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eHam Forums => SWL (Shortwave Listening) => Topic started by: AUSSIE on January 04, 2014, 03:33:19 PM



Title: Pa0rdt Mini-Whip Active Antenna
Post by: AUSSIE on January 04, 2014, 03:33:19 PM
Hi everyone this is a Youtube Video of my new mini active whip have to say when i received it few weeks ago i thought its going stright in the bin to my surprise its only 10 centimetres in length started at 1.5 metres high picked up a few ndb stations & ameturs talking on 20/40 metres at the moment its 4 metres high picked up lots of aero traffic & volmet stations with in the next few weeks will be around 8 metres high and its giving my 3 wellbrook active loops a good run..

http://www.youtube.com/watch?feature=player_detailpage&v=v7msfFVQCKU

Regards Lino..



Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: W4OP on January 05, 2014, 07:13:06 AM
Until just recently, VK1OD had an in depth analysis of the PA0RDT antenna on his site showing that  the outside of the feed coax is the main antenna. If you write Owen, he would  probably send you a copy if interested.


Dale W4OP


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: AUSSIE on January 05, 2014, 08:21:53 AM
Hi Dale thanks for that im not an expert when it comes to specs and the technically of antennas been in the hobby for 36 years and have been surprised what works and what doesnt when it comes to antennas over the years as one said in another review it was picking same as his wellbrook loop and better some times and im finding that out at a qurter of the price..

Regards Lino..


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: JAHAM2BE on January 06, 2014, 06:00:24 PM
You can still see some of VK1OD's comments on the PA0RDT antenna here:

http://groups.yahoo.com/neo/groups/600m/conversations/topics/8070
http://www.youtube.com/watch?v=EWqJHTOijdE

I've built one of these from scratch. I used it in a second-floor apartment situation where it was impossible to ground the antenna properly. My experience, using it for HF listening, was that the antenna had a lot of noise caused by common mode currents. I understand that these common mode currents are all but impossible to stop if you don't ground the antenna; in particular, choking the feedline without proper grounding is insufficient because the choke impedance will always be less than the extremely high input impedance of the amplifier (which is necessary because the small whip is a high impedance antenna). See these links for some more details:

http://active-antenna.eu/tech-docs/comm-filter-ftp-10.pdf
http://www.qth.net/pipermail/lowfer/2003-September/010196.html

I gave up on the active whip antenna and instead used an active loop antenna (which, unlike the whip antenna, has a very low input impedance, making it easier to choke off common mode currents), the M0AYF active loop design based on 2 BJTs in a differential amplifier arrangement. It works surprisingly well, even inside of a concrete building.


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: W4OP on January 07, 2014, 09:03:50 AM
I have gone  the same route. 7' active shielded loop similar to the Pixel or Wellbrook.
Excellent, balanced deep nulls indicate that the antenna is performing as it should with little common mode issues.

Dale W4OP


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: KD7RDZI2 on February 05, 2014, 04:13:44 PM
Dale, have you ever thought to an Active HF Omniangle with a well matched high IP3 amplifier?


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: ZENKI on April 11, 2014, 07:27:05 PM
You might also read  further information here, especially if you do want to build a better antenna.

http://g8jnj.webs.com/activeantennas.htm

There is a few options there that you could explore.

I would rather build the LZ1AQ antenna.
http://active-antenna.eu/order-and-pricing.php


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: K5TED on May 22, 2014, 06:17:14 PM
So, Aussie, the consensus here is apparently that your antenna can't possibly be working as well as as you claim, despite your favorable comparison, in your particular location, in your particular implementation.

Sheesh... ::)


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: AUSSIE on May 23, 2014, 04:40:54 AM
Hi The antenna is working excellent and bought another oner few weeks ago..

Regards Lino..


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: PBPP on May 24, 2014, 01:34:14 PM
Hi The antenna is working excellent and bought another oner few weeks ago..

Regards Lino..
Yeah right............  I'd bet a 10 foot piece of wire would work much better.
How much are you selling these whiz-bang POS antennas for??

