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Re: HYBRID QUADRATURE JH-6-4 or equivalent

 

Hi Hisami,
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Thanks for the response.
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On Mon, Apr 28, 2025 at 12:58 AM, hisami dejima wrote:
> Insertion Loss: 3.5 to 3.8 dB
Does the 3 in 3.5 to 3.8 dB mean 'diveded into two port'?
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Yes. If the coupler were completely lossless, insertion gain would be -3.0 dB to the 0 degree and 90 degree ports (another words, power split equally to each output port). This coupler only adds 0.5 dB and 0.8 dB of loss beyond that.
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Japan will be on holiday for about a week so difficult to buy parts.
I want to build it on a T37-2 core.
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I think you could implement the four inductors using T37-2 cores. You would need to match the inductances as close as possible to the ideal values. Here are the ideal values:

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L1 = 3.49 uH

L2 = 0.269 uH

L3 = 14.7 uH

L4 = 1.13 uH

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C1 = 340 pF

C2 = 26.9 pF

C3 = 1470 pF

C4 = 113.4 pF

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The 14.7uH inductor would require 60 turns which seems like a lot. Two inductors could be placed in series here if 60 turns is a problem.


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For fine tuning, do I just match the frequencies?
example, L1A 3.3uH, L1B 330nH and C1 360pF are 4.4 MHz
Or is there another guide?
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Matching the frequency basically sets the phase shift through a section.? The gain through a section is controlled by the ratio of L to C. Hence, tuning a particular part will effect both gain and phase. I would start by getting component values as close as possible to the ideal values given above. Note that you can tweak the inductance of an inductor implemented on a T37-2 core by pushing the windings closer together or further apart.

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Mark
AG5RT
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Re: HYBRID QUADRATURE JH-6-4 or equivalent

 

Hi Mark
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Thank you very much for the information.
Please tell me.
> Insertion Loss: 3.5 to 3.8 dB
Does the 3 in 3.5 to 3.8 dB mean 'diveded into two port'?
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Japan will be on holiday for about a week so difficult to buy parts.
I want to build it on a T37-2 core.
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For fine tuning, do I just match the frequencies?
example, L1A 3.3uH, L1B 330nH and C1 360pF are 4.4 MHz
Or is there another guide?
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73, Hisami 7L4IOU
Re: HYBRID QUADRATURE JH-6-4 or equivalent

 

On Sun, Apr 27, 2025 at 04:48 PM, Piotr, SP2BPD wrote:
Hi Piotr,
I understood.
Thanks for the addition.
73, Hisami?
Re: HYBRID QUADRATURE JH-6-4 or equivalent

 

Hi Piotr and all,
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Thanks for posting the Chris Smith article and the LTSPICE analysis.? Back in the 1990s I developed a circuit very similar to that described by Chris but with one major simplification: each of the four filter sections is reduced from four reactive components to two. Utilizing this simplification, I just completed and tested the prototype circuit described here:
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/g/loopantennas/files/AG5RT/90%20Degree%20Hybrid%20Prototype.pdf
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The biggest change since the 1990s is the much improved availability of tight tolerance inductors and capacitors at a reasonable cost. All the LC components I used in the prototype are stocked at Mouser and vary in price from $0.08 to $0.41. All capacitors are 1% tolerance.? All inductors are 2% tolerance.??
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I am very pleased with the measured results (see plots in the link).? Over the band 2 MHz to 32 MHz, I obtained the following:
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Maximum phase deviation from 90 degrees:? ? 5.5 degrees
Maximum gain imbalance: 0.22 dB
Isolation between 0 and 90 degree ports: 21 dB minimum
? ? Insertion Loss: 3.5 to 3.8 dB
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All measurements were taken using a nanoVNA.? I did some curve fitting in LabVIEW to obtain cleaner plots.? Note that no tweaking of component values was needed to obtain the measured phase deviation and balance.? Parts with the usual 5%, 10%, or 20% tolerance would have produced much worse results.? I think the parts mounted on an actual printed circuit board would yield even better results.
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Mark
AG5RT
Re: HYBRID QUADRATURE JH-6-4 or equivalent

