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NEW CHA F-LOOP 2.0 from Chameleon Antenna is NOW AVAILABLE!

Discussion in 'Amateur Radio News' started by KI6TRA, Apr 30, 2017.

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  1. AK5B

    AK5B XML Subscriber QRZ Page

    As a strong proponent of STLs (small [electromagnetic] transmitting loops) I am glad to see that this manufacturer is trying to step up the game by using a solid aluminum element (albeit in two pieces which isn't so good) and the construction quality appears to be on the better side than most/all of the other commercial loops out there (with two major exceptions; the high-end Cirro Mazzoni STLs from Italy and VE3UK's TIG-welded loops from Canada).

    On the other hand, I am again saddened by the erroneous claims that the manufacturer makes about their "magnetic field" properties and efficiency which may well give rise to false expectations to many new or unaware hams in the process.

    Indeed, small transmitting loops that are well-made with the best construction practices can give surprisingly good performance and are a godsend for us that live in HOA situations or must operate portable---but everything comes at a price and not necessarily that price is paid in dollars or Euros or what-have-you. One cannot cheat the laws of physics!

    To get optimum performance one must use a vacuum variable capacitor and a continuous radiating element with as few soldered or welded connections as possible. Using any less than these optimum methods results in that the efficiency and transmitting performance will suffer greatly.

    The main radiating element should also have as large of an O.D. as feasible and also be close to 1/10th wavelength diameter as possible, too---which is beginning to get large at 20M and below, e.g., 5 feet for 20M and about double that for 40M; I use a 7-foot loop for 40M that can handle 600 watts and even then, it just begins to cut the mustard when conditions are good. Yes, I know, dx and reliable regional contacts can still be made with 3-foot loops on 40 meters and above---but it gets more and more difficult the more compromises one makes.

    I also realize that this Chameleon doesn't pretend to be ideal or optimum in the true sense of the word and that the targeted market is probably the low-power digital crowd where something like JT65 can get through on a wet shoestring---but I still think prospective users of any STL design do their homework before plunking down lots of hard-earned money for a compromised commercial version that almost purports to be the Holy Grail.

    I do hope that buyers of this antenna achieve good results and that the company continues to make further improvements in its designs---but with a finicky antenna design to begin with that is a task often better achieved by someone willing to invest time and resources in building in his own once a good understanding of how and why that they work---and what it takes to achieve good results is fully comprehended.

    For those not familiar with STLs and possibly wonder what I am going on about---please read Leigh Turner's (VK5KLT) excellent 32-page treatise for a fuller exploration of this fascinating antenna here:
  2. OH8STN

    OH8STN Premium Subscriber QRZ Page

    I don't have the F-Loop 2.0 yet, but like all the gear I review, I'm looking forward to taking it apart to see what it's all about.
    The original F-Loop (and I imagine this one too) is set up like a modular system. You've got a basic kit which was 60?/40-10m. Add the double loop kit (which was included in the original) to get 80m. There is also the F-Loop plus (included all of the basic kit, double loop for 80m) aluminum radiator kit. I have the original F-Loop plus in the attic above my shack on the remote tuner rotator which works well for me.

    The breakdown size of the basic F-Loop is pretty good. I only take the basic or double F-Loop to the field, although I did do RaDAR Challenge April 2016 mobile with the plus model. It's also self-supporting to sit on a table, bench, desk or can be tripod mounted if needed.
    The thing is, it's designed in the way that considered how the operator would work with it. So imho, usability was engineered into the design. Looking at the math, there could be better performing loops, either homebrew or commercial, but nothing easy to setup and work with. Definitely the F-Loop is the most well thought out loop I've worked with.
    The specs written in this thread seem to be meant for those familiar with the F-Loop philosophy, and can be confusing for those new to it. I think more effort focusing on the philosophy, options and specs, minimising the long marketing text, would help people understand the methodology.

    My hope for the updated F-Loop is even smaller breakdown size, and perhaps the various main and coupling loop options like the latest P-Loop 2.0.

    I've done some amazing work with the original F Loop, and I can't wait to get the update.
    Hope this helps.

