COMPACTenna vs. Larsen Tri-Band

[emsflyer84]

Hey guys, I have a Larsen tri-band mobile antenna that I’m using now on a ground plane kit as my home base scanner antenna. Recently I’ve been reading about this:

COMPACTenna SCAN-III COMPACtenna Model SCAN-III NMO Mobile Monitor Antennas | DX Engineering

Free Shipping - COMPACtenna Model SCAN-III NMO Mobile Monitor Antennas with qualifying orders of $99. Shop VHF/UHF Mobile Monitor Antennas at DX Engineering.

www.dxengineering.com

and I was curious if anyone has any experience with it. I see claims online that it outperforms other NMO mount antennas, especially where there is no line of sight to the transmitter. I also like the form factor. I’d be interested in swapping out my tri-band Larsen for this COMPACTenna but only if it’s possible there is actually performance improvements. Just curious on the experts thoughts here. Thanks!

 

[vagrant]

Only you would be able to find out the difference because no one else has your exact setup and geographic location where you antenna is mounted. I have both of these antennas and my comparison would somewhat be meaningless for you, as I do not have them mounted the same way. I have nothing bad to say about either antenna, but they definitely are different.

If you want to improve your system, the antenna is the best thing to work on first and getting it high up into the air outdoors. Bigger is often better with antennas. Sometimes we are limited in placement, so the next help would be good quality coaxial cable, like LMR-400 and not a run that leaves you with too much excess coaxial cable. Next may be filters to reduce strong signal interference from FM broadcast stations, paging systems around 152 MHz and even nearby strong signal NOAA transmitters just above 162 MHz.

1. What problems are you having with your Larsen setup?
2. Are you curious about what you may be missing, or do you have too much noise with the signals you monitor now?
3. Also, what frequencies, or frequency ranges do you listen to, or wish to monitor?
4. What coaxial cable type are you using now, how long is the run and how high up is your antenna? Is it above your roofline?

 

[emsflyer84]

Only you would be able to find out the difference because no one else has your exact setup and geographic location where you antenna is mounted. I have both of these antennas and my comparison would somewhat be meaningless for you, as I do not have them mounted the same way. I have nothing bad to say about either antenna, but they definitely are different.

If you want to improve your system, the antenna is the best thing to work on first and getting it high up into the air outdoors. Bigger is often better with antennas. Sometimes we are limited in placement, so the next help would be good quality coaxial cable, like LMR-400 and not a run that leaves you with too much excess coaxial cable. Next may be filters to reduce strong signal interference from FM broadcast stations, paging systems around 152 MHz and even nearby strong signal NOAA transmitters just above 162 MHz.

1. What problems are you having with your Larsen setup?
2. Are you curious about what you may be missing, or do you have too much noise with the signals you monitor now?
3. Also, what frequencies, or frequency ranges do you listen to, or wish to monitor?
4. What coaxial cable type are you using now, how long is the run and how high up is your antenna? Is it above your roofline?

Thanks for the reply. Here’s the situation. I was using a Centerfire folded dipole tuned to 150-165 which is 90% of where I’m scanning. I was getting good range with this antenna. It has a 300 to 75 ohm transformer and a 60’ run of RG6 into a notch filter to take care of some strong data interference on a particular frequency that was bleeding through on weaker signals. The filter is attached right to the scanner via BNC (Whistler TRX2).

So that was working quite well as far as range. There were still frequencies that I wanted to get that would come in some days and not other days. Atmospheric maybe. But I was getting quite a bit of noise on certain freq’s with this setup. Sometimes, freq’s that would come in great most of the time would get staticy and fade out totally in the middle of a transmission. Then come back strong just as quick. It was strange.

So I changed to a Laird ground plane kit with a Larsen tri-band. Right away I noticed the signal was cleaner. And it SEEMED at first that range was improved too. Some signals that were weak with the dipole are stronger now. But then I noticed some freq’s that I could hear before (weak) are silent now. It seems like the ones that were the weakest before are now not coming in at all. Which really makes no sense because other signals are stronger then before. I can’t make sense of it. I guess it’s possible that those signals just seem stronger because they are cleaner and less noisy.

So I love the clarity of the Larsen and it seems to be a solid performer. But I think the range was better with the dipole overall.

So I’m just looking for ideas to increase range a bit but maintain a clean, clear signal. I may end up playing with the dipole again, rotating it on the mast, changing height, etc to see what happens.

 

[prcguy]

There is data and a chart in this thread that directly compares a Larsen tri-band to a COMPACtenna Scan III and another commercial multiband antenna. Each has its strong and weak points and for its size a COMPACtenna is a fairly good performer. You will not get night and day differences playing with antennas of similar size, if you want a big noticeable improvement you may have to go with separate gain type antennas for each band and combine them.

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

 

[jaspence]

I use a dual band ham version. I had a MFJ dual band 3.2/5.7 dBi gain 41 inch antenna on my old car, but it was too tall on my new car to go into the garage. I picked up a dual band Compactenna the year they were introduced at the Xenia (Dayton) Hamfest. It has worked as well as the standard whip and I can reliably reach the repeater from 25 miles on the 20W power setting of my FT-90R.

 

[emsflyer84]

Well, it turns out most of my signal and range issues are feed line based. I took a 3’ section of coax connected to my scanner on one end, and my folded dipole at the other end and just stood on my deck holding the antenna in my hand. I immediately starting hearing things I’ve never heard before. The signal was so strong. Transmissions that are typically hard to make out were clear as day. So I have some issues with my line from my scanner to my antenna it looks like. I’m ordering a single length 25’ cable which is the length I need. Right now I have a few lengths of cable pieces together to make the run, and it’s possible there was water intrusion at some point. We’ll try the cable replacement and see what happens.