Antennas By N6LF

Antennas

Even after more than a hundred years of work, antennas remain a rich field for investigation and innovation.   Since I was first licensed over 70 years ago antennas have been my passion.  Amateurs rarely design and build their own equipment these days, but antennas are often home brewed to improve station performance at modest cost.  70 years ago, Tom Erdmann, W7DND(SK), told me that if I had $100, I should spend the first $90 on the antenna, the next $9 for the receiver and the final $1 on the transmitter. Of course, prices have gone up bit, but those proportions are still sound advice. I can honestly say I have a lot more time and effort invested in my antennas than in station equipment.  This web site provides access to my articles and notes, some of them published in ham journals and others more informal.  All of them should be viewed as "work in progress, subject to revision". My work is a mix of analytic (calculations), modeling or lab and field experiments on actual antennas. Each of these has its place but the best picture emerges when all three techniques are combined.

Please note, I try to close each post to comments. Once in a while I forget to push the right button, and a post may be open. However, I assume I'm perfect and always have the posts closed, so I don't look for comments.

Loop RX antennas with deeper broadside nulls

Loop RX antennas can have deep broadside nulls but only when the loop is quite small which means the signal output may be small, perhaps too small at LF or MF.  The broadside response can be suppressed even in large loops in several ways which is the subject of this note: Download 2023 loop pattern study

My ARRL articles

Over the years I've often posted articles I've written for ARRL periodicals but not all of them have been posted and those that have are not all that easy to locate on my very informally arranged site.  Here are all 35 of my current articles:

Download Antenna Compendium V4 1995 Double Extended Zepp

Download Antenna Compendium V5 1996 Broadbanding Half Square

Download Antenna compendium V5 1996 Low-band halfsquare array

Download Antenna compendium V6 1999 Monster Quads

Download Antenna compendium V6 1999 Short radials

Download Com Quarterly 1997 Lazy-H Vertical

Download NCJ Mar-Apr 2003 Single Support Gain Antennas for 80 and 160m

Download NCJ May-Jun 2009 3-Element 160m Vertical Array

Download NCJ Sept-Oct 2000 Gain Antennas for 80 and 160m

Download QEX Jan-Feb 2004 Sloper Arrays

Download QEX Jan-Feb 2009 ground systems part 1

Download QEX Jan-Feb 2009 Ground systems part-2

Download QEX Jan-Feb 2010 Ground systems part 7

Download QEX Jul-Aug 2009 Ground systems part-5

Download QEX Jul-Aug 2015 Rr Part I

Download QEX Jul-Aug 2018 Tree Conductivity

Download QEX Mar-Apr 1999 Another view of verticals

Download QEX Mar-Apr 2009 Ground systems part-3

Download QEX Mar-Apr 2012 Elevated Gnd systems part 1

Download QEX May-Jun 2002 Foil Conductors

Download QEX May-Jun 2009 Ground systems part-4

Download QEX May-Jun 2012 Elevated Gnd Systems part 2

Download QEX May-Jun 2013 short verticals for 160m

Download QEX Nov-Dec 2000 antenna wire conductors

Download QEX Nov-Dec 2006 Soil Parameters at HF

Download QEX Nov-Dec 2009 ground systems part-6

Download QEX Nov-Dec 2016 Soil characteristics using low dipole

Download QEX Sept-Oct 2015 Rr Part II

Download QEX Sept-Oct 2016 2-loop rx antenna

Download QEX Jul-Aug 2016 BOG

Download QST July 1995 Wideband 80m dipole

Download QST July 2000 Vertical Ground systems

Download QST June 2016 BOG

Download QST March 2010 Ground System Experiments

Download QEX Jul-Aug 2024 Rr thoughts

 

Measuring soil electrical characteristics-an update

In the Nov/Dec 2006 issue of QEX I had an article on measuring soil electrical characteristics using probes inserted into the soil.  Since that time there have been a number of developments which make those measurements easier and more accurate so it's time for an update: Download Measuring Soil Electrical Characteristics

Loop on the ground RX antennas

I'm continuously seeking a better LFMF receiving antennas.  I've tried many different kinds but had not tried a simple loop lying on the ground, a LOG.  I had been very skeptical of these but tried one anyway.  The result, at least for me at my QTH, was very successful.  Here is a note showing the details along with WSPR comparisons between antennas over different paths: Download 630m LOG notes.  I'm not suggesting this is an antenna for everyone but as shown in the note it works great for me.