  3. N8NN

    N8NN XML Subscriber QRZ Page

    According to the specs, I can improve my signal by one to two s-units by using a 1/4-wave vertical. Portability comes at a price. If a loop is the only way to get on the air, the CHA F-LOOP 2.0 is a solution. Being limited to 10 watts CW and an antenna one or two s-units below a vertical is a real challenge to "being on the air".
  4. W4OP

    W4OP Ham Member QRZ Page

    Please tell us why is the H field better than a non-magnetic loop antenna? In free space all antennas have an E/H ratio of 377 Ohms. Do your antennas not follow this?
    What does Q resonance of 17KHz mean? Is this the 2:1, 3:1, -3dB bandwidth? Your statement tells us nothing. I would also challenge the phrase of "most efficient". I know of another commercial loop that is less expensive, extremely well built and has higher efficiency.

    Dale W4OP
    Last edited: May 2, 2017
    AK5B likes this.
  5. K4WBF

    K4WBF Ham Member QRZ Page

    I have the first version of it and absolutely love mine. These are great for restricted community's and apartments. The RTR add-on is a great addition for remote tune and turning.
    OH8STN likes this.
  6. KI6TRA

    KI6TRA Ham Member QRZ Page

    The CHA F-LOOP 2.0 is modular and can be equipped with the Booster Kit which creates a 48" diameter magnetic loop. It's the same Booster Kit used for the CHA P-LOOP 2.0:

    The CHA RT-RR (Remote Tuner - Remote Rotator) can also be used with the CHA F-LOOP 2.0


    - C
  7. OH8STN

    OH8STN Premium Subscriber QRZ Page

    Dale, I don't want to inject myself into this constant fight you have with other manufacturers , but. I made a conscious choice between your loop, and the F Loop. It wasn't because your loop was more efficient or less efficient. It was because:
    1. From my perspective, more time is spent attacking competitors, rather than showing the operator why we should get behind your product.
    2. I can't find any good videos from your company or distributors showing setup, tear down, field deployment, ...
    3. Your loop seems to be well designed, but designed for the desk, backyard or picnic table, not the field. (Simple but well produced introduction videos could dispel that belief)
    4. I could not find details on breakdown size and weight.
    5. I hate the constant trolling (and so do my subscribers)
    Of course efficiency is important to field operators, especially at QRP power levels. Equally important are:
    • How simple it is to set up the loop
    • What kind of tools are required
    • How easily can be carried
    • Are there any fiddly screws and nuts to deal with during deployment, making it difficult if one has to wear gloves
    • Is a loop only what it is, or can its capabilities be expanded e.g. Adding a remote control and platform for remote tuning and rotating, optional larger main and coupling loop for greater efficiency, ...
    • If it's damaged in the field, can it be field stripped and repaired by the operator
    I'm definitely no chameleon Ponyboy! All of the products that I feature on my channel, are given the same care and attention, no matter who they come from.
    Like I told you, Steve from Alpha, and Carl from Chameleon, operators don't like this constant negativity between companies. That's why I blocked your comments on YouTube. If your product or anyone else's is as good as they say it is, they could use their energy to produce informative videos and articles with full HD images, so operators could decide for themselves, if that particular product fits their requirements. Requirements is actually the key! No operators should take the word of someone who has a commercial interest in a product. Whether or not the product is good for the operator should be based solely The Operators requirements, and the products ability to meet those requirements.

    Last edited: May 2, 2017
    KM6NJQ, W6QY and WU3U like this.
  8. W4OP

    W4OP Ham Member QRZ Page

    Hi Julian,
    First, let me answer the trolling comment. I am a regular contributor (technical) to the antenna forums, and it is very hard to miss the insufferable ads that chameleon invades this and the eHam forum with. That stuff belongs in the new Products forums and paid ads.

