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Understanding high-frequency (HF) skywave propagation is crucial for amateur radio operators seeking to optimize long-distance communications. This resource details the fundamental principles of HF radio propagation, including the properties of electromagnetic waves, the characteristics of various HF bands, and distinct propagation modes such as skywave, ground wave, and line-of-sight. It places significant emphasis on the ionosphere's pivotal role in refracting HF waves, explaining how solar activity directly influences ionospheric conditions and, consequently, propagation paths. The resource integrates real-time monitoring capabilities, featuring dynamic charts and data from DX clusters, WSPRnet, and the Reverse Beacon Network, which allow users to track current band activity and propagation conditions globally. It also delves into advanced topics like Near Vertical Incidence Skywave (NVIS) and gray line propagation, providing insights into ionosonde data and various propagation prediction models. The site presents a detailed analysis of solar-terrestrial interactions, geomagnetic indices, and space weather phenomena, illustrating their direct impact on HF communication reliability. Practical tools and applications are highlighted, including real-time QSO planners, online Maximum Usable Frequency (MUF) maps, and alerts for solar flares or geomagnetic storms. The guide systematically breaks down complex concepts into accessible chapters, offering a structured approach to learning about ionospheric regions, diurnal and seasonal effects, and the interpretation of propagation indicators like foF2, MUF, and Lowest Usable Frequency (LUF). This makes it a robust reference for hams aiming to deepen their technical understanding and improve operational effectiveness.

Built around a 1/2" pvc frame, Larry's 6 meter moxon antenna is made from #8 aluminum ground wire

Thermocouple ammeters are very rare these days, but the job they were perfect for - measuring antenna currents - is still a modern requirement especially in respect to groundplane currents. By David A. Reid PA3HBB G0BZF

A quarter wave vertical end-fed antenna for the 40 meters band. As all vertical antennas, also this aerial requires a good earthing system. In this project the ground is composed by twelve 4, wires buried in the lawn by using a spade to create a slit to drop the wire into.

3 Band vertical Marconi-antenna for the bands 40, 80, 160 meters with a ground net of wires as radials.

The Kenwood TH-F6A handheld transceiver can achieve an extended transmit frequency range of 137-174 MHz, 216-235 MHz, and 410-470 MHz by removing a specific diode and chip resistor from the main PCB. This modification also expands the receive range on the A-band to 142-152 MHz, 216-235 MHz, and 420-450 MHz. For the TH-F7E, the transmit range extends to 137-174 MHz and 410-470 MHz, with a corresponding receive range on the A-band. Performing these hardware changes will reset and initialize the radio's memory contents, necessitating prior backup of important channel frequencies. Instructions are provided for constructing a homemade PC programming cable compatible with the Kenwood TH-G71A, TH-F6A, and TH-F7E. The interface utilizes an RS-232-to-logic (0-3.3V) level-shifter and a full-duplex serial connection, adapting the Kenwood PG-4S cable schematic for the TH-G71's 2.5mm and 3.5mm phono plugs. Specific schematic tweaks include changing R1 from 150 ohms to 1K ohm to optimize power from the serial port and adding a 150K ohm resistor between the Radio TXD and ground to manage the 3.3V I/O pin. Detailed plug pinouts for the 2.5mm and 3.5mm connectors are presented, with the interface's TXD connecting to the ring of the 2.5mm plug and RxD to the shield of the 3.5mm plug. Ground connects to the shield of the 2.5mm plug, while the tips of both plugs are no-connects. Debugging procedures cover verifying positive and negative power rails from the serial port, checking component polarities, and testing level-shifting and inversion functions of the interface. Software setup involves enabling "TC ON" (Menu 15 for TH-G71, Menu 9 for TH-F6) and using Kenwood's MCP programming software.

A 5/8 vertical groundplane antenna for 50 mhz

The Ameritron AL-1200 Amplifier is in current production. In its factory configuration it uses a single 3CX1200A7 (triode) tube, grounded grid configuration. Re-tubing the AL-1200 with a GS-35b with success.

