Links to useful resources
Antennas
Cebik Website and Document Collection - Many articles discussing and analyzing antenna designs and ideas.
Antennas for Receiving and Transmitting - W8JI.
Q82.uk Antenna and radio related projects for the home constructor.
Doublets - Horizontal
- Introducing the "All-Band" Doublet - Cebik
- 10 Frequently Ask Questions about the All-Band Doublet - Cebik
- 80-Meter Doublet - KV5R
- G5RV and ZS6BKW
- Doublet Antenna - Me
Doublets - Vertical
- A Vertical Doublet for 30-10 Meters - Cebik
- A Big Vertical Antenna Project - KV5R
- Simple Multi-Band Vertical Dipole - DJ0IP
- 40 ft (12 m) Vertical Doublet - Me
Dipoles - 80m Short
Coil Loaded Dipole for 80 meters - OH7SV, 19 m / 62 ft long.
Short Efficient 80m Antenna - DJ0IP, 14 m / 46 ft long, balanced feeder with custom matching network.
End Fed Half Wave
- The End Fed Half Wave Antenna - AA5TB, theory and single band matching networks
- End Fed Half Wave MultiBand Antennas - WA7ARK
- ARRL End Fed Half Wave Antenna Kit doing it cheaper and better - WA7ARK
- Even more information about End Fed Half Wave Multiband Antennas - WA7ARK
Inverted L
FCP (Folded Counterpoise) - K2AV, info on 160 and 80m Inverted L designs, and folded counterpoises for smaller lots.
Straightening Out the Inverted-L - Cebik.
Mobile (HF)
K0BG - All things HF mobile.
Building and Operating A Mobile HF Station.
Moxon Rectangle
Moxon Rectangles and Online Calculator - Cebik.
Moxon Rectangle Generator - AC6LA, Windows app, also generates EZNEC and NEC model files.
Off Center Fed Dipoles
- Multiband HF Center‑Loaded Off‑Center‑Fed Dipoles - ON4AA
- OCFD Antennas - DJ0IP
- End Connected OCFD - DJ0IP
- Broadband 80/160 Meter Dipole - K5GP
- Multiband Off-Center-Fed Dipoles for 160 & 80 Meters - KC1DSQ and W1IS
- A Better Off Center Fed Dipole? - Me
- Notes of Mr. Windom's "Ethereal Adornments" - Cebik
Phased Arrays
Only works properly when the current magnitudes and phase are correct, easier said than done.
Receive Only
Dedicated receive only antennas become useful below 20m or 14 MHz where noise becomes an increasing problem:
- Noise typically travels as a vertically polarized ground wave.
- Omni directional ground mounted verticals are the worst, the current maximum is at ground level. An elevated vertical can be better.
- Verticals with elevated current maximums are better - e.g. Half Square, Voltage Fed T, vertical doublet etc.
- Horizontal antennas by virtue of being horizontally polarized pickup much less noise.
- Horizontal loops (popular on the lower bands when there's room) are better again from not having any open high impedance ends, and high common mode input impedance.
- Proper current choking at feed-points and ladder line to coax transitions prevents the shield of the coax becoming part of the antenna system reducing noise pickup and potential RFI on transmit.
- Proper station grounding, Grounding and Bonding for the Radio Amateur covers it all.
- Approaches to Tackle Noise Problems Vary, Remedies Elusive - ARRL Letter March 04 2021
- How To Quickly Locate And Fix Power Line Interference.
- QRM Guru.
- I have RFI Series - NK7Z.
RDF (Receiving Directivity Factor)
- Helps determine the performance of antennas on receive.
- RDF is the difference between the peak forward gain and averaged gain in all directions.
- Receiving Basics and The Challenge: Receiving Antennas.
- More about The RDF Metric.
- XLGTa - Antenna Gain/Temp and Other 3D Metics.
There are several types of receive only antennas for the lower bands:
- Beverages are the most popular choice if there's room available.
- Pennant Flag.
- Waller Flag.
- EWE.
- K9AY.
- LoG (Loop on Ground).
- Horizontal loop low noise receiving antenna by K6STI.
- DK6ED DX Loop - Choice between magnetic or electric magnetic loops.
- Active Antenna Amplifier kit for small loops - LZ1AQ, switchable inputs, strong signal limiting (e.g. 1500W from nearby antenna), control, power, and RX signal via one shielded CAT5 cable.
Traps
Some hints/tips on how to assemble nice coax traps - ON7EQ
Modeling Trap Antennas - Cebik
Trap Modeling Tips and Building Coaxial Traps - ON5AU
The Multi Band Trap Antenna - K7MEM
Coaxial Traps for Multiband Antennas - DG1MFT
Building Coaxial Cable Traps - W8WWV
Attic Coaxial-Cable Trap Dipole (10, 15, 20, 30, 40, 80m) - NU3E
Two New Multiband Trap Dipoles (80/40/20/15/10 & 80/40/20/17/12) - W8NX.
Space-Efficient Dipole for 40, 80, and 160m - W8NX.
160 / 80 / 40 m Trapped Dipole - SM2YER.
Verticals
The 43 foot vertical – The answer to everything?
160 and 80 Meter Matching Network for your 43-foot Vertical - AD5X. High power and remote switched matching to enable (more) efficient operation 160m and 80m.
End-Fed Center-Fed 20-Meter Portable Antenna - AD5X.
TC2M (Terminated Coaxial Cage Monopole) - A new design of broadband HF vertical antenna - G8JNJ.
Gain Master - Broadband center fed 5/8.