 

90 degree hybrids with mulitoctave frequency are possible but this is the 21st century. . .
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Jim
thanks for the inspiration, however, things are not that simple. A hybrid analog coupler can be placed directly at two orthogonal antennas (e.g. small loops). Behind the coupler is a chain: amplifier, cable, receiver (two-channel, to its second receiver is fed the signal from the vertical antenna and its amplifier).
Now let's follow your line of thinking: Feed the signal from two orthogonal small loops to two mixers. But how to ensure that these loops are broadband matched (across the HF range, and perhaps even lower to LF) to the impedance of the cable. ?This task is usually fulfilled by amplifiers such as the LZ1AQ, Wellbrook, etc. However, introducing amplifiers also means introducing a gain difference between them, and this already affects the accuracy of angle-of-arrival measurements.
A simple analog solution allows accuracy of better than 5 degrees over a wide frequency range. I don't know if the inclusion of two amplifiers in the circuit won't cause more deviation.
I once wrote to Andrew Ikin asking if he could produce two reasonably identical ALA100LN amplifiers. His answer was short: "forget it".
These are my thoughts on a Sunday afternoon.
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Re: Coupling loop advice

 

Hi Victor

Copper pipe, it stays rigid, though coax works.

Re the main loop, that also should be copper pipe. Reason, losses, and if use coax and it moves/flexes then its out of tune and you will need to readjust cap.

Simon g0zen
Re: Coupling loop advice

 

One more question:
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is it better to make the coupling loop with coax (ie RG213) or copper pipe?
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Thanks.
Re: HYBRID QUADRATURE JH-6-4 or equivalent

 

Re: Coupling loop advice

 

The unshielded coupling loop is likely to produce the lowest losses.
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When using a toroid, especially on the lower frequency bands, a high permeability core material is required. These tend to be lossy, in addition, core saturation can also occur. This is because a small diameter core is required to achieve adequate coupling to the loop structure, and this in turn means that a very small core cross-section is carrying the majority of the flux.
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Regards,
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Martin
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On Sun, Apr 27, 2025 at 09:05 AM, V¨ªctor J. S¨¢nchez wrote:

At first I'll made an unshielded coupling loop so it's the easiest method althougt the toroid is an excellent alternative too.
Re: Coupling loop advice

 

Hi,
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I'm very pleased for the bunch of answers and advices you tell me. Thank you very much.
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At first I'll made an unshielded coupling loop so it's the easiest method althougt the toroid is an excellent alternative too.
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Thank you for all. Regards.
Re: HYBRID QUADRATURE JH-6-4 or equivalent

 

Hi Hisami,
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I've attached a new file: /g/loopantennas/files/NX0E_hybrid_coupler/loss_plot.jpg . V(n005) is the voltage at the source.
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The losses are not 9 dB but about 3 dB.?
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Kind regards
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Piotr
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Re: HYBRID QUADRATURE JH-6-4 or equivalent

 

Hi All,
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A friend told me.
this this type of Hybrid is often used in 4 square vertical systems.
for example as TK5EP.
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73, Hisami 7L4IOU
Re: HYBRID QUADRATURE JH-6-4 or equivalent

 

Hi Piotr,
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Thanks for the information and LTspice file.
The 9dB loss is a bit large, but the clean phase is wonderful.
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tnx & 73, Hisami?
Re: Coupling loop advice

 

Yes, this would work quite well.? In technical terms, its called a Rogowski Coil.? Uncle and amateurs have fed the base of a water fountain using a Rogowski coil as well as feeding trees.? I'[ve never tried it, but the theory is sound!

