The Diamond RH-205 was very popular in the 1980s as the must have antenna for 2m operators.
- Length: 124 cm
- Collapsed: 23 cm
- Maximum diameter: 12 mm
- Weight: 90 g
It seems to function as a 1 / 4λ antenna when the rod is shortened to the shortest length, and with earth ground · SWR drops to about 1.2 at 150 MHz. When the rod is extended about 8 cm (about 2/3 levels), the bottom of the SWR becomes near 145 MHz.
I have several of these also as MFJ clones and work great for packet or aprs operation using older style hand helds (meaning they have a BNC antenna jack)