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COMPACtenna 2m/220/440: Theory & Design Video

Joined
Jun 30, 2006
Messages
7,352
Location
So Cal - Richardson, TX - Tewksbury, MA
#2
I'm very curious about the COMPACtenna and will probably get one to test out. However, whenever Dr. Jack opens his mouth I have to wonder if he has any schooling on antenna theory at all. I believe his has a medical PHD and I think he only had a tech license until last year.

I also have one of his Super-M Ultra base antennas and its got nothing I can find over a regular R/S type Discone. It claims a frequency range to 6GHz but at 900MHz its nearly 10dB down from a small Discone rated for 300MHz on up.
 

iMONITOR

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Premium Subscriber
Joined
Sep 20, 2006
Messages
6,158
Location
MACOMB, MI.
#3
I'm very curious about the COMPACtenna and will probably get one to test out. However, whenever Dr. Jack opens his mouth I have to wonder if he has any schooling on antenna theory at all. I believe his has a medical PHD and I think he only had a tech license until last year.
I'm not smart enough to judge him but if he's trying to sell this to everyone, he should describe it in laymen's terms. That's 21 minutes and 14 seconds of my life I'll never get back!
 
Joined
Jun 30, 2006
Messages
7,352
Location
So Cal - Richardson, TX - Tewksbury, MA
#4
I understand what he is saying and it has merit, but I don't think the spacing provided within the mechanical confines of his design allow for much if any diversity reception. I live in and around a bunch of hills and have not seen any advantage with my Not-so-Super-M Ultra compared a regular Discone in the same location.

I'm not smart enough to judge him but if he's trying to sell this to everyone, he should describe it in laymen's terms. That's 21 minutes and 14 seconds of my life I'll never get back!
 

cbehr91

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Joined
Jun 22, 2010
Messages
261
#5
There's also this video comparing the COMPACTenna to a very common dual band Diamond on receiving various ham repeaters in LA. On 2m, other than at one very specific point in a tunnel, the Diamond dual bander consistently beat it. UHF reception, though, actually seemed quite decent.
 
Last edited:

cbehr91

Member
Premium Subscriber
Joined
Jun 22, 2010
Messages
261
#6
I'm very curious about the COMPACtenna and will probably get one to test out. However, whenever Dr. Jack opens his mouth I have to wonder if he has any schooling on antenna theory at all. I believe his has a medical PHD and I think he only had a tech license until last year.

I also have one of his Super-M Ultra base antennas and its got nothing I can find over a regular R/S type Discone. It claims a frequency range to 6GHz but at 900MHz its nearly 10dB down from a small Discone rated for 300MHz on up.
There are several different models of COMPACTenna now. I actually wouldn't mind trying the shortwave model. My curiosity got the best of me and I ordered one of the original V/U/7/800 ones a couple years ago. On an NMO ground plane kit it sucked for rail reception. As a mobile it was much better -- about the same as a 1/4 wave whip with some slight variations.
 
Joined
Dec 19, 2002
Messages
15
Location
Bedford, TX
#7
Tried out the COMPACtenna for a couple of days, couldn't really tell any difference... especially in a the DFW metro area, and it was too obtrusive on the Dodge Challenger. Went back to using Larsen 2/70 short whip. I'll keep the COMPACtenna as part of my field ready stuff.
 
Joined
Jun 30, 2006
Messages
7,352
Location
So Cal - Richardson, TX - Tewksbury, MA
#8
Got my 2m/220/440 Compactenna today and did a quick check of receive levels using an Icom R8600 in dBm meter mode. I used an Austin Metropolitan tri band as a reference, which is simply a resonant 1/4 wave on 2m, 220 and 70cm and about 19" tall.

The antennas were used on the same NMO mount at the rear bed toprail of a pickup truck, which has very poor ground plane. A reading was made on various repeater output freqs on 2m, 220 and 79cm and antennas were quickly swapped while receiving the same repeater. Repeaters were coming in from various directions, some line of sight and some blocked by hills.

The numbers below are how much better or worse in dB the Compactenna is over the Austin. -2 would be the Compactenna being 2dB worse at that frequency and a +2 would be the Compactenna is 2dB better than the Austin.

