Why do you need a QFH antenna? won't any antenna work?
kch

If my calculations are correct, a 900 MHz QFH antenna will be approximately 1.5" in diameter and approximately 15" in length (height?), still within the hand held range, but somewhat large by today's stanards.

Higgler, IIRC, the QFH antenna has better circularity than a turnstyle crossed dipole type antenna.  Besides that, I too would ask why a QFH?

The QFH is circular off the end of the antenna, but not in other directions.  This would indicate that the antenna is meant for space communications.  The QFH receives vertical and horizontally polarized signals off the side equally poorly.  For terrestrial communications where faraday and spacecraft rotation are not factors, linear polarization would seem a sure bet...unless there are problems with multipath, then the 20 dB cross polarization(Left hand circular to Right hand circular) advantage would come into play.

 So, Erik, care to let us in on your need for CP?

I remain,

The Old Soldering Gunslinger