Larsen TRI-Band VNA Sweep (Part Deux) + Laird Scanner and COMPACtenna SCAN III

[devicelab]

I have three different COMPACtennas here and they perform better than many other antennas that are larger.

Perhaps but you also need to consider the topography of your area. In my area with repeaters located on mountain tops these compromise antennas do not perform as well. I think if you are in a relatively flat location then the performance might be a little misleading. In these locations a simple 1/4 wave may seem magical. In my region these antennas can work OK but usually a 5/8 wave is needed for best performance to help cover the terrain gaps.

 

[prcguy]

I'm surrounded by 5,000+ ft mountains full of repeaters and the next group of them out are around 9,000ft with some repeaters up there. We also have flat land repeaters around here and some on modest hills and I have a 2m, two 70cm, 900 and GMRS repeater at my house to play with and range test.

In my testing against the popular Larsen tri band and Laird tri band, the COMPACtenna Scan III worked a little better most of the time, and its much shorter than the other antennas, and it costs about the same as the Laird I was using. The COMPACtenna is roughly the equivalent of a 1/4 wave on VHF but it slightly outperforms a VHF 1/4 wave and its only half the height.

The COMPACtenna is indeed a compromise, mostly for those needing an antenna shorter than what's typically available but it works surprisingly well under all conditions I've subjected it to. I don't often recommend a specific antenna unless it does really well in my testing and I have no problem recommending the COMPACtenna Scan III or the tri band amateur version. So far for their size and intended use of being a "compact antenna", I find no other antenna that outperforms them for their size at any price and I suspect I've tested far more antennas than most people on RR.

Perhaps but you also need to consider the topography of your area. In my area with repeaters located on mountain tops these compromise antennas do not perform as well. I think if you are in a relatively flat location then the performance might be a little misleading. In these locations a simple 1/4 wave may seem magical. In my region these antennas can work OK but usually a 5/8 wave is needed for best performance to help cover the terrain gaps.

 

[rgchristy]

I read all the posts on here that I could find, but couldn't see anything definitive that said one antenna was significantly better than the other. Remarks regarding the lack of or diminished ground plane caught my eye.

For my usage and the frequencies that I listen to, the Scan-III seemed to be the best option, especially since it is less obtrusive in an apartment window, as opposed to a standard antenna. I have found the reception to be excellent.

Fortunately, money was not a factor in the purchase. I have made many purchases at HRO before and have always found their recommendations to be quite good. Overall, I am very pleased about my purchase.

So they convinced you to spend 2x your money and boy you sure feel satisfied... well, there's one born every minute -- I suppose. ;o)

 

[prcguy]

Here is an actual field test with received signal levels between the COMPACtenna and two other popular tri band antennas. This was with all antennas tested in the middle of a vehicle roof where the COMPACtenna is not operating in its best surroundings. If you repeat the test with a compromised ground plane like the edge of a trunk lid or corner of a roof the COMPACtenna will work a little better.

Comparison, Larsen Tri-band, Laird WPD136M6C-001, COMPACtenna Scan III - 118 to 922MHz

Here is something I've been wanting to do for a long time but didn't have the COMPACtenna scanner version to test. Another RR member who shall remain anonymous purchased one and sent to me for testing (thanks vagrant!) so I spent some time yesterday running tests on these three antennas. The...

forums.radioreference.com

I read all the posts on here that I could find, but couldn't see anything definitive that said one antenna was significantly better than the other. Remarks regarding the lack of or diminished ground plane caught my eye.

For my usage and the frequencies that I listen to, the Scan-III seemed to be the best option, especially since it is less obtrusive in an apartment window, as opposed to a standard antenna. I have found the reception to be excellent.

Fortunately, money was not a factor in the purchase. I have made many purchases at HRO before and have always found their recommendations to be quite good. Overall, I am very pleased about my purchase.

 

[merlin]

I have the newer Nano VNA-H4 and calibrated, it tells me the same thing, just as accurate, as my $25,000 Agilant.
Better suited for antenna tuning and analyzing out in the yard (test range)
Can't beat it for the price.

 

[mmckenna]

I have the newer Nano VNA-H4 and calibrated, it tells me the same thing, just as accurate, as my $25,000 Agilant.
Better suited for antenna tuning and analyzing out in the yard (test range)
Can't beat it for the price.

Same here.
However, it's much easier to read the screen and use the controls on the Agilent. I'd go nuts trying to do that with the NanoVNA.

But, yeah, for home/hobby use, hard to beat them.

 

[nd5y]

Does a NanoVNA have the resolution necessary for tuning duplexers and cavity filters?

 

[mmckenna]

Does a NanoVNA have the resolution necessary for tuning duplexers and cavity filters?

Probably good enough for most users.
I'd not want to rely on it, and I'd not want to do it where my reputation was on the line.

 

[tweiss3]

Does a NanoVNA have the resolution necessary for tuning duplexers and cavity filters?

The NanoVNA has a set number of sample points (I want to say 100), so the more narrow you can keep your sweep, the better.

 

[vagrant]

I use a similar device and in my experience "Yes" for a simple UHF mobile notch duplexer, or a cavity filter. Much depends on the isolation dB and if the inexpensive analyzers can handle the depth of the cavity/filter and or notch duplexer. I confirmed the tune with an Agilent 8935 after first using the inexpensive analyzer.

When I tried with a Telewave 1484 VHF BpBr duplexer, "No". The sweep was just way off and hardly adjusting during a tune. After tuning with the 8935, the sweep was way off on the inexpensive analyzer after looking again.

Hmm...I happened to be tuning a Motorola T1500 UHF BpBr duplexer with the Agilent 8935 yesterday. I just put the small meter on it and it shows the pass and reject fine. The numbers are very close too. I am using an N2061SA vector impedance analyzer and I may trust it to tune the pass and reject on this T1500 if that is all I had. The actual numbers are close but not professional close. A watt meter with some power could tell you the TX loss after tuning to compare the dB.

I am unsure as to why it works on one duplexer and not with the other. I suspect the split difference to be one reason. There are probably other factors, but overall these inexpensive analyzers are very handy for amateur grade projects.

Does a NanoVNA have the resolution necessary for tuning duplexers and cavity filters?

 

[devicelab]

The NanoVNA has a set number of sample points (I want to say 100), so the more narrow you can keep your sweep, the better.

The NanoVNA-F V2 can do 201 points...