Multi-turn loop receiving antennas for LFMF

For the next edition of the ARRL Antenna Book (the 25th) I've written a section on Multi-Turn Loop Antennas for LFMF reception.  It will be many months before this published and available from the ARRL.  I felt the topic might be of more immediate interest to the LFMF gang and have permission to post a copy of the draft: Download Chap 22 LFMF RX loops .

The ARRL note mentions direct experimental measurements of self resonant frequency.  Here is a note with more detail on the measurements and modeling comparisons between different versions of NEC:  Download Loop excerpt 2

Switchmode converter book

Many years a go Ed Bloom and I wrote a book on switchmode converter circuits.  I have a .pdf of it for anyone interested: Download Modern DC-to-DC Switchmode Power Converter Circuits

Loop RX antennas

Multi-turn loop antennas are popular LF-MF receiving antennas and while there is lots of info on them I've recently turned up a really neat technical paper on "Coil Antennas", circa 1919 which may be of some interest.  Download Coil Antennas 1919

Valley Radio Club talk 7 Feb 2020

Here is the file for the talk I gave last night.  73

Download 2200 and 630m Presentation -4

 

LFMF notes

Here are some notes on LFMF tuning inductors which may be of interest:

Download Optimum Inductor l-D ratios

Download Optimum Q LFMF loading inductors

Download Wet Inductor Tests

630/2200m TX antenna

Download 630-2200m N6LF TX antenna

I've rebuilt my 630m TX antenna and retuned it to 2200m.  630m tuning will be added in due course.  Here is a description of the latest LF/MF TX antenna at N6LF

A note on floating short circuited loops for inductor tuning.

In older equipment (circa WWII) we occasionally see a short circuited loop or small disc inside a coil to adjust the inductance.  This certainly works but has a bad effect on coil Q.  Attached is a very short note on a experimental test of this type of inductance adjustment.  Download Chapter 6 tuning loop note

Snubbers for Electronic Circuits

Some years ago I wrote a book on snubber circuits for power electronics.  Strictly speaking this is not a hot topic for amateurs but I thought it might help a few so here it is: Download Snubber e-book complete .  For those who don't need to know how to build the watch here's a much shorter summary: Download CD snubber design .

I have also had requests for copies of some of my old technical papers, applications notes, etc.  As I scan them I'll add them to this post.  Recently I was asked for Intersil applications note AO35: Download Intersil AO35

New 630 transmitting antenna a WD2XSH/20

I have recently rebuilt my 630m antenna to use a counterpoise in place of the radial system of 128 wires lying on the ground.  I wanted to see if a much simple counterpoise system would provide comparable efficiency.  Take a look at: Download N6LF Transmit Antenna July 2017

630m-2200m talk

I gave a short talk last night to some local hams on our new 630m and 2200m bands.  Here is PowerPoint file for that talk: Download 2200 and 630m Presentation -2   that's a .ppt file.  For new software using the .pptx format: Download 2200 and 630m Presentation -2 . 

LF-MF antenna notes

 

The present draft of these notes, while far from perfect, may be helpful to many amateurs.  For that reason I've posted them in their present form with the understanding they will be revised, probably several times, in the coming years. 

By all means let me know if I've forgotten something useful and, even more importantly, if I've made a mistake!  A lot of other peoples work has been included but the mistakes are all mine!

GL and 73, Rudy N6LF, WD2XSH/20

LF-MF notes: 

Download Preface-Table of contents

Download Appendix 4- ground systems as reflectors

Download Chapter 1

Download Chapter 2

Download Chapter 3

Download Chapter 4

Download Chapter 5

Download Chapter 6