    My argument is that some manufacturers of antennas clearly have little knowledge of electromagnetics. They have proven this over and over. Calling their feeds Faraday feeds when they are not (and not knowing that a Faraday feed on an STL has no advantage), telling people that directivity and efficiency are related, not knowing how to use even an on-line calculator, let alone to do the rather simple math to evaluate efficiency, saying that 1 loop diameter above ground is sufficient. This all misleads the public, when they should be able to trust the manufacturers to give real facts.
    LNR does not abuse forums intended for technical discussion for their own advertising.
    Had you contacted them, they would have provided you with all the information, and more that you require.
    To answer a few questions though:
    Costs less
    No tools required.
    The loop has a custom round carrying case with back straps- unique in the industry.
    No fiddly screws
    Does not require an optional larger loop because it is already higher in efficiency than the others- write me I'll give you the real numbers.
    The LNR already has more capability- it does 60M (efficiently) and 6M, has a tuning scale, comes supplied with 2 mounting methods, adjustable feed and with a hybrid network that yields the best overall SWR of any of the loops.
    Repairing by the operartor depends on his skills.
    At Dayton's FDIM , you will see our remote tuning with features others don't have (stall indicators, waterproof etc) at hundreds of dollars less than the company you go with.

    I apologize if my comments to the group seem rude or harsh- but some expect real data and feel that manufacturers should be held to a higher technical standard.
    Here is an example; on the chameleon site it lists the F loop as having 14.9% efficiency. Using their own SWR curves and doing the math, it comes out to 1.7% efficiency. Some might say that is misleading.
    That same page lists all of the disadvantages of a 4' loop- this was before they discovered that our 4' loop outperforms their loops. I see we won them over at least in that area.
    Excuse me for asking questions, but I can't seem to get answers that are correct.
    BTW, I have no financial interest in this product.

    Dale W4OP
    OH2FFY and AK5B like this.
  9. AA5CT

    AA5CT Ham Member QRZ Page

  10. WU3U

    WU3U Premium Subscriber QRZ Page

    Please share the real numbers here with the group. Your confidence in the difference has me intrigued. There should be no reason as to why that can't be posted publicly especially if it is accurate.
    W6QY and OH8STN like this.
  11. KI6TRA

    KI6TRA Ham Member QRZ Page

    Let me help you out with that and you’ll be doing it yourself!

    Copy the following calculator on your computer.

    The calculator was designed by Steve Yates AA5TB. He’s a staff level Electronics Engineer at Lockheed Martin Aeronautics in Fort Worth for more than 20 years. He spent all his career in RF fields.

    Enter the following dimensions, measurements and numbers into the calculator:

    CHA F-LOOP 2.0 Basic Kit:

    Loop Diameter (34.059") or 2.83825’ & Radiator Diameter (0.404")

    CHA F-LOOP 2.0 15M to 40M Boosting Kit which is the same for the CHA P-LOOP 2.0:

    Loop Diameter (48") or 4’ & Radiator Diameter (0.404")

    CHA F-LOOP Plus 2.0

    Loop Diameter (36") or 3’ & Radiator Diameter (1")

    A magnetic loops that is larger than 36” in diameter isn’t very suitable for indoor uses because they’ll have tendencies to interfere with just about everything. It’s usually very hard to find enough clearance indoor to fully deploy them properly. But they’ll work great in your yard or at your camp site. We provide another coupling loop with the boosting kit because it maximize the ratio between the coupling loop and radiator thus maximizing performance and low SWR.

    Constantly remind yourself that the best people in any field are usually the people who receive the most criticism. The scale of criticism you encounter is proportional to the impact your work creates.

    - C
  12. W4OP

    W4OP Ham Member QRZ Page

    Efficiency is always worst on the lowest band. So 40M was chosen. Instead of using my own data, I will direct you to Owen Duffy's site. Owen is a brilliant mathematician: analysis 2.0 loop analysis W4OP loop

    Bottom line W4OP loop +4.7dB stronger. Efficiency 2.0 loop= 0.953% efficiency W4OP loop= 2.84%

    I guess they stopped making the aluminum radiator loop. The last data I had for it was that it was 10dB down from the W4OP loop. But there were numerous versions, so....
  13. AA5CT