What is ground?RF ground and the ground plane, how can I tell if I have a good ground? ground loops

A quarter wave ground plane for 70 cm

HFUnderground.com is dedicated to documenting longwave, mediumwave, and shortwave stations, including broadcasters, utility/military stations, pirate radio and spy numbers stations.

The resource provides an in-depth analysis of the W6NL 40m _Moxon Yagi_ antenna, utilizing a NEC-2 model to simulate its performance. It details the antenna's design parameters, including element lengths and spacing, and explores critical operational aspects such as feedpoint impedance, SWR across the 40-meter band, and radiation patterns. The document systematically presents the model's setup and the methodology for evaluating the antenna's behavior in different environments, including free space and over real ground. Performance data derived from the NEC-2 model illustrates the antenna's forward gain, front-to-back ratio, and beamwidth. For instance, the model predicts a free-space gain of approximately **6.5 dBi** and a front-to-back ratio exceeding **20 dB** at resonance. Comparisons are drawn between free-space performance and operation at various heights above average ground, demonstrating the impact of ground proximity on take-off angle and overall efficiency. The analysis also touches upon the antenna's bandwidth characteristics, indicating its suitability for the entire 40-meter band with acceptable SWR.

Presents the construction and performance characteristics of a **2-meter vertical Moxon** antenna designed by WB5CXC. The antenna utilizes 1/2-inch PVC and #6 copper ground wire for its physical structure. Performance data includes measured front-to-back ratio using a local repeater, demonstrating significant signal attenuation when rotated. The resource provides **antenna pattern** plots, with blue tracing the design at 146 MHz and red indicating performance at 148 MHz. Gain and SWR plots are also included, alongside a detailed diagram of the antenna's physical layout. The design emphasizes a good front-to-back ratio, aligning with modeling predictions.

Radial systems for elevated and ground mounted vertical antennas by SteppIR

Designing **Moxon Rectangle** antennas often involves an urge among builders to find simple "magic formulas" for element lengths. L. B. Cebik, W4RNL, argues against this simplistic approach, emphasizing that antenna dimensions do not scale linearly and are influenced by factors like wire size and height above ground. This resource presents a procedure for developing sensible design equations, starting with uniform-diameter elements and perfectly conductive materials, with adjustments for real-world materials like copper and aluminum. The core of the method involves judicious **NEC modeling** (versions 2, 3, or 4) to create a baseline dataset for regression analysis, ensuring models meet specific performance standards for gain, front-to-back ratio, and feedpoint impedance. The derived equations, presented as a BASIC program, allow for calculating Moxon dimensions (A through E) based on wire diameter in wavelengths and design frequency. W4RNL demonstrates the efficacy of these equations by designing and testing Moxon Rectangles for 7.15 MHz (AWG #12 wire), 28.5 MHz (1" tubing), and 146 MHz (0.125" rod). Modeled performance data, including gain, front-to-back ratio, and feedpoint impedance, are provided for both perfect and real-world materials, showing high efficiency and close adherence to design goals. The article also references a standalone Windows program by AC6LA that automates these calculations and generates EZNEC or NEC models.

Managing extensive QSO data efficiently requires robust logging software capable of handling diverse operational needs, from casual ragchewing to competitive contesting. HAM OFFICE provides a comprehensive solution for amateur radio operators, integrating essential logging functionalities with advanced features for analysis and award tracking. It supports detailed QSO entry, offers various display and evaluation options, and includes helpful functions to guide users through its interface, ensuring a smooth workflow for both new and experienced hams. The software's design emphasizes user-friendliness while incorporating a wide array of functions, making it suitable for different screen sizes and operating preferences. It features innovative databases for enhanced data protection, improved handling despite increased functionality, and significant speed gains from new background calculations. The program runs stably on Windows XP through 11 (32 and 64 bit) and offers a mobile app for QSO entry and analysis on _tablet PCs_ and smartphones. HAM OFFICE is widely adopted, with an estimated **80%** of German contests logged using the software, and it is utilized by amateurs in **58** DXCC entities. The program supports various aspects of amateur radio, including contest logging, detailed evaluations, and integration with internet resources and shack equipment. It also provides specific support for new license classes like DN9 and actively supports initiatives such as the recognition of _Morse Telegraphy_ as a cultural heritage.