~ Mitch ~


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: KD8IIC on May 27, 2014, 12:01:32 AM
   Why be so Rude P? I have a couple these and they work FB...best to get them above 20 feet I have found....excellent antennas.


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: KD7RDZI2 on May 27, 2014, 10:24:16 AM
There' something I cannot get. The input impedance of the amplifier is extremely high and that's fine as many active antenna are made in this way and the amplifier matches the high impedance of the antenna and the cable. But just close to the antenna you could make a good choke as the impedance on the cable is low if this is desired. The internal unit should just supply the dc voltage so, am I wrong?


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: PBPP on May 27, 2014, 12:29:49 PM
KD8IIC,

Not being rude... just expressing my opinion.  I highly doubt these are anything close to an 'excellent' antenna.   ::)
Strange that you and 'Aussie' both have two of these.  Enough to make a reasonable person suspicious.
So, would you care to qualify your statement with some empirical data??  Preferably something we can all verify??   

Thanks,
~ Mitch ~


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: K0OD on May 27, 2014, 01:45:11 PM
Quote
Yeah right............  I'd bet a 10 foot piece of wire would work much better

:) Quite possibly, PBPP. I use essentially the equivalent to DX longwave... my ham 43' vertical... a VERY short "piece of wire" at 100 kHz.  Works fine and cost me nothing for that VLF capability. I can't believe the garbage SWLs waste money on, and then rave about on EHam.

Did anyone read the article in May's QST (p.93) about Gotham antennas, where-- 50 years later-- the ARRL tells how those products were junk. Gee thanks, League!

Gotham's ads were short on technical details (the average buyer was probably age 14) and long on examples of DX supposedly worked.  That no radial "all band" vertical consisted of an aluminum tube, a coil and an alligator clip.
 


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: KD8IIC on May 28, 2014, 03:46:49 AM
 Considering the fact that some of us do not have the room for a 43ft vertical or any wire antennas then a logical solution is found in obtaining the best working small antenna for the frequencies interested in. If you are looking to get stellar results above 75m, then the PA0RDT is not for you, neither are my two Pixel loops. The frequencies these active antennas seem work best are lower than 7mhz from my experience. LW and BCB reception is vastly improved using a well designed active antenna, for me at least. If you do not want to listen for NDB's or Broadcast stations quietly then these antennas are likely to be a foolish investment of your money...


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: PBPP on May 28, 2014, 06:56:00 AM
KD8IIC,

I'm sure you've got room for a 10 foot antenna and probably longer, right? 

Just so you know, a random wire antenna with a LC tuner will vastly outperform
the four overpriced active antennas, the virtues of which you are extolling. 
Since you haven't provided us with any verifiable data, one can only conclude
your claims are without merit. 

Sorry, but buying any of these active antennas is foolish waste of money,
no matter what type of abode you live in.

~ Mitch ~ 


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: K0OD on May 28, 2014, 09:34:21 AM
Quote
Considering the fact that some of us do not have the room for a 43ft vertical or any wire antennas

I sometimes DX the AM BCB with my ancient Panasonic RF2200 on my BASEMENT workbench. No outside antenna at all. I presume everyone has room for the 8" ferrite rod on top of the 2200.

Heck, one of my wristwatches sets itself using 60 kHz time signals from WWVB in Colorado 800 miles west of me.  The antenna (I Guess there is one) couldn't be more than the watchcase.

On lower frequencies where atmospheric noise is the limiting factor, sometimes a costly antenna helps, but often much less performs just as well. Start with some random hookup wire dangling out a window.
 


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: KD7RDZI2 on May 28, 2014, 11:15:24 AM
KD8IIC,

I'm sure you've got room for a 10 foot antenna and probably longer, right? 

Just so you know, a random wire antenna with a LC tuner will vastly outperform
the four overpriced active antennas, the virtues of which you are extolling. 
Since you haven't provided us with any verifiable data, one can only conclude
your claims are without merit. 

