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Re: Optimizing Small Untuned Loop Antennas
Mike, My point was not who likes or dislikes small loop antennas but for any antenna can be calculated or estimated the gain figure or its antenna factor. During my dialog with well respected Martin he was doubtful about the antenna efficiency and antenna mismatch factors to be included in calculation of antenna. So by submitting various articles I showed that is not a concept being Introduced by me but comes from antenna theory that is widely accepted by engineering community. You personally like Chavdar¡¯s parameters used in his work and published in his articles, well he frequently jumps from one subject to other. He introduced common base amplifier with low input impedance for small loop antennas but he did not explained why it was his better choice. Intuitively I feel the same, however, when I review Martin¡¯s plots in his article about Broadband Amplifiers using small loop antennas as well as ?published Duffy¡¯s articles about similar subjects- their choice would be 50 ohm input impedance receivers or even with higher impedances, probably expect frequencies below 1-2 MHz.
Regards,
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On Oct 31, 2022, at 12:37 AM, vbifyz <3ym3ym@...> wrote:
?Rafael,
The article is about a shielded tuned loop with a split capacitor matching to 50 Ohm.
30dB loss on 7MHz compared to a full size dipole is not bad at all for a receive only antenna. Maybe a problem for a quietest of locations - see my comment below on that.
Transmit is a different story, but I am not aware of people using shielded loops and split capacitor matching for TX.
I don't think parameters like loop efficiency and loop mismatch loss are suited to compare small loop RX antennas.
Personally, I like parameters Chavdar LZ1AQ uses in his work on small active loops: the antenna factor (the ratio of the preamp output to the field strength, 1/m units) and the noise floor expressed in field strength units (uV/m). Very intuitive.
Then there is the main reason we use loop antennas for RX - a deep null allowing to minimize some interference (local or DX). In the city and suburbs it improves the signal-to-interference ratio, and allows hearing signals which can not be heard with wire antennas. In quiet rural locations there is no such reason, and there is usually more room available, so small loops are not the optimal solution. If you don't like the poor antenna factor and low efficiency of a small loop, just use a full size wire.
If you are in a quiet but space constrained area, then a short active vertical may be a better solution, because of its higher antenna factor (compared to both wires and loops)? and lower uV/m noise floor (compared to an active loop).
73, Mike AF7KR
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Re: FW: [loopantennas] Optimizing Small Untuned Loop Antennas
Rafael,
The article is about a shielded tuned loop with a split capacitor matching to 50 Ohm.
30dB loss on 7MHz compared to a full size dipole is not bad at all for a receive only antenna. Maybe a problem for a quietest of locations - see my comment below on that.
Transmit is a different story, but I am not aware of people using shielded loops and split capacitor matching for TX.
I don't think parameters like loop efficiency and loop mismatch loss are suited to compare small loop RX antennas.
Personally, I like parameters Chavdar LZ1AQ uses in his work on small active loops: the antenna factor (the ratio of the preamp output to the field strength, 1/m units) and the noise floor expressed in field strength units (uV/m). Very intuitive.
Then there is the main reason we use loop antennas for RX - a deep null allowing to minimize some interference (local or DX). In the city and suburbs it improves the signal-to-interference ratio, and allows hearing signals which can not be heard with wire antennas. In quiet rural locations there is no such reason, and there is usually more room available, so small loops are not the optimal solution. If you don't like the poor antenna factor and low efficiency of a small loop, just use a full size wire.
If you are in a quiet but space constrained area, then a short active vertical may be a better solution, because of its higher antenna factor (compared to both wires and loops)? and lower uV/m noise floor (compared to an active loop).
73, Mike AF7KR
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FW: [loopantennas] Optimizing Small Untuned Loop Antennas
Good evening Martin, ? I found for you a paper published by Duffy at his blog Please read this article especially at its end where he points out about 0.08 % ?efficiency of small loop. Probably now you may understand the meaning of receiving antenna efficiency factor. ? Good luck, ? Raphael ?
