Larsen NMOQ versus Larsen NMOWBQ

[mmckenna]

Had my spectrum analyzer with tracking generator home from work to check the antenna on my wife's truck.

Decided to shoot a Larsen NMOQ and a Larsen NMOWBQ for comparison.

The Larsen NMOQC is a 'field tunable' NMO mount quarter wave antenna. It's an NMO base with a thin whip. https://www.theantennafarm.com/cata...roduct_info&cPath=191_192_206&products_id=767

The Larsen NMOWBQC is an NMO mount wide band quarter wave antenna. It has a thicker whip, compared to the NMOQ, and has a spring at the whip base. Whip diameter and the diameter of the spring helps give it the 'wide band' nature. https://www.theantennafarm.com/cata...nfo&cPath=191_192_195_457_212&products_id=724

They are not tuned to exactly the same spot on the spectrum, so the valley of low SWR is going to fall at a different point. This not anything to do with the antenna design, but reflects on the whip length, where it was cut, and what section of the VHF band it was intended to be used on. Since I use commercial radios in my personal vehicles for both amateur and commercial stuff, I stick with Part 90 radios and usually tune the antennas somewhere in the middle between the 2 meter band and the section of the VHF LMR band I'm using at work.

Like my other posts on quarter wave antennas and discones, this isn't intended to sell you anything or reflect anything to do with radiation angles. I'm just sharing the screen shots to show the differences between the two antenna models.

Larsen NMOQC. Note, the #3 marker is off, so don't go by the SWR reading, but compare the trace to the wide band antenna below:


Larsen NMOWBQC:

 

[mmckenna]

Here's a Larsen NMO-150 5/8th's wave VHF antenna for comparison. Notice less bandwidth below 2.0:1 SWR.

 

[Reconrider]

No idea how to read these images but OH MY GOSH PRETTY PICTURES (lol)

 

[vagrant]

Interesting and thank you for the sweeps. Do you have a Larsen NMO150-450-800 you can plot?

 

[cavmedic]

No idea how to read these images but OH MY GOSH PRETTY PICTURES (lol)

The "M" indicates a marker or that numbered diamond you see. M1 = Marker 1 , M2 = Marker 2, etc
Across the bottom is the frequency span in which it is " scanning" and up the left is the SWR
So where the markers fall , on the left is the SWR, and at the very bottom of the display is the frequency of that specific indicated marker
.

 

[mmckenna]

Interesting and thank you for the sweeps. Do you have a Larsen NMO150-450-800 you can plot?

I don't. I'm happy to do a sweep of one if someone would donate it.

 

[KevinC]

Interesting and thank you for the sweeps. Do you have a Larsen NMO150-450-800 you can plot?

Larsen Tri-band antenna

Well, I've been running it the last few weeks here in the Sacramento area. It picks up all the repeaters great on both VHF and UHF. I have not really scanned 7/800 or even 900 on it yet, though I will when I get a new scanner. As expected simplex range greatly diminished. It really is great...

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