    AA5CT Ham Member QRZ Page

    Sometimes, though a physicist is needed; do not bet that OD's word is the last word, and note particularly too under what conditions he may state his (most often) "mind experiment" or 'paper drill'. It would be re-assuring if OD could conduct an actual 'test' (carefully conducted experiment) in the field to validate his asserted 'paper' (modeled) results. Like, actually comparing two antennas' performance against each other using some mode that lends itself to that sort of test scenario, like WSPR.
    AK5B, OH8STN and KI6TRA like this.
  14. KI6TRA

    KI6TRA Ham Member QRZ Page

    “The loop conductor diameter is determined by the desired loss resistance due to skin-effect, and choices can range from modest 6mm copper tubing to large bore 100mm copper or aluminum tube. Commonly used conductor diameters used to construct a magnetic loop are 20mm and 32mm soft copper tube. Heavy wall thickness tubing is not required as the RF current flow is confined to the conductor surface due to the skin-effect. Note that the radiation efficiency is not related to the loop size. Loop antenna efficiency is determined by the conductor tube diameter and its electrical conductivity.

    Page 19

    “In comparison to a vertically mounted / oriented loop, the bottom of the loop does not need to more than a loop diameter above ground making it very easy to site in a restricted space location. There is no significant improvement in performance when a small loop is raised to great heights; all that matters is the loop is substantially clear of objects in the immediate surrounds and the desired direction of radiation! Mounting the loop on a short mast above an elevated roof ground-plane yields excellent results.

    Page 19

    “Aluminum works well in magnetic loop antennas. Yes, pure copper is a little better, but in multiple conductor magnetic loop antennas, there may be difficulty getting a copper loop to support its own weight. Structurally, aluminum is a lot better. Just make the conductors bigger. The choice of aluminum alloy can be important. Some aluminum alloys have excessively high resistivity figures, with 6061-T6 alloy having about the lowest resistivity of the commonly available aluminum alloys. The "architectural aluminum" sold in hardware stores can be used to build a magnetic loop antenna, but the resistivity of the various alloys sold under that name is typically high, and it should probably be avoided. The various copper alloys used in wire, tubing, and pipe sold at hardware stores frequently has a resistivity that is actually higher than that of 6061-T6 aluminum alloy. With this in mind, you will save money and likely achieve better performance with your magnetic loop using 6061 aluminum alloy.”

    Aluminum 6061-T6 is what we're using in our CHA F-LOOP 2.0 Plus version.

    - C
  15. W4OP

    W4OP Ham Member QRZ Page

    You are out of your league here Carl. Because you cannot do the math, you have to rely on other's work.
    Loop efficiency is defined as the loop's radiation resistance (Rrad) divided by the total resistance(Rt).
    Rt= Rrad + ground losses + resistive losses in the radiator ,the capacitor and all connections.
    For a given loop, let's assume (as we change the diameter) that the ground losses remain constant as do the capacitor losses and the connection losses.
    In fact, it is easier if we just put the loop up high where ground losses are negligible.
    What will change is the Rrad and the resistive losses in the loop conductor as it is changed in length.
    Resistive losses in the loop material are proportional to length. Double the length, the resistive losses double.
    The radiation resistance however, is proportional to the square of the area. Area is proportional to radius squared.
    OK so far? Let's take a loop of X diameter and double it to 2X. The resistive losses double because the length of the radiator double..
    Rrad goes up 16X (the area is doubled and Rrad is porportional to area squared).
    So let's pick some numbers typical of a 2' and a 4' loop of 3/8" copper tube. Since the connections remain the same and cap remains the same, we'll just look at the resistive losses of the radiator loop= Rloss.
    For the 2' loop we have Rrad= 0.8mOhms and the conductor losses= 44.1mOhms for an efficiency of 1.78% (.8/(.8+44.1)
    For the 4' loop we have Rrad= 12.2mOhms (16X) and the loop resistive losses = 88.365mOhms (2X) for an efficiency of 12% 12.2/100.565), or 6.75X more efficient than the loop half its diameter.

    If loop diameter did not make a difference- why do small loop builders strive for the largest loop diameters that they can handle/support??

    As for the 1 loop diameter above ground being sufficient, that fallacy can be proved with NEC 4 modeling and in the field by observing bandwidth vs. loop height. I again refer you to Owen Duffy:

    Dale W4OP
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