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From: [email protected] < [email protected]> On Behalf Of Raphael Wasserman via groups.io Sent: Sunday, October 30, 2022 12:18 PM To: [email protected]Subject: Re: [loopantennas] Optimizing Small Untuned Loop Antennas ? Hi Martin,
1. I was interested to know how works Duffy's published calculator for small loops. Of course, all intermediate steps of calculations with this device were unknown for me but Duffy did mention the reference source
? ? which he used to create a calculation program. I was eager to verify the results using known equitions that are published widely in various technical literature sources.
2. The Gain of antenna is defined through an equation:
? ? ?Ga = 10log 4pi +10log K +10log D + 10log A -20log wavelength of interest, the meaning of? ? parameters you can find in my previous emails.
3.? The efficiency of antenna K is a ratio of radiation resistance to sum of radiation rasistance and ohmic loss of antenna.
? ? ?So, I used R rad= 0.01 ohm and R ohmic resistance=1 ohm, just for a sake of argument for small loop antenna. The K is about 0.01? ( or 1% ), or 10log 0.01= -20 dB
? ? ?Of course, you can use other values to calculate K on your own.
? ? ?In addition, that is true for a? tuned antenna regarding the antenna efficiency factor.
4.? Now regarding any advantage or disadvantage between untuned and tuned small loop antennas using your words - outperforming.
? ? ?Yes, there is an advantage of tuned antenna due to the Q-factor that multiplies accordingly the received signal because
? ? ?Vo=E/AF and Usig=Vo x Q at receiver input when it is a condition of parallel resonance.
? ? ?Many sources say the advantage between tuned and untuned small loop antennas could be expected by 6-10 dB due to the Q-factor.
? ? ?However, we have to take everything in a proper way, considering as well as the presence of ambient noise that will be equally multiplied by the Q-factor ( Unoise ambient x Q ).
? ? ?So, the SNR will not be improved at receiver output unless the ambient noise is significantly less than the thermal noise of your receiver and we can consider only the presence of thermal Johnson noise.
? ? ?Let's take an extreme case when the direction of desired received signal and ambient noise are the same and you cannot minimize with your directional loop antenna...
Regards,
Raphael??
? ? ? ? ? ?
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STLcalc: the missing Linux update message attachments
The attachments on my earlier posts regarding Linux updates were stripped somewhere along the way. So I have placed the attachments for both Linux Mint and Raspberry Pi OS in the following Dropbox location:
These items deal only with the need to mark the STLcalc program file as executable. If you've already done that, there's no need to do anything more.
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FW: [loopantennas] Optimizing Small Untuned Loop Antennas
The mentioned article/file is uploaded as ¡°Antenna_Paper_Part3.pdf¡± ?
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From: [email protected] < [email protected]> On Behalf Of Raphael Wasserman via groups.io Sent: Sunday, October 30, 2022 3:37 PM To: [email protected]Subject: Re: [loopantennas] Optimizing Small Untuned Loop Antennas ? All, ? I am attaching an interesting article where are described factors such as antenna efficiency and antenna mismatch that will effect AF value. This will let you re-think I have not yet introduced any mysterious parameters. ? Regards, ? Raphael ? ? Hi Martin,
1. I was interested to know how works Duffy's published calculator for small loops. Of course, all intermediate steps of calculations with this device were unknown for me but Duffy did mention the reference source
? ? which he used to create a calculation program. I was eager to verify the results using known equitions that are published widely in various technical literature sources.
2. The Gain of antenna is defined through an equation:
? ? ?Ga = 10log 4pi +10log K +10log D + 10log A -20log wavelength of interest, the meaning of? ? parameters you can find in my previous emails.
3.? The efficiency of antenna K is a ratio of radiation resistance to sum of radiation rasistance and ohmic loss of antenna.