Sorry, but buying any of these active antennas is foolish waste of money,
no matter what type of abode you live in.

~ Mitch ~ 


Well, I don't know anything about the Pa0rdt Mini-Whip, but active antennas ARE NOT a foolish waste of money. If you are interested in SWL try the efficiency of a long wire antenna on the LF. How long should be the wire to get the same efficiency of an active antenna? More, active antennas, excluding active loops, are omnidirectional usually vertically nearly isotropic polarized. A random wire has a distorted pattern and is deeply influenced by both the lengh and the height of the wire and the ground. I am not saying active antennas are better, they are different. Some cost a lot, maybe they are overpriced for what they are, but they can be put close to the ground, you don't need a tower and you save time and sometimes money to install it. Yes they amplify noise too but noise figures are very low often below the atmospheric noise and the amplifier serves more for matching than for amplifying the signal itself. And you don't need a tuner, it's wideband, no switches ... just very convenient.

If you say  that using a simple wire saves you a lot of money I would not be so sure: you cannot leave the wire on the ground: add the costs of a mast, and the tuner, better external, that's also is a lot of money! and still you won't have the LF, the pattern can be distorted on the HF, and you need to tune everytime you move the VFO...


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: G8JNJ on June 10, 2014, 04:02:42 AM
Hi All,

Active antennas are a perfectly valid concept and are frequently used by the military and other agencies.

As long as the intermod performance is adequate for the intended purpose and the noise figure is low enough to be masked by the external noise floor, they can work surprisingly well, particularly on the LF and VLF bands.

If you want to see how well a Pa0rdt Mini-Whip can work when installed properly, try using the University of Twente WEB SDR

http://websdr.ewi.utwente.nl:8901/

This uses a Pa0rdt Mini-Whip with an active receiving element of about 5 by 10 cm. Such an antenna only works well with a good grounding. This one is on top of a 20m high building, the upper part of which is all metal.

A summary of various Active antennas can be found at

http://g8jnj.webs.com/activeantennas.htm

My own design, mounted on a 3m high metal mast, works at least as well on RX as a 10m high vertical and buried radial system. On the LF bands, where the ambient noise level is the determining factor, the active antenna is probably better in terms of RX S/N ratio.

A random wire and tuner is OK if you wish to stay on one frequency, but if you do a lot of tuning around, or want to monitor propagation beacons or similar, it's not really viable to keep on having to re-tune every time you change frequency.

Regards,

Martin - G8JNJ

www.g8jnj.webs.com



Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: KD8IIC on June 10, 2014, 05:59:16 AM
 Hi Martin ; Great info on the web pages. Now we just have to wait and see what the real "Experts" who have unashamedly chimed in to correct us Neanderthals in this thread have to say to correct you on..
I must be a real dolt, my ten feet of wire using a simple LC tuner doesn't work half as well as claimed, maybe it's because I'm using insulated wire and not bare, hi.


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: PBPP on June 12, 2014, 11:49:50 PM
The links Martin gave show no real information on the Pa0rdt antenna, only a similar circuit.

Still waiting for KD8IIC to provide us with some verifiable data on just how well this whizbang active antenna works. 
So...... how about it there Lane?? Care to educate the experts? 

~ Mitch ~


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: G8JNJ on June 13, 2014, 09:24:58 AM
http://dl1dbc.net/SAQ/Mwhip/Article_pa0rdt-Mini-Whip_English.pdf

http://dl1dbc.net/SAQ/Mwhip/pa0rdt-Mini-Whip.pdf

Plus others referenced from my active antennas webpage

http://g8jnj.webs.com/activeantennas.htm

Regards,

Martin - G8JNJ

www.g8jnj.net






Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: KD7RDZI2 on June 13, 2014, 10:51:48 AM
The links Martin gave show no real information on the Pa0rdt antenna, only a similar circuit.

Still waiting for KD8IIC to provide us with some verifiable data on just how well this whizbang active antenna works. 
So...... how about it there Lane?? Care to educate the experts? 

