Category: Antennas

CHA MPAS Lite – SWR Analysis

I decided to do a quick and simple SWR analysis of my Chameleon Antennas CHA MPAS Lite today.

NOTE: This is only in the VERTICAL configuration.

Using a Rig Expert AA-35 Zoom and the antScope 2 software, I ran through a few scenarios that I’m posting here for my reference and yours.

The antenna was setup in my backyard in a vertical configuration. I unspooled exactly 25 feet of counterpoise per the manual (marked with electrical tape for repeatability), laying it on the ground.

The entire length of the included coax was also unrolled and laid out on the ground. I did note initial higher SWR readings with it coiled and with a shorter length between the antenna and the analyzer.

Let’s start with a full range reading. This is the end to end range that the AA-25 Zoom can handle, which is 60kHz to 35MHz.

The vertical bands represent the US amateur radio bands from 160m – 10m

We can then run through each band, one by one, zooming in on the SWR ranges that the analyzer reports. Note the wide portion of each band that is covered by the SWR regardless of it being >= 1.5. We do not see large dips that start and end with the band edges.

160m

The overlapping colors represent multiple runs that I did on this band, playing with the placement of the counterpoise wire

80m

40m

30m

20m

17m

15m

12m

10m

Confusion

Upon getting the band by band results, I started scratching my head because the SWR readings that I was getting was different than what Chameleon reports in their user manual.

In some cases better, in others worse.

I decided to then run the AA-35 Zoom against my Hustler 4BTV Vertical antenna which I have for my permanent antenna installation at home.

Hustler 4BTV analysis for comparison

Everything lines up exactly like I expected for the 40/20/15/10 meter portions, so I am chalking up my CHA MPAS Lite readings to one of two things; environmental factors such as location, etc., or difference in meters being used from Chameleon and myself.

In either case, Chameleon does state in their user manual that:

The CHA MPAS Lite requires a wide range antenna tuner or coupler on some bands…

Page 3 of User Manual

In other words, this is not a resonant dipole that you hang in a tree and then go – it is a toolbox sort of antenna that performs quite well across multiple amateur bands, but requires some tuning depending on what band you’re using.

Conclusion

For reference, here is what they published for SWRs in a vertical configuration vs what I got, with green and red representing better or worse than advertised respectively:

FrequencyChameleon’s SWRKD0HBU’s SWR
1.94.53.7
3.73.32.9
7.12.02.8
10.11.82.8
14.11.72.1
18.11.21.5
21.11.21.5
24.91.62.2
28.52.02.6
There are a lot of variables that can affect an antenna and this is just a snapshot of one deployment in one area using one analyzer. I do intend to try the same deployment with my nano-VNA to see how the two compare.

If anyone knows what I should try different to improve on the above, please let me know in the comments.

chameleon antenna mpas lite

made for the harshest conditions and it shows

Macbook Air for scale (not included)

I just received my MPAS Lite from DXEngineering.

Pros:

  • Super quick setup – from start to finish was perhaps 2 minutes for the vertical configuration (oh yeah, this thing can be setup multiple ways)
  • Sturdy – I don’t have any other antenna that has hardware as beefy as this thing is
  • Resonant (!?) – To my complete surprise, though it shouldn’t have been had I read the manual – I got fairly low SWRs on most of the bands I checked, and my x5105 could tune the rest

Cons:

  • Length – The 17′ whip compacts down to about 2 feet or so, which means it sticks out the top of my GR1. I’m trying to figure out how I want to handle packing this thing so that I don’t have the whip get snagged on things, etc. Perhaps bring a bigger pack? Any suggestions?
  • Heavy – This one I’m going to caveat with two points; this thing is sturdy and has few parts, so from a weight perspective it is about on par with the other portable verticals that I own, and given the few parts that need to be kept track of, I don’t think weight is that big of a deal. It probably equals out with my other verticals, but definitely outweighs my dipoles.

We tend to tout the latest rig that costs hundreds or thousands, but frown on any antenna that isn’t made from $6 speaker wire. Speaking as someone who has built <insert insane number here> antennas from all kinds of cheap parts, and found them to be incredibly effective, there is nothing wrong with that. I’m just saying that sometimes investing in all the components of our radio setup is important.

How does it compare to my Buddistick or my Super Antenna MP1? I spend all kinds of time fiddling with both of those when I setup in the yard or field. In all the years I’ve owned my Buddistick, I’ve never been able to get the little mini-banana clips to tune the same way each time. The MP1 has a card that you use to line up the tuner on the coils, but that is ballpark and I still play with it until its good.

This thing is unpack, stick in the ground, unroll 25 feet of counterpoise, hook up the coax (included), and go. Per their manual, and backed up by my SWR meter, it is <2.0 on 30, 20, 17, 15, and 12 meters. It is also (in the vertical configuration) 1.8-1.9 on 40m. The manual says 2.0 – and as you can see I got better than that. The lower bands (60m and lower) are 3.0+.

Bring a tuner for those.

If you go with the end-fed inverted “V” configuration, then the numbers are even better starting out for the lower bands. Some of the upper bands like 17m and 12m do go above 2.0 though, with 40m around 3.0.

This thing solved for the majority of cases where I’m taking my KX3 or my x5105 out to play radio. For my MTR4B v2 or kit builds, I will probably stick with a resonant dipole hung in a tree (no tuners on those).

Did a quick RBN call to check propagation. As you can see below with 5 watts and the MPAS Lite, 929 miles (1490km) to one spot, and 1287 miles (2071km) to another isn’t bad from my backyard. And that is between a chain link fence and our home with aluminum siding.

This is my second Chameleon Antenna product, and I think they’ve hit a sweet spot between portability, durability, and ease of use. These are not built in a garage somewhere, but are made for the harshest conditions and it shows. It comes with a price tag, but consider that you’re investing in something that is made for being used, packed up, used again, packed up again, ……