? ? ?So, I used R rad= 0.01 ohm and R ohmic resistance=1 ohm, just for a sake of argument for small loop antenna. The K is about 0.01? ( or 1% ), or 10log 0.01= -20 dB
? ? ?Of course, you can use other values to calculate K on your own.
? ? ?In addition, that is true for a? tuned antenna regarding the antenna efficiency factor.
4.? Now regarding any advantage or disadvantage between untuned and tuned small loop antennas using your words - outperforming.
? ? ?Yes, there is an advantage of tuned antenna due to the Q-factor that multiplies accordingly the received signal because
? ? ?Vo=E/AF and Usig=Vo x Q at receiver input when it is a condition of parallel resonance.
? ? ?Many sources say the advantage between tuned and untuned small loop antennas could be expected by 6-10 dB due to the Q-factor.
? ? ?However, we have to take everything in a proper way, considering as well as the presence of ambient noise that will be equally multiplied by the Q-factor ( Unoise ambient x Q ).
? ? ?So, the SNR will not be improved at receiver output unless the ambient noise is significantly less than the thermal noise of your receiver and we can consider only the presence of thermal Johnson noise.
? ? ?Let's take an extreme case when the direction of desired received signal and ambient noise are the same and you cannot minimize with your directional loop antenna...
Regards,
Raphael??
? ? ? ? ? ?
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Raphael Wasserman <wassermanr46@...> added folder /Antenna Mismatch and Effiiciency Factors
The following files and folders have been uploaded to
the Files area of the [email protected] group.
By: Raphael Wasserman <wassermanr46@...>
Description:
Antenna_Paper_Part3
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Re: Optimizing Small Untuned Loop Antennas
All, ? I am attaching an interesting article where are described factors such as antenna efficiency and antenna mismatch that will effect AF value. This will let you re-think I have not yet introduced any mysterious parameters. ? Regards, ? Raphael ?
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From: [email protected] < [email protected]> On Behalf Of Raphael Wasserman via groups.io Sent: Sunday, October 30, 2022 12:18 PM To: [email protected]Subject: Re: [loopantennas] Optimizing Small Untuned Loop Antennas ? Hi Martin,
1. I was interested to know how works Duffy's published calculator for small loops. Of course, all intermediate steps of calculations with this device were unknown for me but Duffy did mention the reference source
? ? which he used to create a calculation program. I was eager to verify the results using known equitions that are published widely in various technical literature sources.
2. The Gain of antenna is defined through an equation:
? ? ?Ga = 10log 4pi +10log K +10log D + 10log A -20log wavelength of interest, the meaning of? ? parameters you can find in my previous emails.
3.? The efficiency of antenna K is a ratio of radiation resistance to sum of radiation rasistance and ohmic loss of antenna.
? ? ?So, I used R rad= 0.01 ohm and R ohmic resistance=1 ohm, just for a sake of argument for small loop antenna. The K is about 0.01? ( or 1% ), or 10log 0.01= -20 dB
? ? ?Of course, you can use other values to calculate K on your own.
? ? ?In addition, that is true for a? tuned antenna regarding the antenna efficiency factor.
4.? Now regarding any advantage or disadvantage between untuned and tuned small loop antennas using your words - outperforming.
? ? ?Yes, there is an advantage of tuned antenna due to the Q-factor that multiplies accordingly the received signal because
? ? ?Vo=E/AF and Usig=Vo x Q at receiver input when it is a condition of parallel resonance.
? ? ?Many sources say the advantage between tuned and untuned small loop antennas could be expected by 6-10 dB due to the Q-factor.
? ? ?However, we have to take everything in a proper way, considering as well as the presence of ambient noise that will be equally multiplied by the Q-factor ( Unoise ambient x Q ).
? ? ?So, the SNR will not be improved at receiver output unless the ambient noise is significantly less than the thermal noise of your receiver and we can consider only the presence of thermal Johnson noise.
? ? ?Let's take an extreme case when the direction of desired received signal and ambient noise are the same and you cannot minimize with your directional loop antenna...
Regards,
Raphael??