~ Mitch ~

I remember a nice chapter on  active antennas on WRTH 1988. There some of the best active antennas of that time were discussed vs longwires (with high impedance ununs), dipoles and other antennas. Not rocket science but from the practical point of view quite a honest and objective picture of antennas of that era. Strangely enough at that time the best  active antenna were offering quite a higher IP3 than most of the active antennas you find today such as the Pa0rdt. I think the relatively high price for the active antennas you find today might be due to a lack of competition.



Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: PA0DGL on June 17, 2014, 10:56:29 AM
The performance of active antennas like the mini whip can be verified rather well with modeling. But before I did that, it was already noticed that there were serious issues:
1. the J310 has relatively high Cdg and Cgs. In a good design, the influence of the first would have to be minimized by bootstrapping whereas the influence of the second can be made small by taking care of a near 1 gate - source voltage gain. Simulation shows a 2.5 dB loss instead so the effective Cgs is rather high.
2. An emitter follower has a very low output impedance and should be connected to the coax via a resistor of the proper value. That also will half the (already <1) gain.
3. For the relatively high input capacitance, the sensor / whip must be much larger.

So my 10 meter vertical wire in a tree, with 9:1 impedance transformer and proper ground worked much better than any active antenna. That was about 30 years ago. Living in Panama now, lightning storms are a big issue and the hills at my property would require 30 meter or larger towers to erect a horizontal antenna. So I took a second look at active antennas.

A test as in the video that started this thread was changed into a mobile job: portable radio and active antenna on a battery, to discover locations with the lowest RFI where the active monopole can be erected. An active whip with imperfect ground works like an asymmetric dipole IOW no problem. The result was so good (MW stations were heard with good S/N that were inaudible on the ferrite antenna of the Tecsun PL-660) that I designed (and tested) a symmetrical active dipole with, similar results. For the S/N to be comparable to the (now destroyed by a storm) 85 m uphill long wire (slope ~40 degrees) a whip aka dipole half has to be more than half a meter in my designs. No commerce intended - I used to work as designer for a Dutch magazine.

Jan


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: KD8IIC on August 29, 2014, 06:45:48 PM
  Mitch ; You still are a rude person, period. Anyone who puts down someone's favorite item's in this fine hobby and flat out call it a "piece of shit" is quite uncouth... you are a twit.


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: PBPP on September 01, 2014, 12:34:54 AM
Real classy there Lane. 
Since you can't defend the quality or performance of this antenna with real world data, you insult and denigrate me instead. 

Thanks for playing.
~ Mitch ~


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: KD7RDZI2 on December 08, 2014, 02:20:03 PM
Read http://wwwhome.cs.utwente.nl/~ptdeboer/ham/tn/tn07.html

if this is right, the antenna can work well if there is a good ground at the antenna. On the other hand it can work very badly if no ground or bad ground is used.

The concept is interesting, I will try one mobile.


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: KX4OM on December 22, 2014, 07:39:32 PM
Interesting thread. I recently built a voltage probe whip antenna for a 40m homebrew CW receiver for indoor use by my grandson. It's an add-on circuit in the article, "Compact SSB Receiver" in the November 1983 Ham Radio magazine by Rick Littlefield, K1BQT. Rick built his, including the whip, into the cabinet of the receiver. Ours is in an aluminum box on the table beside the receiver. It works, but I have to do some more investigations. The receiver is based on K1SWL's SW-40+, which works fine when we can use an outdoor dipole. The receiver is on my web site.

Ted
www.kx4om.com


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: PA0DGL on January 12, 2015, 03:01:32 PM
My version of active whip has been working for over 6 months and rather satisfactory. In July 2014 I uploaded early results. SW broadcasting, CB DX (US, Mexico), 20 m SSB ham radio (DX if Belgium classifies for that), mixed. Due to the wet season with inevitable thunderstorms in Panama, at lower frequencies there's a background of noise caused by lightning.
Reception samples: http://singularian.50megs.com/music/Radio%20reception%20samples.mp3


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: KA2QPG on November 19, 2017, 09:44:50 AM
I know this thread is a bit stale, but inquiring minds will end up here if they Google "PA0RDT mini whip".

