mmckenna
I ♥ Ø
I had my analyzer at home with me. Since it's a nice day, I decided to play around with some various antennas, save the plots and do some comparisons. Since pictures are worth a thousand words, here they are:
This is a Larsen NMOQ cut for near the center of the 2 meter amateur radio band. Mount is a permanent NMO mount in the dead center on the roof of a Ford F150 crew cab.
Notice the wide bandwidth. This is where quarter wave antennas really shine. For interoperability uses, it's hard to beat. It's easy to get 2.0:1 SWR across a big chunk of spectrum.
Marker 1 is at the lower 2.0:1 SWR point. at 138.478MHz
Marker 2 is near the center of the 2 meter amateur band.
Marker 3 is at the upper 2.0:1 SWR point, 170.695MHz.
32MHz of useable bandwidth.
This is a Larsen NMO-150 5/8th's wave VHF antenna. Tuned for near the center of the amateur radio band. Same mount as above.
Compare the much narrower bandwidth. The 3dB of additional gain compared to the quarter wave comes at a cost. While 5/8th's antennas are useful for the added gain, they don't cover as much spectrum. Not an issue for someone who is purely using it for amateur radio use, and for a commercial/public safety user that is limited to a narrow band. For interoperability, maybe not the best choice.
Markers at set up like above. Upper and lower 2.0:1 SWR points and the center(ish) of the 2 meter band.
12MHz of useable bandwidth.
This is a Larsen NMOQ cut for near the center of the 2 meter amateur radio band. Mount is a permanent NMO mount in the dead center on the roof of a Ford F150 crew cab.
Notice the wide bandwidth. This is where quarter wave antennas really shine. For interoperability uses, it's hard to beat. It's easy to get 2.0:1 SWR across a big chunk of spectrum.
Marker 1 is at the lower 2.0:1 SWR point. at 138.478MHz
Marker 2 is near the center of the 2 meter amateur band.
Marker 3 is at the upper 2.0:1 SWR point, 170.695MHz.
32MHz of useable bandwidth.
This is a Larsen NMO-150 5/8th's wave VHF antenna. Tuned for near the center of the amateur radio band. Same mount as above.
Compare the much narrower bandwidth. The 3dB of additional gain compared to the quarter wave comes at a cost. While 5/8th's antennas are useful for the added gain, they don't cover as much spectrum. Not an issue for someone who is purely using it for amateur radio use, and for a commercial/public safety user that is limited to a narrow band. For interoperability, maybe not the best choice.
Markers at set up like above. Upper and lower 2.0:1 SWR points and the center(ish) of the 2 meter band.
12MHz of useable bandwidth.