D220R vs moon raker sky scan

[bearcatrp]

Has anyone done a comparison of these 2 antennas? I have the D220R. Looks like the moon raker would work better with the additional antennas. Appreciate any information on this. Thanks

Moonraker UK Limited 12-202 Moonraker Ltd SkyScan VHF/UHF Mobile Receive Antennas | DX Engineering

Free Shipping - Moonraker Ltd SkyScan VHF/UHF Mobile Receive Antennas with qualifying orders of $99. Shop VHF/UHF Mobile Monitor Antennas at DX Engineering.

www.dxengineering.com

 

[prcguy]

I think the comparison would be on par with comparing horse dung with a cow pie. Both have good points and bad points but you don’t really want to own either. I suspect the designers of each have no antenna engineering experience and they certainly don’t know what a Discone is or how it works.

Have you considered any other antennas that are actually good designs?

 

[bearcatrp]

Well, the D220R did ok out camping. Nothing stellar. Had it up 15 feet that helped. Have a better suggestion for wide band mobile? This would be for the R30 and the Lan IQ.

 

[prcguy]

Well, the D220R did ok out camping. Nothing stellar. Had it up 15 feet that helped. Have a better suggestion for wide band mobile? This would be for the R30 and the Lan IQ.

What bands/freqs are you most interested in?

 

[bearcatrp]

Have a wire for HF so above 25 Mhz. If needed to get 2, one for below 1 Ghz, the other above.

 

[prcguy]

Have a wire for HF so above 25 Mhz. If needed to get 2, one for below 1 Ghz, the other above.

Do you need VHF lo? For that there are really only two good choices, the old A/S MON series with micro choke thing or the Austin Spectra. I have several of each and prefer the A/S MON. For public service and amateur bands VHF through 900 there are many choices and one of my favorites is the COMPACtenna Scan III or LMR-1. You can compare many of them here:

Antenna range testing between multiband mobile antennas

I was going to add more to this package of information like a diagram of the setup, but I may never get to that so here its is as-is. I've been wanting to do an antenna range comparison of multi-band mobile antennas for some time and the recent purchase of a COMPACtenna LMR-1 compelled me to put...

forums.radioreference.com

The antennas in the range test are mostly current professional offerings for law enforcement/public service and can be quite pricy. They also have some of the best performance you will find in a very wide multiband model. You’ll notice none of them have any resemblance to the D220R or Moonraker.

 

[bearcatrp]

The Compac antenna scan III is interesting. Cannot find a web site for the A/S MON. I don't put antennas on my truck due to low clearance to my garage. I have a tripod and pole I take with with LMR 400 coax. Am surprised that little compact antenna is that good for you to endorse it. I like the small foot print that I can mount it on my truck while stationary at my rv park. That autin spectra is long but doable too. Will start looking at specs more before deciding. Thanks.

 

[bearcatrp]

This one, correct? Want to make sure before I order.

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

 

[prcguy]

This one, correct? Want to make sure before I order.

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

That’s it. If you look at the range testing the Austin Spectra is a bit lacking in the upper UHF and 800MHz range and in my opinion only useful if you need some VHF lo coverage. Otherwise the long out of production A/S MON series is a better overall performer.

Nearly all these multiband cop antennas struggle to come loose to 1/4 wave whip performance on any band, that’s just how it goes when you give up BW. Most are also close to 1/4 wave long on VHF being in the 16“ to 18” range but the COMPACtenna performance is right in there with most of them on VHF and it’s only 9.5” tall. The COMPACtenna also performs a little better in the UHF and 800/900MHz range.

There are a few cop antennas that were not available during testing and one is the newer PCTEL, sometimes rebranded by Motorola. It works at least as good as the others on VHF and 800/900 but UHF is down just a little. It’s a similar design to the Laird with fat base but missing the loading coil in the middle. The coil optimizes things on UHF at the expense of a little loss on VHF and they just let the longer VHF whip be a 3/4 wave on UHF which results in a squirrelly pattern. The reason I mention this antenna is you can find them new cheap on eBay. The last one I bought was around $19 with $25 shipping from Canada and they retail just under $200.

Price can be part of the shopping equation and although I’m a fan of the COMPACtenna, something close in performance for under $45 shipped is interesting compared to over $150. Here is one eBay seller that has the PCTEL/Motorola. New Motorola All-Band Antenna AN000131A01 | eBay If you were considering the COMPACtenna why not get both? I have a garage full of these the antennas and I’m still looking for more!

 

[bearcatrp]

Thanks for the reply. For now, will order the compact and check out the other ones. Thanks for your help

 

[bearcatrp]

Forgot to ask. Is the magnetic mount strong or half assed?

 

[prcguy]

Forgot to ask. Is the magnetic mount strong or half assed?

I've never used the magmount supplied with the COMPACtenna but I think its around 5" dia and plenty strong for the antenna size.

 

[bearcatrp]

Ok. Thanks.

 

[prcguy]

Ok. Thanks.

I’ve actually had a conversation with the guy who designed the COMPACtennas and we discussed mag mounts and how those antennas prefer to be near the edge of a car roof vs the center and how that affects VSWR. He did mention a preferred mag mount from his testing and I believe it would be of good quality.