Rather than contribute to the "noise" from uninformed commenters, I invite one and all to LISTEN to a PA0RDT mini whip on the SDR receiver of KB8SPI near Detroit.  Follow the link from http://sdr.hu/ to get there; Firefox and Chrome work best.  I did, and was very favorably impressed, especially at the low end of the spectrum. I could copy dozens of NDB's with ease, at noon, which is a difficult feat at most locations and with most antennas.  The RX must be in a good, quiet spot, but the active antenna is doing a fine job too.  I have built other short receiving whips ("E-field probes") with similarly good results.  -KA2QPG


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: K0OD on November 20, 2017, 06:57:49 AM
That may only tell you that KB8SPI has a good quiet location for receiving NDBs or that he has lots of beacons nearby  (and he does... Detroit). Or that propagation was good when you listened. Jeesh!  Why do so many of these endorsements for active antennas read like ads? If you've done valid A/B comparisons between two antennas then post those results.

For longwave how about using WSPR on the new 630 or 2200 bands for testing? I can regularly print Hawaii on 474 KHz  with my DXE ham vertical for an antenna. And it didn't cost a cent extra for its longwave capability.

Quote
"Rather than contribute to the "noise" from uninformed commenters..."
 
Glad your first EHam post cleared up everything.



Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: PA0DGL on November 20, 2017, 08:34:33 AM
I visited the suggested page and checked a few transmissions that should have comparable results with my location in Panama. These are 4583, 7646, 10100.8 (German meteo, RTTY), 6358.5, 8439 (Dutch navy, RTTY), 8473 (US CG Miami, 45 RTTY and FEC). Only the last one can be received in daytime here, the others after sunset. SDR here G31DDC, mode FSK (frequences will differ when using SSB mode). The KB8SP setup indeed could receive 8437 but not the others. However the waterfall display suggests a lot of interference from the usual culprits (switch mode power supplies etc.) and the other RTTY signals were below the noise floor. From my perspective that is a bad location for an omnidirectional whip (mini or otherwise). So I visited a few other SDR setups which confirmed that for a whip, location and altitude are everything but increasingly rare. I lost interest in whips a while ago and am doing some design work on low noise loop amps, including the issue of active load resistors (for mini dual flag) that produce less noise than passive resistors.


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: G4AON on November 21, 2017, 04:03:45 AM
I don’t understand the hostility towards active antennas expressed by some on this thread, nobody is under any obligation to use one, buy one, or give up radio because they haven’t got one.

The PA0RDT antenna is one of the simplest to build and install, I’ve added a page to my web site that may help others, on a “take it or leave it” basis.

FWIW, mine is used with a QS1R SDR receiver and CW Skimmer Server to provide my own local “spots” on my logging program. It’s an invaluable tool to me. My version of the DC injection (bias T) drops the active antenna supply when transmitting to avoid overload or damage to my SDR.

73 Dave
http://www.qsl.net/g4aon/


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: VA3VF on November 21, 2017, 05:16:26 PM
I don’t understand the hostility towards active antennas expressed by some on this thread, nobody is under any obligation to use one, buy one, or give up radio because they haven’t got one.

For the cost involved, it simply does not make any sense not to try. It does not compare to a log periodic, but it does work, specially below 16MHz.


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: ZENKI on November 24, 2017, 08:48:36 PM
Its just ignorance. It is a well established fact in EMC and  Professional HF circles that active antennas always will have the  feedline as  part of the antenna. 

There are many active antenna designs that hams have not tried, if they did try them they would not be so negative about  what is possible with active antenna designs. We  as hams tend to use the worst performing of designs like small 1 meter loops and noisy voltage probe antennas with poorly decoupled feedlines..