A _Topfkreis_ antenna, also known as a "bicycle pump" antenna, is presented as a simple vertical design for the 70 cm band. This variant of the J-pole antenna is notable for not requiring a ground plane, simplifying deployment. The construction details specify using aluminum tubing for the radiating element, with precise measurements for the quarter-wavelength outer tube (32 mm diameter) and the three-quarter wavelength inner sliding tubes (10 mm and 8 mm). Feeding is via a 50-ohm coaxial cable connected 90 mm from the base of the central tube. This design can achieve a gain of **4 to 6 dB** when properly tuned using the adjustable radiating element. The article details the fabrication of a critical aluminum washer, suggesting a method using a hole saw and a drill press as a lathe for precise adjustment. The illustrated example is specifically for the 70-centimeter band, and the author, Pop, clarifies construction points in the comments, including material choices and assembly techniques, ensuring a robust build for VHF/UHF operation.

A 90-foot vertical antenna constructed from **aluminum irrigation tubing** is detailed, focusing on its innovative raising and lowering mechanism. The resource describes a **45-foot ginpole** system, allowing a single operator to erect or lower the antenna in minutes. It covers the mechanical design, including the pivot base, insulated joints for the tubing sections, and guy wire attachment points. The antenna consists of two 30-foot sections of 4-inch tubing and one 30-foot section of 2-inch tubing, stacked with the smaller diameter at the top. The electrical design incorporates PVC "condulet" boxes at the 30-foot and 60-foot points, housing relays to change the effective height for multi-band operation on 160, 80, 40, and 30 meters. Ferrite rod inductive chokes are used for DC control and to tune out gap capacitance. The antenna is fed with 1000 feet of open wire line, connected to a matching transformer comprising stacked toroids and a coaxial/toroidal balun. Grounding is achieved with a 3x3 foot grid of 16-gauge tinned copper wires with soldered crossovers.

Operational testing of a 10.07-meter portable HF vertical antenna, constructed from telescoping aluminum tubing (36, 32, 22, 17 mm diameters), yielded SWR measurements below 1.5 across multiple bands. Initial trials on 14.150 MHz showed an SWR of 1.6, while 7.075 MHz was problematic. Subsequent adjustments, including a 13 cm extension to the radiating element, improved performance, enabling operation on 6, 15, and 40 meters without a balun, and adding 12 meters with a balun. The design prioritizes portability, allowing transport in a standard vehicle and single-person deployment. Four 10.07-meter radials are connected at the base to enhance ground plane effectiveness. The article details the mechanical assembly, including custom adapters for tube transitions and a PVC sanitary tube sleeve for base insulation, ensuring robust field deployment. Final SWR measurements, documented with an _MFJ-259_ antenna analyzer, confirm operational ranges: 6.800-7.500 MHz (SWR < 1.5), 20.800-22.500 MHz (SWR < 1.5), and 48.800-51.500 MHz (SWR < 1.5) without a balun. With a balun, the antenna achieved SWR < 1.5 on 13.750-15.000 MHz and 24.890-28.350 MHz, demonstrating its versatility for portable _DXpeditions_.

Monitors the space weather parameters essential for HF radio, including SSN/SFI, Ap/Kp, X-ray/Proton flux, and Auroral activity. IonoProbe downloads near-real time satellite and ground station data, stores information for future use and displays it in a user-friendly way.