2m,
0
+1
0
0
220MHz
-3
-4
-2
-8
70cm
-7
+3
+8
0
-2
-8
+2
-12

I find this very interesting. On 2m it looks almost a wash with a slight edge to the Compactenna, otherwise both antennas were performing about the same. On 220 the Compactenna was consistently worse than the Austin by 2 to 8dB. On UHF its all over the place with slightly more stations coming in weaker and to a greater depth of weaker than the Austin, but overall they might actually be close with an edge going to the Austin.

Did I mention this is very interesting? Especially comparing a 7 1/2" tall antenna to a 19" tall antenna. All this testing was done within minutes of receiving the new Compactenna. I need to do more testing with a mount that is centered on my roof and in an area clear of hills, etc, but at least I have some initial info that is fairly positive for this expensive little (and fat) antenna.

I'm also a little concerned with the aluminum threaded portion that mates with the NMO mount. I fear it will corrode over time if left on the vehicle and in the rain. Handling the very lightweight antenna doesn't give you the warm feeling that you spent your money well, but time will tell on the performance.
 
Joined
Feb 28, 2019
Messages
57
#9
Something to keep in mind is that when reducing the "size" of an antenna you will always reduce how well that antenna performs, both transmit and receive...
 
Joined
Jun 30, 2006
Messages
7,352
Location
So Cal - Richardson, TX - Tewksbury, MA
#10
Not always. You can shorten an antenna quite a bit with a capacity hat on top and not affect performance in any way. The Compactenna is something different and I'm not sure its inventor knows the exact science behind it.

Something to keep in mind is that when reducing the "size" of an antenna you will always reduce how well that antenna performs, both transmit and receive...
 
Joined
Feb 28, 2019
Messages
57
#11
Sorry, but if you reduce the size of an antenna, assuming you start with a 1/4 or 1/2 wave, you really will have less "performance" from it than the full sized version...'at's a fact Jack'. There will be a lessening of its measurable performance. That lessening may not be readily apparent, but its there. Then it depends on what you're expecting to start with and how you are using it. If a stubby fills your requirements then its fine...
 
Joined
Jun 30, 2006
Messages
7,352
Location
So Cal - Richardson, TX - Tewksbury, MA
#12
My name is not Jack and your statement is absolutely not a fact there Paul. Its all about where the current flows in the antenna. You can shorten a monopole some and make up for it a capacity hat. In this case the current on the antenna is redistributed and very favorable giving about the same radiation in a smaller package. Its a proven fact but this is not necessarily what is going on in the Compactenna.


Sorry, but if you reduce the size of an antenna, assuming you start with a 1/4 or 1/2 wave, you really will have less "performance" from it than the full sized version...'at's a fact Jack'. There will be a lessening of its measurable performance. That lessening may not be readily apparent, but its there. Then it depends on what you're expecting to start with and how you are using it. If a stubby fills your requirements then its fine...
 
Joined
Feb 28, 2019
Messages
57
#14
Cmdrwill may have more time in grade on -most- of these forums (glad you said "most"), but I have more time in pizza joints!!

As for time in antenna development, I concede. He also may have the same time in grade in construction and use of antennas as I do, I don't have any idea. And frankly, dont care.

It really helps when making comparisons that you know what you are comparing. Don't it?
 
Joined
Jun 30, 2006
Messages
7,352
Location
So Cal - Richardson, TX - Tewksbury, MA
#15
Its key to know what you are comparing and I did compare the 2m/220/440 Compactenna to a full size 1/4 wave whip on 2m and the 7.5" long Compactenna was at least equal to or slightly better than the 1/4 wave whip on 2m. That was a quick test receiving four different repeaters in different directions using both antennas on the same vehicle, same mount, same coax, etc. Receiver was an Icom R-8600 with S meter in dBm mode, which is very accurate. Is there anything else I should have known?

I will do more testing in the future when time permits but for now the little Compactenna on 2m is performing very well for its size.

Cmdrwill may have more time in grade on -most- of these forums (glad you said "most"), but I have more time in pizza joints!!

As for time in antenna development, I concede. He also may have the same time in grade in construction and use of antennas as I do, I don't have any idea. And frankly, dont care.

It really helps when making comparisons that you know what you are comparing. Don't it?
 
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