Re: Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos
Basically you are using a simple jig consisting of RF isolation transformer and voltage dividers 24/0.5 ohm.
My idea has been different based on a standard using a dummy antenna circuit recommended for use in testing broadcast receivers.
It was published old article by W.Swinyard in 1941 " Measurement of Loop Antenna Receivers" , where two coupled loop antennas were used for distances between them less than wavelength but greater than diameter of larger of two loops ( transmit or receive ).
I have been considering to construct a different jig/ dummy antenna circuit consisting of pi-type attenuator with unequal shunt arms - towards generating source 50 ohm resistor and towards antenna amplifier 2 ohm resistor or 0.5 ohm. Between the attenuator and input of amplifier under test to be included additional circuit that represents dummy loop antenna - series arms of fixed inductances, say 700 uH or more ( La/2 ) and shunt arm - fixed capacitor ( Ca ).
Regards
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Re: 2e0ero Magnetic Loop Antenna
Hi Sigi
Don¡¯t get angry, messages can lead to misunderstandings, ie I didn¡¯t know 80m etc..
I agree vertically oriented shorter dipoles work well. Assuming not too short which yours are not.
I still prefer verticals against good gnd plane, but thats here at new qth ( especially as neighbours have allowed me to put many 40m radials in their land ,) in East London for low bands a mag loop as that¡¯s all I could use..
Regards Simon
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Re: Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos
> was that the circuit you came up with after our previous discussions about how best to simulate a loop in the absence of a standard method ?
Yes.
> 1. Yes, between CH0 port of VNA shall be a fixed attenuator, say for 20 - 60 dB. However, it shall be Pi > > configured for balanced connection with a shunt arm - active resistor of value 2 ohms ( that resistor > > >> would > represent the loss of antenna ).
I am having problems visualizing the above circuit. Can you kindly post a circuit diagram?
As the inductance (L1-2=700 nH) and capacitance values also significantly differ from LZ1AQ's and Loudet's dummies, does its output impedance resembles G8JNJ's measured loop Z? Thanks.
My interpretation of G8JNJ's work is that the LPF is necessary even though it obliterates LZ1AQ's original intention of providing low Z input because it tracks the loop aerial's increasing Z with frequency. Without the LPF, the gain will be significantly reduced over 15-30 MHz (see graph "gra_sim gain @ LPF.jpg"). I brought up the issue of the LPF obliterating the preamp's low Z promise with LZ1AQ, but he reassured me that does not impair the amp performance
Thanks to all for the suggestions & feedback. :-) Brickbats are also welcomed!
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Re: Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos
For my loop preamp measurements, I use a jig between the VNA and the preamp, shown here:  - unbalanced to balanced transformer is now different, on T50-6 core, quadrifillar wound. Primary is 10+10T (center connection floating), secondary is 10T and 10T - jumpers to change the output between in-phase (for common mode suppression measurement) and differential. - Jumper outputs are connected to 24Ohm to 0.5Ohm dividers, serving as an attenuator. It mimics the loop impedance (somewhat, at least on the lower frequencies). This also results in a good S11 on the VNA side. No additional attenuator is used. LZ1AQ gives about +5dBm at the peak of the curve, no problem for NanoVNA. 73, Mike AF7KR
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Re: Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos
Hi Martin, ? Did you weigh the dummy circuit that I recommended besides using coupled loops in near field that you favour? ? Raphael ?
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From: [email protected] < [email protected]> On Behalf Of Martin - Southwest UK via groups.io Sent: Saturday, July 13, 2024 6:46 PM To: [email protected]Subject: Re: [loopantennas] Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos ? On Sat, Jul 13, 2024 at 06:04 PM, Raphael Wasserman wrote: LPF might be connected as well as based on actual situation FMBS interferers.
Hi Raphael,
I quickly tried Biastee's circuit, but it didn't work out too well for me.
I still favour my version, which gives results that are close to an actual loop, but perhaps still not close enough.
/g/loopantennas/message/19705
Regards,
Martin
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Re: Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos
On Sat, Jul 13, 2024 at 06:04 PM, Raphael Wasserman wrote:
LPF might be connected as well as based on actual situation FMBS interferers.
Hi Raphael, I quickly tried Biastee's circuit, but it didn't work out too well for me. I still favour my version, which gives results that are close to an actual loop, but perhaps still not close enough. /g/loopantennas/message/19705Regards, Martin
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Re: Urban HF Antenna Dilemma: LZ1AQ vs. M0AYF
On Sat, Jul 13, 2024 at 09:34 AM, Raphael Wasserman wrote:
Allow Files area to upload *.s1p touchstone file format ?
Photos only allows certain format files. I know of no such limits on the Files area. ? -- Steve Greenfield AE7HD
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Re: Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos
Hi Martin,
Also I noticed that schematic diagram of Biastee's having presented the loop antenna as a dummy load in order to run S21 test with VNA.
In my opinion, the layout should be changed differently:
1. Yes, between CH0 port of VNA shall be a fixed attenuator, say for 20 - 60 dB. However, it shall be Pi configured for balanced connection with a shunt arm - active resistor of value 2 ohms ( that resistor would represent the loss of antenna ).