Hams should try some of the larger active loop antennas ,, something  like the Bonito  MegaActiv loop and see how well these antennas perform.

http://bonito.net/ml052/en/index.html


I don’t understand the hostility towards active antennas expressed by some on this thread, nobody is under any obligation to use one, buy one, or give up radio because they haven’t got one.

The PA0RDT antenna is one of the simplest to build and install, I’ve added a page to my web site that may help others, on a “take it or leave it” basis.

FWIW, mine is used with a QS1R SDR receiver and CW Skimmer Server to provide my own local “spots” on my logging program. It’s an invaluable tool to me. My version of the DC injection (bias T) drops the active antenna supply when transmitting to avoid overload or damage to my SDR.

73 Dave
http://www.qsl.net/g4aon/



Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: K4FMH on November 25, 2017, 12:15:05 PM
Mitch PBPP,

Since you like objective facts, your statements regarding active loop antennas, such as Andy Ikin’s Wellbrook line, are as FOS as a Christmas Turkey. There are MANY technical comparisons and evaluations of them. You could’ve googled them. Much lower noise and nulls that are directional with a rotator than your “tuned” length of wire. The Quantum Loop (and the older Kiwi Loop) achieve very good results on MW and KW where your LW would llikely be a good noise antenna for a phaser.

Now, the pard0t antenna is something I’ve just purchased but have not installed. I’ll put it up about 12’ on a PVC pipe behind an evergreen tree next to my house with the ground being attached to the house electrical ground nearby. I’ll likely do some comparisons against my Wellbrook 1530 and MFJ Rx Loop...and perhaps a “tuned” long wire. I’ll see how it works. But I WON’T dismiss it out of hand without these direct comparisons!

KD8IIC,

I'm sure you've got room for a 10 foot antenna and probably longer, right? 

Just so you know, a random wire antenna with a LC tuner will vastly outperform
the four overpriced active antennas, the virtues of which you are extolling. 
Since you haven't provided us with any verifiable data, one can only conclude
your claims are without merit. 

Sorry, but buying any of these active antennas is foolish waste of money,
no matter what type of abode you live in.

~ Mitch ~ 


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: PA0DGL on November 25, 2017, 06:53:28 PM
Quote
Its just ignorance. It is a well established fact in EMC and  Professional HF circles that active antennas always will have the  feedline as  part of the antenna. 

The probably too obvious prevention of feed line issues is to abandon the use of an active monopole (by whatever (commercial) name) and to use an active dipole instead. That does away with the demand for a good (or any) earth as it also will work in free space. Common mode rejection can be made high by the use of a differential first stage and a second stage coupled to an RF transformer. 


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: KX4OM on December 07, 2017, 09:28:30 AM
Try out a voltage probe antenna, it is free; it uses the internet.

You can check out the activity on 20 meters SSB right now, IV3CVN calling CQ DX on 14.245, heard from the WebSDR at he University of Twente, The Netherlands. That is a voltage probe antenna based on the PA0RDT. The SDR was built(hardware and software) by Pieter, PA3FWM at UTwente over a period of about 8 years, continually improving it. The antenna is mounted on some air conditioning on the roof of the building. I often listen to 40 meters in the early evening to east and midwest US hams working Europe.

http://websdr.ewi.utwente.nl:8901/

Ted, KX4OM  


Title: RE: Pa0rdt Mini-Whip Active Antenna
Post by: W4OP on December 08, 2017, 04:16:47 PM
If one does not believe that the outside of the coxial shield (or a conducting mast) does not play an important part in the short active whip, please see Owen's article. It is only relatively recently that active whip designers have had to admit that the active whip itself does not tell the entire story. Argue  with Owen if you will- I see nothing incorrect in his analysis:
http://owenduffy.net/antenna/PA0RDT-MiniWhip/

With that said, I do use an active whip on a grounded tower- way out in the woods for some LF work, but my Shared Apex Loop Array being electrically steerable outperforms it.

Regards,

Dale W4OP