? ? ? ? ? ?
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Raspberry Pi OS Linux update for STLcalc
The STLcalc program file needs to have permissions set to executable mode, a fact which I failed to note in the README file. I have edited the README file (attached) to add a step that describes this action. The Dropbox has been updated. For anyone who has already done a download, no need to do it all again. The edited README_V2_RPi.txt file is attached.
If you are a command-line oriented user, open a Terminal emulator and use a chmod +x or chmod 755 command to set the STLcalc file permissions to executable by all users.
Doing the mode adjustment instead via the visual route, right-click the program icon, select the Permissions tab, and set the Execute: entry to Anyone, and click OK.
PS: If this topic is a mystery to you, either ignore it, or visit to find out what I'm talking about.
73,
Gus
KB0YH
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Linux Mint file update for STLcalc
The STLcalc program file needs to have permissions set to executable mode, a fact which I failed to note in the README file. I have edited the README file (attached) to add a step that describes this action. The Dropbox has been updated. For anyone who has already done a download, no need to do it all again. The edited README_V2_Mint.txt file is attached.
If you are a command-line oriented user, open a Terminal emulator and use a chmod +x or chmod 755 command to set the STLcalc file permissions to executable by all users
Doing the mode adjustment instead via the visual route, right-click the program icon, select the Permissions tab, and mark the Program: "Allow ..." checkbox (to effectively do a chmod +x operation). NOTE: This works on Mint v2.3, but may not be an available method in earlier versions of Mint.
PS: If this topic is a mystery to you, either ignore it, or visit to find out what I'm talking about.
73,
Gus
KB0YH
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Re: Optimizing Small Untuned Loop Antennas
Hi Martin,
1. I was interested to know how works Duffy's published calculator for small loops. Of course, all intermediate steps of calculations with this device were unknown for me but Duffy did mention the reference source
? ? which he used to create a calculation program. I was eager to verify the results using known equitions that are published widely in various technical literature sources.
2. The Gain of antenna is defined through an equation:
? ? ?Ga = 10log 4pi +10log K +10log D + 10log A -20log wavelength of interest, the meaning of? ? parameters you can find in my previous emails.
3.? The efficiency of antenna K is a ratio of radiation resistance to sum of radiation rasistance and ohmic loss of antenna.
? ? ?So, I used R rad= 0.01 ohm and R ohmic resistance=1 ohm, just for a sake of argument for small loop antenna. The K is about 0.01? ( or 1% ), or 10log 0.01= -20 dB
? ? ?Of course, you can use other values to calculate K on your own.
? ? ?In addition, that is true for a? tuned antenna regarding the antenna efficiency factor.
4.? Now regarding any advantage or disadvantage between untuned and tuned small loop antennas using your words - outperforming.
? ? ?Yes, there is an advantage of tuned antenna due to the Q-factor that multiplies accordingly the received signal because
? ? ?Vo=E/AF and Usig=Vo x Q at receiver input when it is a condition of parallel resonance.
? ? ?Many sources say the advantage between tuned and untuned small loop antennas could be expected by 6-10 dB due to the Q-factor.
? ? ?However, we have to take everything in a proper way, considering as well as the presence of ambient noise that will be equally multiplied by the Q-factor ( Unoise ambient x Q ).
? ? ?So, the SNR will not be improved at receiver output unless the ambient noise is significantly less than the thermal noise of your receiver and we can consider only the presence of thermal Johnson noise.
? ? ?Let's take an extreme case when the direction of desired received signal and ambient noise are the same and you cannot minimize with your directional loop antenna...
Regards,
Raphael??
? ? ? ? ? ?
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Re: Optimizing Small Untuned Loop Antennas
On Sat, Oct 29, 2022 at 07:47 PM, Raphael Wasserman wrote:
Also I got to the bottom of question about 20 dB difference between the results using Duffy's calculator vs. AF equation. The effieciency of small untuned loop antennas is around 1%, thus creating a 20 dB difference in the calculated results.?
