
The transceiver is another modified Alinco DX70 powered by a 24Ah battery; alternatively a single 7Ah battery supplies the radio when carried in the backpack.
The antenna was a very lightweight home-made top loaded vertical about 3.5 metres long, this was tuned against the frame of the backpack or trolley, (whichever is in use) using a similar, but physically smaller ground tuning system as on the bicycle, and can be seen in the picture above on the right, it is the small yellow box below the antenna.
I also added digital voice recording to the pull along pedestrian mobile trolley, which enabled me to playback the QSO’s and manually enter them into my computer log when I get home.