Dave - W?LEV

On Sat, Apr 26, 2025 at 7:28?PM Dan Clementi via <dan=[email protected]> wrote:
On Fri, Apr 25, 2025 at 07:25 PM, V¨ªctor J. S¨¢nchez wrote:
Hi, Victor.
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Not to derail the discussion too much, but the toroid coupling method shown in figure 32 of that link works very well indeed.
Not only is it mechanically very simple and robust, but you can also infer something about the parasitic resistance of your main loop and interconnect to the capacitor.? I.E. once you have the turns ratio for best SWR at resonance, you can calculate the total resistance loading the secondary side of the transformer and then subtract out the radiation resistance.
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Dan - K3GMQ



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Dave - W?LEV
Re: Coupling loop advice

 

On Fri, Apr 25, 2025 at 07:25 PM, V¨ªctor J. S¨¢nchez wrote:
Hi, Victor.
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Not to derail the discussion too much, but the toroid coupling method shown in figure 32 of that link works very well indeed.
Not only is it mechanically very simple and robust, but you can also infer something about the parasitic resistance of your main loop and interconnect to the capacitor.? I.E. once you have the turns ratio for best SWR at resonance, you can calculate the total resistance loading the secondary side of the transformer and then subtract out the radiation resistance.
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Dan - K3GMQ
Re: Coupling loop advice

 

Hi Dave

Snake oil..lol

Just dont make any improvement..good selling point though!

Simon g0zen, ex maker of 160/80m mag loops that can get into USA, Caribbean etc from UK ssb.. ( now live on Dartmoor.. as you know,( rsgb tech marconi T) no longer need a tx mag loop. Though I do still have it incase I end up end of life in a HOA.( put a bird box in it..its a modern art tree..!)

Regards.Simon
Re: Coupling loop advice

 

If you look at the physics of the "shielded" loop, you will rapidly realize it is NOT SHIELDED from the induced currents!? That's the whole reason for the gap at the top high-Z point, opposite the feed point and according to the reference diagram: "This will not work".

The use of the term "shielded" certainly connotes the physical appearance of the loop, but from an EMAG standpoint, it is totally in error.

Dave - W?LEV

On Fri, Apr 25, 2025 at 11:25?PM V¨ªctor J. S¨¢nchez via <vjosesan=[email protected]> wrote:
Hi all and thanks for accept me in the group.
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I'm building a magnetic loop antenna for TX and I slightly follow the instructions in and another sources. I've finished the main loop with the capacitor and its rotator and now I have to choose a coupling loop configuration. There are basically 2 variants: unshielded and shielded (aka Faraday loops). According to the link I've wrote I'd like to use the shielded F variant because it seems to be better cancelling E-fields in horizontal and vertical polarization. But there are some people that think both variants work the same.
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I'm in doubt with this. Any advice or experience?
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Thanks in advance. Regards.



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Dave - W?LEV
Re: Coupling loop advice

 

I would agree with Simon. Use an unshielded coupling loop and place an effective common mode choke on the feedline, and also on any control cables.
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Regards,
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Martin
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On Sat, Apr 26, 2025 at 09:48 AM, Simon wrote:

Unshielded..been there done it..dont waste time on shielded. Its not the antenna, its just the coupling to the antenna which has already received any noise. A common mode choke in coax by antenna would be good though.
Re: HYBRID QUADRATURE JH-6-4 or equivalent

 

OK. . .
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90 degree hybrids with mulitoctave frequency are possible but this is the 21st century. . .
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Buy a dual channel SDR receiver with matching "IF signal handling" chains and create the 90 degree phase shift in the "digital" local oscillator.
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For that matter add a third antenna element and think about a quaternion signal detector with three LO's and three parallel if stages.
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Jim/VEZ
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Re: HYBRID QUADRATURE JH-6-4 or equivalent

 

An addition:
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As you can see from the phase plot the deviation from 90 deg is less than 5 deg for the range: 2.4 - 37 MHz. The design can be easily scaled to another frequency range.
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But note: there is no constant phase difference between the input and outputs. Only the two outputs maintain an approximately constant phase shift between them.
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