But in a later post you say:- The efficiency will be the same for tuned or untuned small loop antennas because neither radiation resistance nor loops ohmic loss can be changed These seem to be conflicting statements, and I'm getting very confused about your definition of efficiency, which seems to be based on a specific theoretical definition. This may simply be a language issue, but I'm struggling to follow all of the discussion points. In the 'real world', if you consider RF power in vs radiated power (or RX signal in) a tuned loop is demonstrably more efficient than an un-tuned broadband loop. In the case of RX only, once an antenna has sufficient gain (or sensitivity) to be limited by the local noise floor, then it is not possible to improve the received signal to noise ratio, other than by changing the directivity (gain in specific direction(s)) of the antenna. However for small broadband loop antennas, most do not have sufficient gain to be performance limited by the local noise floor (unless you are in an extremely noisy environment), and passive tuned narrow band loops (with a decent Q factor) will generally out perform broadband active loops of similar size, but only over a relatively narrow frequency range. Regards, Martin
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Re: Optimizing Small Untuned Loop Antennas
Rick,
1. The efficiency of antenna K is defined as a ratio of (R radiation/ R radiation + R antenna loss), where R radiation value is significantly less than R antenna loss regardless tuned or untuned antenna. The efficiency of antenna effects G - antenna gain and subsequently AF- antenna factor or he -effective height of antenna.
2. Next factor is to consider when you have a tuned loop antenna, the signal and ambient noise will be equally multiplied by Q -factor of the tuned antenna circuit.
So, there is no win situation either when you deal with tuned or untuned antenna ( signal-to-noise ratio ) unless your antenna is located in a quiet rural area. You probably observed S/N degradation plots presented by Owen Duffy and Co. for different small loop antennae as well.
3. However, in parallel resonant configuration of tuned loop the rejection of unwanted signals and external noise is equally good above and below resonance frequency ( slope of 20 dB/decade).
It may protect your preamplifier from an overload of unwanted signals or noises.
Raphael
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Richard \(Rick\) Karlquist \(N6RK\) Sent: Saturday, October 29, 2022 9:54 PM To: [email protected]Subject: Re: [loopantennas] Optimizing Small Untuned Loop Antennas What can be proven is that the inductive reactance is cancelled out in the case of the tuned loop, but not the untuned loop. I'm not sure what definition of "efficiency" you are using, but a tuned loop will put out a lot more signal into the receiver than the same loop without the tuning. That's the bottom line. Rick N6RK On 10/29/2022 3:59 PM, Raphael Wasserman wrote: Rick,
The efficiency will be the same for tuned or untuned small loop antennas because neither radiation resistance nor loops ohmic loss can be changed...unless you can prove otherwise.
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of
Richard \(Rick\) Karlquist \(N6RK\)
Sent: Saturday, October 29, 2022 6:21 PM
To: [email protected]
Subject: Re: [loopantennas] Optimizing Small Untuned Loop Antennas
On 10/29/2022 12:47 PM, Raphael Wasserman wrote:
results using Duffy's calculator vs. AF equation. The effieciency of
small untuned loop antennas is around 1%, thus creating a 20 dB
difference in the calculated results.
_._,_._,_ You would be doing well to get 1% efficiency with a TUNED loop.
For a small UNtuned loop it would be more like 0.1% efficiency or less.
Rick N6RK
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Re: Optimizing Small Untuned Loop Antennas
What can be proven is that the inductive reactance is cancelled out in the case of the tuned loop, but not the untuned loop. I'm not sure
what definition of "efficiency" you are using, but a tuned loop
will put out a lot more signal into the receiver than the same
loop without the tuning. That's the bottom line.
Rick N6RK
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On 10/29/2022 3:59 PM, Raphael Wasserman wrote: Rick,
The efficiency will be the same for tuned or untuned small loop antennas because neither radiation resistance nor loops ohmic loss can be changed...unless you can prove otherwise.