--- |--------^^^^^---|------~~~~~~~~~~~~~~~~|----------->
R1=50 ohm R3 R2=2 ohm L1=700 nH = Ca<50 pF to amp under test
|--------^^^^^---|------~~~~~~~~~~~~~~~|------------>
GND R3=R4=10 ohm - 3Kohm L2=700 nH
2. Connect L1=L2=700 nH as series arms and an additional shunt arm with capacitor Ca<50 pF
3. The LPF might be connected as well as based on actual situation FMBS interferers.
Regards,
Raphael
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Re: 2e0ero Magnetic Loop Antenna
ahh no pictures as attachment ... grrrr
Am 13.07.2024 um 18:34 schrieb
Siegfried Jackstien:
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my
80m verson is 17m high (15m long with about 2m off ground) ...
where did i say its fullsize??
its a bit smaller as a quarterwave without cooking worms (almost
like an inverted groundplane) ... at least i do not need a mile of
wire below it
my property has the shape of a shark tooth (sharp triangle on
western end) ... means radials would lay on neighbours field
(absolute forbidden!!) ... playing around in mmana i found this
solution
see pictures
max current is not at the base but around halfway up (say 10m off
ground) and it works as good as a quarterwave if not better ...
with fewer wire needed
dg9bfc sigi
Am 13.07.2024 um 18:18 schrieb Simon:
Hi Sigi
Yes they work well. As long as can get bottom leg clear of gnd.
But abit impractical for low bands. Ie 40m high for 80m
Simon
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Re: Urban HF Antenna Dilemma: LZ1AQ vs. M0AYF
Steve,
Allow Files area to upload *.s1p touchstone file format ?
Raphael
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Re: 2e0ero Magnetic Loop Antenna
my 80m verson is 17m high (15m long with about 2m off ground) ... where did i say its fullsize??
its a bit smaller as a quarterwave without cooking worms (almost like an inverted groundplane) ... at least i do not need a mile of wire below it
my property has the shape of a shark tooth (sharp triangle on western end) ... means radials would lay on neighbours field (absolute forbidden!!) ... playing around in mmana i found this solution
see pictures
max current is not at the base but around halfway up (say 10m off ground) and it works as good as a quarterwave if not better ... with fewer wire needed
dg9bfc sigi
Am 13.07.2024 um 18:18 schrieb Simon:
toggle quoted message
Show quoted text
Hi Sigi
Yes they work well. As long as can get bottom leg clear of gnd. But abit impractical for low bands. Ie 40m high for 80m
Simon
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Re: 2e0ero Magnetic Loop Antenna
Hi Sigi
Yes they work well. As long as can get bottom leg clear of gnd. But abit impractical for low bands. Ie 40m high for 80m
Simon
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Re: Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos
On Sat, Jul 13, 2024 at 03:43 PM, <biastee@...> wrote:
photo of dummy aerial (aerial simulation network) and circuit of dummy aerial.
Hi Chin-Leong, That's interesting, was that the circuit you came up with after our previous discussions about how best to simulate a loop in the absence of a standard method ? I have uploaded my original simple simulator circuit, for others to better understand the context of this discussion. /g/loopantennas/photo/267767/3805080/g/loopantennas/photo/267767/3805081Regards, Martin
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Re: Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos
Recently, I have assembled several LZ1AQ preamps on FR4 1.5mm 2-sided PCB. In the album below, you can find the photos of the assembled preamps, graph of measured and modeled gain, photo of dummy aerial (aerial simulation network) and circuit of dummy aerial. /g/loopantennas/album?id=296366In case the link above doesn't work, look for the album "9W2LC's LZ1AQ amp". I have a problem with the simulation not matching the measurement. So, I am looking for any help / suggestion. This is still a work-in-progress because I haven't measured the P1dB and OIP3. Digression: Not active loop, but I am searching for measurement of the PA0DRT & ON1BES miniwhip for the purpose of validating my simulation. I will be grateful if someone can point to where the data is available. Thanks. 73, Chin-leong Lim, 9W2LC. 9
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W2LC's LZ1AQ amp
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Re: Urban HF Antenna Dilemma: LZ1AQ vs. M0AYF
On Fri, Jul 12, 2024 at 04:18 PM, Raphael Wasserman wrote:
Would you publish as attachments complete s1p files for both amplifier and your loop antenna ?
The list does not allow attachments. Please upload to the Files area, and please include a descriptive folder name and file names. Think about the people who may see these files 2 years from now. ? -- Steve Greenfield AE7HD
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Re: 2e0ero Magnetic Loop Antenna
These are my findings, I must point out I have never cut corners in cost or engineering ( even the vac cap boxes were teflon.) Its just they are not as good as a full size traditional antenna thats well made..ie if a vertical it MUST have a good radial field, if a dipole it MUST be at 1/2wave high etc.
I could not install a massive radialfield on my property so i
searched a different solution ... result is a vertical dipole (so
its "earthless") with endloading on both ends
a longer endloading at the top and a shorter at the base plus off centre feeding lifts the max current spot away from lossy earth and i hope to have fewer "worms-cooking" that way
at least it does not need a mile of wire below it ;-)
details on my qrz.com page
dg9bfc sigi
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Steven Greenfield AE7HD