After G7RQD read some interesting articles on the web on hentennas, M0PCR (M6PAR at the time) got together one winter's night in 2010 to try our hand at one. The hentenna was invented by Japanese amateurs, with 'hen' being the Japanese for strange. It is perhaps named so as it is vertically polarised when laid down in what you would have thought was a horizontal plane. Essentially its a full wave loop that is commonly used on the 2m and 6m bands.
Following the measurements on WA0ITP's website (see http://www.wa0itp.com/hentenna.html) we set about constructing a pair of hentennas for the 2m band from some lengths of 13mm copper pipe (some of which was salvaged in true amateur radio style!). With the use of G3YSW's antenna analyser the prototype loop was optimised for 145 MHz.
At present the hentenna sits in an outbuilding as an alternative 2m antenna for local natter when I'm outside the main shack. It certainly performs that task well compared to a slim jim that I made for that purpose. G7RQD's I believe sits in his attic shack and also gets occasional use. To finish off the hentenna I would like to weather proof the feed point as the black tape that I used will certainly not see off the British weather. Perhaps a job for the winter!
Why not have a go? See http://www.hamuniverse.com/n5nns4elhentenna.html for a 4 element 2m hentenna!
73 Peter, M0PCR
Edit: Club member Graham, G8ZNK, discovered some interesting directional variants of the Hentenna on DK7ZB's web site.