 

[bearcatrp]

Since my truck barely clears the door going in, the only place I could mount it is on the front hood of the truck. What about the other options I saw like the compaccounterpoise. How well does that work?

 

[prcguy]

Since my truck barely clears the door going in, the only place I could mount it is on the front hood of the truck. What about the other options I saw like the compaccounterpoise. How well does that work?

If you can’t do the roof then the hood can work ok. Just be on the lookout for extra ignition noise on some vehicles.

The COMPACtennas in general need a ground plane adapter with radials bent downward to allow for matching at VHF. The radiating element is short and fat causing a lot of capacitance to ground and probably a very low impedance at VHF, that’s why they work well at the edge of a roof or trunk lid rather than the center with more ground plane. UHF/800 doesn’t seem to be as sensitive to ground plane.

I have several ground plane adapters I use with COMPACtennas and a few others around the garage and on travel. With the radials pointed down it can make a good tripod for sitting on a desk or bed when traveling to hold the antenna upright. I’ll post some pics of my home made adapters later today.

 

[prcguy]

If you can’t do the roof then the hood can work ok. Just be on the lookout for extra ignition noise on some vehicles.

The COMPACtennas in general need a ground plane adapter with radials bent downward to allow for matching at VHF. The radiating element is short and fat causing a lot of capacitance to ground and probably a very low impedance at VHF, that’s why they work well at the edge of a roof or trunk lid rather than the center with more ground plane. UHF/800 doesn’t seem to be as sensitive to ground plane.

I have several ground plane adapters I use with COMPACtennas and a few others around the garage and on travel. With the radials pointed down it can make a good tripod for sitting on a desk or bed when traveling to hold the antenna upright. I’ll post some pics of my home made adapters later today.

Here are some ground plane adapters I put together with the COMPACtenna in mind, although they work well with a few regular NMO whips. The mount on the far left is getting pretty extreme on the downward angle but still has a good VSWR on many antennas.

A more conventional ground plane with all radials in the horizontal plane will cancel radiation in the ground plane due to RF currents flowing equally in opposite directions. When the downward angle gets extreme like the left example I suspect it will behave more like a coaxial dipole with radiation off the radials resulting in a little gain.

The far left antenna is the COMPACtenna VHF/UHF/700-900 LMR-1 with NMO to N connector mount, middle is the COMPACtenna 2m/70cm with NMO to SO-239 mount and the far right is a PCTEL/Motorola VHF/UHF/700-900 with NMO to N mount.

 

[paulears]

All these antennas are sold with VERY scanty information on performance. Nowadays all antenna take five minutes to stick on an analyser and see where they perform well and perform badly - yet nobody ever does? The multi-whip designs just have a collection of individual resonant whips, and if their resonant frequency is an important one for the user, they're great, but a terrible choice for somebody else? A discone has the flattest frequency response and resonant frequencies, but no gain of course. Sticking that vertical on the top adds some extra performance at the resonant frequency of the whip, but does seem to cause some mismatching that alters the flatness of the discone performance. As I've said before commercial wide band systems - especially the really wide ones, use discones - very rarely the amateur 'clever' ones. If they worked well, the military would use those designs, but they don't. That's enough for me.

 

[Ubbe]

All these antennas are sold with VERY scanty information on performance. Nowadays all antenna take five minutes to stick on an analyser and see where they perform well and perform badly - yet nobody ever does?

Because it's pointless as a 50 ohm dummy load would then be the best antenna, but it isn't. You will have to somehow measure an antennas performance and not SWR.

A discone has the flattest frequency response and resonant frequencies, but no gain of course. Sticking that vertical on the top adds some extra performance at the resonant frequency of the whip, but does seem to cause some mismatching that alters the flatness of the discone performance.

The top whip use a bottom inductive coil that tries to isolate the whip from the discone at higher frequencies. That's why it usually is a low-vhf 40MHz whip to have that coil isolate more efficient at 118MHz and upwards. Discones are more or less flat at SWR but not performance wise as it degrades considerable at higher frequencies due to its vertical directivety shifts with the frequency.

If they worked well, the military would use those designs, but they don't.

I did my military service as a tech in the airforce, at that time every male over 18 had to enlist for a 7-12 month duty before they turned 22, and at their radio sites they only used discones to cover the 118-400MHz range that they used. It works well and are the only suitable omni antenna to be used in a 1:5 frequency range. When you go beyond that 100MHz-500MHz range are when you start to lose performance.

/Ubbe

 

[paulears]

I tend to agree, but there is a link between where resonance occurs and the impact on transmit and receive. I get what you mean about a dummy load, but The resonance plots do line up with the frequencies in question. A good example might be a dual band antenna for a hand held. The fact that many perform badly is often revealed in the plots, where the UHF performance at say, 435MHz is poorer than expected, and the analyser shows the resonance peak very sharp at 460MHz. A clue would be helpful. I have a quad band antenna that I discovered had an unexpected resonance at 89MHz - it turns out to be damn good at broadcast FM radio!