yet another antenna question

[KK4ELO]

i have an nmo mount antenna on my truck. it was a uhf p.s. 1/4 wave. i replaced it with an antenna that was originally an 84" whip..( have no idea what it was). i cut it down to the 1/2 wave length of 38 1/2" for 146mhz. will this do some good for my vx-150, or do i need to go 1/4 wave?

 

[rfradioconsult]

Nope, a half-wave antenna presents a very high VSWR and needs a base impedence matching network to match the 50 Ohms that is expected st the antenna.

 

[KK4ELO]

ok, thanks. so should i go ahead and cut it down to 1/4 wave then?

 

[rfradioconsult]

That would be my suggestion, even with a impedence matching network your gain would be about 2 dB not enough to provide much performance improvement.

 

[KK4ELO]

ok, thanks rf. ill cut it down tommorow.

 

[LtDoc]

Before you start cutting, try this. Make the first cut at around 57 - 59 inches, then check to see if the SWR is acceptable. If it is, try it for a while and see if it performs to your satisfaction. If not, then cut it down to around 19 inches.
- 'Doc