Date   

Re: Covid..and making phased loop antenna array..

Simon
 

Maybe been abit stupid on the inductance of cardioid loop question.

Impedance i will assume to be resistive for now and 110r..amp input lets say 5r
Hmm matching transformer ..will start with 16:1 and see..



On 16 Jan 2021, at 12:38, Simon via groups.io <ohhellnotagain@...> wrote:

Question for Chris if you dont mind..? May well interest others.

2 actually

playing with endfire loops..2 of side by side facing nw/se

any idea of optimal spacing for 160m?? Or min spacing?

and back to cardioid loops..built another..same issue..just too deaf on 160-40m..using ccw amp plus mine..
so not one to give up!  Is there an optimal resistance for the resistor with varying sizes of loop? ( so i can increase loop dia.) variable resistor to test?
i suspect the “sense” antenna ( wire) i am using is too short..however unless i mount at house gutter height its only ever going to be 1.5-2m long.
also guesstimate of new loop inductance with resistor fitted..this to match ccw etc amp to loop to try to improve operation..I would love to get it working, then try 2 endfire to nw..( with phaser, same length cables etc.)

have had good results with inline loops using delay line..good gain on 40m dropping to poor on 160m though still good back to front..hense why trying to improve with cardioid loops if i can get them to work HERE.

sorry for questions..

ps itching to try out your new preamps.

stay well mag loop simon


Re: Covid..and making phased loop antenna array..

Chris Moulding
 

I'm not sure of the minimum spacing in terms of wavelength for endfire loops. I'll get back to you on that once I've done a bit of study on the subject.

Regarding cardioid loops you could use a variable resistance on the loop but you will probably end up with the same value of 110 ohms as that gives the best front to back ratio.

I initially modeled it in the 4NEC2 antenna modelling program and confirmed it with the prototype.

Using a larger loop would work at 160m  but it will reduce the upper frequency limit of the antenna.

Regards,

Chris


Re: Help making a decision

Tom Crosbie G6PZZ
 

Thanks Chris (and Simon)

Just one other question…

Is a circular loop more efficient an inverse delta?

I only ask because I’ve just worked out a way to hold the wire in a circle (more or less)!

Grateful as ever!

Tom G6PZZ

 

From: CrossCountryWireless@groups.io <CrossCountryWireless@groups.io> On Behalf Of Chris Moulding
Sent: 16 January 2021 13:04
To: CrossCountryWireless@groups.io
Subject: Re: [CrossCountryWireless] Help making a decision

 

Tom,

If you are using the loop antenna inside you will not need the extra gain of the base unit.

The extra gain is really only useful for an inefficient loop or insensitive receivers. I know of one customer who uses one with  a 1930s regenerative receiver with remarkable results!

Regards,

Chris


Re: Help making a decision

Chris Moulding
 

Tom,

If you are using the loop antenna inside you will not need the extra gain of the base unit.

The extra gain is really only useful for an inefficient loop or insensitive receivers. I know of one customer who uses one with  a 1930s regenerative receiver with remarkable results!

Regards,

Chris


Re: Covid..and making phased loop antenna array..

Simon
 

Question for Chris if you dont mind..? May well interest others.

2 actually

playing with endfire loops..2 of side by side facing nw/se

any idea of optimal spacing for 160m?? Or min spacing?

and back to cardioid loops..built another..same issue..just too deaf on 160-40m..using ccw amp plus mine..
so not one to give up!  Is there an optimal resistance for the resistor with varying sizes of loop? ( so i can increase loop dia.) variable resistor to test?
i suspect the “sense” antenna ( wire) i am using is too short..however unless i mount at house gutter height its only ever going to be 1.5-2m long.
also guesstimate of new loop inductance with resistor fitted..this to match ccw etc amp to loop to try to improve operation..I would love to get it working, then try 2 endfire to nw..( with phaser, same length cables etc.)

have had good results with inline loops using delay line..good gain on 40m dropping to poor on 160m though still good back to front..hense why trying to improve with cardioid loops if i can get them to work HERE.

sorry for questions..

ps itching to try out your new preamps.

stay well mag loop simon


Re: Help making a decision

Simon
 

Chris may disagree with this, but buy your good lady a pressie and get it outside..