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Richard \(Rick\) Karlquist \(N6RK\)
Sent: Saturday, October 29, 2022 6:21 PM
To: [email protected]
Subject: Re: [loopantennas] Optimizing Small Untuned Loop Antennas
On 10/29/2022 12:47 PM, Raphael Wasserman wrote:
results using Duffy's calculator vs. AF equation. The effieciency of
small untuned loop antennas is around 1%, thus creating a 20 dB
difference in the calculated results.
_._,_._,_ You would be doing well to get 1% efficiency with a TUNED loop.
For a small UNtuned loop it would be more like 0.1% efficiency or less.
Rick N6RK
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Re: Optimizing Small Untuned Loop Antennas
Rick,
The efficiency will be the same for tuned or untuned small loop antennas because neither radiation resistance nor loops ohmic loss can be changed...unless you can prove otherwise.
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Richard \(Rick\) Karlquist \(N6RK\) Sent: Saturday, October 29, 2022 6:21 PM To: [email protected]Subject: Re: [loopantennas] Optimizing Small Untuned Loop Antennas On 10/29/2022 12:47 PM, Raphael Wasserman wrote: results using Duffy's calculator vs. AF equation. The effieciency of
small untuned loop antennas is around 1%, thus creating a 20 dB
difference in the calculated results.
_._,_._,_ You would be doing well to get 1% efficiency with a TUNED loop. For a small UNtuned loop it would be more like 0.1% efficiency or less. Rick N6RK
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Re: Optimizing Small Untuned Loop Antennas
On 10/29/2022 12:47 PM, Raphael Wasserman wrote: results using Duffy's calculator vs. AF equation. The effieciency of small untuned loop antennas is around 1%, thus creating a 20 dB difference in the calculated results.
_._,_._,_ You would be doing well to get 1% efficiency with a TUNED loop. For a small UNtuned loop it would be more like 0.1% efficiency or less. Rick N6RK
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Re: Optimizing Small Untuned Loop Antennas
All,
Since I have Kraus's book "Antennas for all applications" as my technical bible, I re-read the chapter 6 about loop antennas. He does not use at all in the terminology AF but effective antenna height "he", where he=V/E.
Antenna factor is reciprocal of effective length (height ) of antenna ( AF=E/V ).
Also I got to the bottom of question about 20 dB difference between the results using Duffy's calculator vs. AF equation. The effieciency of small untuned loop antennas is around 1%, thus creating a 20 dB difference in the calculated results.?
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Re: Optimizing Small Untuned Loop Antennas
Hi Martin,
I reviewed recent Duffy's comments in the mentioned blog.
Duffy states: AF db/m= E dBV/m - V dBv,? defining the antenna factor. It is taking without any argument regarding it.
For some reason he did not want to rewrite there AF formula in such way to show all variables that effect the antenna factor. So I will do it once more:
AFdB= 19.8 - GdB - 20 log wavelength, where G - antenna gain can be in addition defined? as
?
G dB= 10 log (4pi x k x D x A/ wavelength ^2 ), where k - antenna effeciency equal to R radiation/ ( Radiation + R loss ), D - antenna directivity and A - antenna aperture.
Note - this AF equation is for 50 ohms antenna load.
What is interesting, when I use Duffy's published calculator in order to calculate small loop antenna factor published in his ealier blog
Duffy references his work to Kraus J etc, "Antennas For All Applications" by Mc Graw Hill, New York.
I should page this book through finding any pertaining? details...
I tied to use? Duffy's calculator? with following parameters: f = 1MHz, loop type=circle, wire diameter=1 mm, loop perimeter=3.14 m, directivity=1.5, load resistance=50 ohm, other loss=0 dB
Duffy's calculator gives me the following results: antenna factor = 36.83 dB/m and antenna gain = - 66.6 dBi
However, when I use above shown equation with the antenna gain of? G= -66.6 dBi value I am getting a different result? of? AF= 56.86 dB/m.?