VHF
Folding Moxon/Yagi hybrid for satellite work
High Performance Quad and Yagi antennas, home of the LFA Yagi - G0KSC
VHF/UHF Low Noise Yagis - DG7YBN
VHF/UHF Optimized Yagi designs -YU7EF
Misc
Automatic Antenna Tuners & Couplers - AB4OJ.
Optimal 80 meter dipole height for NVIS - OH7SV.
At What Height Should I Mount My 10-Meter Antenna? - K9LA.
Bobtails and Half Squares - K3KY.
Collection of Antenna Designs - SP3L.
Stacking Yagi Antennas - G3SEK.
UA9BA Spitfire Collinear Arrays at UA2FW's - go big or go home!
Terminated Coaxial Cage Monopole - A new design of Broadband HF vertical antenna - Martin Ehrenfried (G8JNJ).
Low Band Antennas at W3LPL. Horizontal antennas at 1/2 wavelength height or more. Verticals where this is not possible - typically 160m, sometimes 80 and 40m where a horizontal antennas cant be positioned high enough.
Series of QEX articles on ground system experiments. Quite possibly HF radials demystified. Information from actual experiments and NEC2 models. Key points:
- For ground mounted verticals 30 to 60 radials (more becomes an exercise in diminishing returns) no longer than the vertical element it self.
- Better to have more shorter radials than fewer longer radials.
- Elevated verticals, three resonant (1/4 wavelength) radials is sufficient.
Online Forums
- r/amateurradio subreddit
- Antennas Feedlines Towers & Rotators - QRZ Forums
- Antennas, Towers and more - eHam Forums
- Ham Antennas - Groups.io
Antenna Modeling
Learning how to use modeling software and knowing their limitations can be very useful in learning more about how they work, and evaluating options and ideas to suit a need or goal.
MMANA-GAL - Easier to get started with.
EZNEC - High accuracy ground, virtual transmission lines, loads, wire insulation, supports NEC4 and NEC5 engines, well written manual. Allows the modeling of complete and more complex antennas systems.
AutoEZ - Automation tool for EZNEC, includes an optimizer.
Advanced Antenna Modeling Book - ON5AU, covers EZNEC and AutoEZ beginner to advanced.
4NEC2 - Popular alternative.
Antenna Models - Most people don't make an effort to share antenna models, here I've put a number of mine online, many could be used as a starting point. Mostly EZNEC models.
Baluns
They do two things, transform from one impedance to another, and/or choke common mode currents on unbalanced feed-lines such as coax.
A current choke balun should be used anywhere an unbalanced feed-line (coax) connects to:
- Balanced line - a common configuration with a G5RV (and variants) or horizontal loops.
- Antenna feed-point - isolates the feed-line from the antenna prevents the coax shield from becoming part of the antenna and radiating (RFI) and noise pickup on receive.
The Private Life of Coax Cable - GM3SEK.
Symmetrising Transformation Lines & Baluns (VHF/UHF) - DG7YBN.
Common mode chokes, and follow up in RadCom High Performance Chokes - G3TXQ.
Common mode chokes - ON4AA.
K9YC publications has a number of articles and information on chokes.
Choosing the Correct Balun - W8JI.
More pages about baluns - W8JI.
Baluns: What they do and how they do it - W7EL.
A good post on QRZ about common mode currents - WA7ARK.
Toroidal Ferrite Core Inductor Calculator, and QRZ thread discussing it - SP3L.
In Counterpoise Systems W8JI explains why the coax shield should always be choked, and why a current balun should always be used to force equal and opposite currents into the antenna system, balanced or un-balanced.
Clean Up Your Shack - GM3SEK Mains Filter.
K9YC has some pretty extensive information on chokes among other things. The main document on chokes is A Ham's Guide to RFI, Ferrites, Baluns, and Audio Interfacing, another good document with less fine detail/more to the point is NCDXACoaxChokesPPT.pdf. Links to slide decks on chokes and other information can be found at Audio Systems Group Inc, Publications,
Air core or "ugly baluns" wound out of coax are popular. What's not always commonly conveyed is they're not multi-band, and they ideally need to be measured vs winding one and hoping for the best. G3TXQ has some good information on them at http://www.karinya.net/g3txq/chokes/. An article by VE3VN Air Core Coax Chokes: Good, Bad, and Ugly explains further.
Commercially made baluns can be hit and miss when it comes to quality of materials and construction, often you cant even see what's inside.
From personal experience Balun Designs are the baluns I buy and use - they show pictures of the insides, and you can take the lid off and see inside. They appear to be high quality, and reasonable prices for what you're getting. Consider this when building baluns with out a means to test and verify what you have.
Palomar Engineers is a good source of information and ferrite products.
Power ratings are important, typically the rating quoted is for low SWR. Power levels need to be derated for high SWR use, otherwise the balun will get hot and fail, maybe even catch fire - this happened to at least one person I know.
Feedlines
Phasing & Matching Lines (VHF/UHF) - DG7YBN.
Ladder Line - KV5R.
Coax Loss Calculator - As noted, less accurate than TLDetails - KV5R.
TLDetails - Impedance and reflection coefficient parameters (SWR, reflection coefficient magnitude Rho, or Return Loss RL in dB) at both ends of a transmission line and the details of power loss in the line - AC6LA.
Some (Old) Notes on Home-Brew Parallel Transmission Lines and Handling Parallel Feedlines - Cebik.
Parallel Circular Conductor Transmission Line Calculator - ON4AA.
Using Hardline in a Ham Station - K9YC.