If inside at a naff location just adding amplification will bring up the noise ( electrical house noise.) just as much as the signals you wish to hear, so you gain nothing.( if not make it worse.) plus risk intermod issues.

Wife bribes work..or just do it and suffer the consequences..lol
I show my wife Mary carlo’s 82m towers when i want to put up antenna’s and show her how lucky she is not to have that!

Mag loop Simon g0zen


Help making a decision

Tom Crosbie G6PZZ
 

Hi Chris,

I hope you can advise re the purchase of an LAA+

My intention is to use this indoors. The loop will be an inverted delta using the supplied wire and will be kept indoors in the first instance until I can smuggle some copper tube past SHWBO.

At that point it will move outside.

I want to take advantage of the additional performance by feeding it from 12V so this suggests the Bias-T. option.

My location seems to be a bit naff so I think it would benefit from the additional amplifier in the Base Unit. However I really don’t want to use a 5V USB supply.

 

I have a very quiet 12V supply that includes a SLA battery and a boatload of 2.1mm DC leads.

Is it possible to have a Base Unit with a 2.1mm DC socket?

 

Struggling to make a decision here….

 

73

 

Tom Crosbie G6PZZ

Nr Chesterfield, Derbyshire UK

Lat: 53.167194 Lon:  -1.399204  Maidenhead Locator IO93HE

RX: Lowe HF250, RSPdx, CCW Sentinel 4, Roberts RM50, Radiomobile TR2, Sony CDX-DAB500U Sangean 808

Ant: 15m MLB wire, MTA Vertical, D707 Active,

 


Re: Covid..and making phased loop antenna array..

Paul Newland
 

"When used in urban or suburban locations customers would probably find little difference when compared with the LAA+ but at a very RF quiet site there would be a significant improvement"
Thank you for the clarification Chris
As most of our neighbours are sheep and although I'm really chuffed with  the LAA+,  used with a RSP to really good effect with my delta loop, this does sound rather tempting.
Best Wishes
Paul



Virus-free. www.avast.com


On Thu, 14 Jan 2021 at 09:59, Chris Moulding <chrism@...> wrote:
Hi Paul,

From customer reports the LAA+ with a metal tube loop is now comparable with a Wellbrook or Bonito loop antenna. It is ideal for probably 95% of customers needing a loop antenna.

There are some customers who need even better antenna performance for radio monitoring or spectral analysis with high end HF receivers at very low noise rural or marine locations.

The aim of the new loop antenna design is to manufacture the best no compromise HF loop amplifier.

Compared to the LAA+ it will have a lower noise floor, better IP3 and IP2 performance and lower RF noise pickup on the ethernet cable used as an RF feeder and power feed.

When used in urban or suburban locations customers would probably find little difference when compared with the LAA+ but at a very RF quiet site there would be a significant improvement.

Regards,

Chris


Re: HF/VHF/UHF Multicoupler

stevebwhite@btinternet.com
 

Chris,
Thank you for such an interesting and informative reply, much appreciated.
regards
Steve


Re: Covid..and making phased loop antenna array..

Chris Moulding
 

Hi Paul,

From customer reports the LAA+ with a metal tube loop is now comparable with a Wellbrook or Bonito loop antenna. It is ideal for probably 95% of customers needing a loop antenna.

There are some customers who need even better antenna performance for radio monitoring or spectral analysis with high end HF receivers at very low noise rural or marine locations.

The aim of the new loop antenna design is to manufacture the best no compromise HF loop amplifier.

Compared to the LAA+ it will have a lower noise floor, better IP3 and IP2 performance and lower RF noise pickup on the ethernet cable used as an RF feeder and power feed.

When used in urban or suburban locations customers would probably find little difference when compared with the LAA+ but at a very RF quiet site there would be a significant improvement.

Regards,

Chris


Re: HF/VHF/UHF Multicoupler

Chris Moulding
 

It depends what you are trying to do.

If you place a wideband pre-amp in front of the Multicoupler then it is likely to overload the receivers connected to it with the high level of RF. At some point you will also overload the amplifier in the Multicoupler.

if you are using it for a specific band of frequencies then you can add a pre-amp and bandpass filter to select a few MHz wide band of frequencies.