Why the difference in AF values is so great 20 dB ? I guess, probably he includes the antenna radiation effeciency that is not great for this class of antennas - small loop antennas
Regards,
Raphael
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Re: Optimizing Small Untuned Loop Antennas
A recent comment on Owen Duffy's blog regarding AF.
Regards,
Martin
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Re: New to group and quest for loop¡ #160
Hi Jeff
For 160m? I suggest you think about the on the top band hams reflector.? The way WB5WPA did it allows you to make a quick test on a fixed frequency without a lot of cost and if you have trees it can be a fairly stealthy antenna as well.? If you like it, change to a motorized cap to make it frequency agile.? I've built a couple of these for 80 and 160 and though my contesting skills are poor (detest contests) have had good results with QRP on 160m so that says something about the antenna's efficiency.? The main idea is that very small antennas like the classic 'magloop' because they enclose such a small space, the radiation resistance is in miliohms and that means to get any decent efficiency you would like to keep loss resistance about 10 times less, which is why magloops need big conductors, wide straps connecting to the tuning cap and also a cap with no sliding connection ie you need a split stator or VVC.? This all applies to loops that are defined as small being 1/10th or so of a wavelength in circumference. On the other hand the ARRL antenna book says the smallest "regular" loop antenna is 1/2 wave in length.? This loop I am suggesting is ~1/4 to ~5/16 wave long and has some really neat advantages.? As it encloses a larger volume of space the radiation resistance comes way up and you no longer have to keep loss in the low milliohms to get any efficiency.? This means you can use regular wire for the conductor.? A regular low cost capacitor with sliding contact will also be ok for the same reason.?
The details are in the link so I don't need to repeat it all here but a few guidelines are worth mentioning;? there will be interaction between the bottom wire of the rectangle and earth, and earth losses get reflected into the impedance you will be matching to, so you want the bottom of the antenna a good 2m above the ground or more if possible.? That also makes it good for not clotheslining yourself when you are walking around the yard looking at the person next door washing her car. :)? Another rule of thumb is the longer the wire the higher the impedance for matching.? So this means you can tweak the antenna's match by either changing the wire length or simply adjusting its height above ground.? I find this last to be very handy for portable 160m operation (yes!) where ground characteristics will be different in different locations.? Some collapsible fiberglass poles allow you to support the wires and adjust the height easily.? Also for consideration:? You can certainly build a classic magloop for 160m but if you build it well with low loss it will end up being rather heavy and still fairly large even with two turns and your neighbours will certainly notice it.? It won't be cheap!? It will only be useful for 160m after all that.? On the other hand, activity on 160m tends to be rather sparse and winter oriented with the majority of it going on in the Stew Perry contest weekends.? With this antenna you can put it up all by yourself in about 20 minutes and take it down even faster and afterwards have a couple of 12m poles you can use for other antennas like a nice 40m half square at other times of the year etc. or, use another wire and move the poles closer to get on 80m with it.? I really love this antenna and use my VE2AO magloop tuner for keeping it tracking my VFO.? Had one up the whole winter a couple of years ago and it was very reliable and consistent in use.
Best regards...Joe
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Re: New to group and quest for loop¡ #160
Hello Jeff. A small transmitting loop (STL), or mag loop for 160m is possible, but some compromises must be accepted. I built a three-turn STL for 80-160m use about 12 years ago and have had good experience using it, mostly for SSB round-table use on 75m, and CW on 160m for contesting and DXing.? Programs like LoopCalc and 66pacific (on line) provide some design help, but produce questionable results (because of incorrect inductance calculations and other errors).
Rather than complain about problems, I created the STLcalc program to use correct, validated formulas, and to provide better ease of use where possible. You can get details by visiting my QRZ page (https://www.qrz.com/db/KB0YH). Scroll down to the coverage of loop antennas for pictures and program details.
73,
Gus Hansen
KB0YH
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Augie "Gus" Hansen
VE7VXO