As an example I'm tinkering in lockdown with a satellite APRS igate on 145.825 MHz. I'm using a simple 2 element yagi antenna directed straight up to the sky to receive satellite signals. I've built a low noise masthead preamp and filter with an overall gain of 12 dB. This narrowband amplifier doesn't overload the Multicoupler or attached receivers and I'm regularly receiving APRS packets on every pass from the satellite PSAT-1 (NO-84). PSAT-1 only transmits 300 mW and you would normally need a full blown multi-element yagi with azimuth and elevation tracking to receive packets.

So the answer is yes, you can use a pre-amp with a Multicoupler if the gain is below 15 dB and the pre-amp output is filtered.

Regards,

Chris


HF/VHF/UHF Multicoupler

stevebwhite@btinternet.com
 

Hello Everyone,
I am thinking of purchasing a HF/VHF/UHF Multicoupler and wonder if having a pre-amp in line with it would 
be OK?
Thanks


Re: Covid..and making phased loop antenna array..

paul newland
 

On Mon, Jan 4, 2021 at 04:25 PM, Chris Moulding wrote:
At present I'm looking at designing a very high performance loop antenna amplifier. The original Loop Antenna Amplifier was originally meant to be a better low cost alternative to the MLA-30 but due to customer pressure I improved it to become comparable in performance to the Wellbrook and Bonito antenna amplifiers.

With the new design I'm starting from scratch using the best amplifier devices, filtering, weatherproofing and Cat5 interconnecting cable. The first prototype is running with the expected performance improvements. I expect to have the first batch ready in a month or two.







G'day Chris
If you get to see this, what might be the benefits of this new design over the LAA+ used outside?
The LAA+ works very well, but I must assume that there are advantages to be had with the new version, or you probably wouldn't make it.
Best Wishes
Paul


Re: How to make a cardioid loop with a Loop Antenna Amplifier +

Simon
 

Hi Chris and everyone.

hope you are all well?

my initial evaluation of this loop gave me poor results..ie very little signal output..but I am not one to give up.I expect was hoping for a miracle antenna!! ( was only 1m dia single loop.)

After finding the original papers on this it suggests ( but gives no values.) of using inductance and not resistance in the loop ( directly above feed point.)

I ask please for more info..as why 110r used? Does this value need to be altered if loop has higher or lower inductance/ size etc..( i wish to try to use my quad 1m square loop.( total area 4m)

why a resistor and not an inductor?( as per original paper)

I ask as still on a quest to make the best  rx loop array I can here..  ie possibly phasing cardioid loops ( if i can get them to work to my satisfaction..)

My delay line 2 quad loop array is working well, i can get a good f/b ratio, but still struggle to hear USA on 160m ssb.. looking for better!! ( though it trounces the single quad loop!) 

please excuse my questions..all my rf knowledge is home learnt.. (did mechanical and electrical at uni..) so always on a learning curve re rf..( though been 40 yrs now since passed rae!  Getting old...)

regards..stay well Simon g0zen 


Re: New product...HF Antenna Isolator

Simon
 

That should tx well..you may well need a different rx antenna depending upon location and noise..Dont forget if using a fibreglass pole one can make it multiband..( 10-40m) very easily.

Ie a Chris made loop preamp etc..

Sure you have that in hand though..


Re: New product...HF Antenna Isolator

Andy.g4vcn@...
 

Thanks Chris


Re: New product...HF Antenna Isolator

Andy.g4vcn@...
 

Sorry, a quarter wave vertical :o)


Re: New product...HF Antenna Isolator

Andy.g4vcn@...
 

Hi Simon, Well just to test the loop counterpoise out I was going to try 40m,  My garden is too small for a proper radial system but a loop counterpoise would be easily achievable.
Cheers A

 


Re: New product...HF Antenna Isolator

Simon
 

Hi

What vertical you thinking of putting up?
For what bands I wonder?

Simon g0zen


Re: New product...HF Antenna Isolator

Chris Moulding
 

Hi Andy,

The link to a PDF of the article is:

www.crosscountrywireless.net/202010%20loop%20counterpoises.pdf

Regards,

Chris

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