A Grounding Q&A by ARRL web

The page discusses Axial-Mode Helical Antennas, focusing on turning helical antennas over perfect ground and modeling helices in NEC-2 for optimized design. It covers topics such as high-gain performance, broadband, impedance matching, radiation pattern, feedline, balun, near field, far field, and DIY applications.

This HALO design is not ground dependent and can be mounted atop a section of PVC.

Presents a construction project for a linear-loaded 40-meter rotatable dipole, detailing the design evolution from mid-element coils to 300-ohm twinlead loading. It covers material selection, including repurposed fishing poles and EMT conduit, and outlines the assembly process for the antenna elements and mounting plate. The resource provides specific measurements for element lengths and linear loading sections, along with SWR plots demonstrating the antenna's resonance at 7.035 MHz with a 1.1:1 SWR, and bandwidth up to 7.120 MHz below 2:1 SWR. The article documents the antenna's performance during various RTTY and CW contests, including the SARTG RTTY and SCC RTTY contests in August 2006, and the ARRL DX CW and CQWW WPX RTTY contests in February 2007. It reports successful operation at 500-1000W, noting improved performance after replacing a faulty coax cable. Specific DX contacts from British Columbia, including stations in Europe and South Africa, are listed, illustrating the antenna's capability despite its shortened length and relatively low height of 55 feet. The content highlights practical considerations such as weatherproofing the connections and supporting the fiberglass elements to prevent sagging. It also includes a brief comparison to an inverted-V at similar height and a ground-mounted vertical, noting the rotatable dipole's quieter reception. The author shares insights into the iterative design process and tuning adjustments made to achieve optimal resonance.

A Half wave antenna has a high impedance feed point. This can be matched using a 1/4 wave stub matching section and converts the 40m vertical into an L-shaped 20m J-Pole antenna. The 300 ohm feeder used for this purpose must be kept away from the ground.

Lowering an NVIS or N.V.I.S. antenna very close to the ground enhances NVIS operation

Demonstrates the design and construction of a compact, portable multi-band mini-delta loop antenna, specifically optimized for /P (portable) operations from remote locations like Scottish islands. The resource covers the theoretical underpinnings of half-wave loops, contrasting closed and open configurations, and then details the application of a folded dipole principle to achieve a 50-ohm match for direct coax feed. It presents empirical formulas for calculating element lengths, considering the velocity factor of common wire types, and provides a detailed example for a 20m (14.175 MHz) version. The article includes a comprehensive table of dimensions and allowances for a five-band (20m, 17m, 15m, 12m, 10m) mini-delta beam, along with construction hints for the central support and balun. It specifies a 1:1 trifilar balun wound on a ferrite rod and describes the antenna adjustment process using an _MFJ-259B Antenna Analyser_. Initial test results indicate an SWR of 1:1 at resonance and a bandwidth of approximately 240 kHz on 20m, even at a low height of five feet above ground. The distinctive utility lies in its focus on a practical, easily deployable beam antenna for portable DXing, offering a viable alternative to more complex or larger arrays.

Will we ever be able to dispel the myths? Steve Katz, WB2WIK/6

The Vee Beam antenna project presents a versatile solution for hams, enabling operation across all eight High Frequency bands (80m to 10m) with significant gain on 20m to 10m. This easy-to-construct antenna utilizes two long wires at an angle, enhancing directional performance and minimizing ground losses. With a low visual profile, it is discreet and effective for various applications. The design allows for optimal leg lengths and included angles, ensuring robust performance while maintaining simplicity in construction and operation. The V Beam antenna is an aerial that you can use on all eight High Frequency amateur bands (80, 40, 30, 20, 17, 15, 12 and 10m) with an antenna tuner, and which gives significant gain on the five bands from 20 to 10 meters band.

One of the most useful antennas in the repertoire is the Marconi or quarter wave grounded vertical antenna. Its invention made it possible to halve the length of antennas, simplifying communications, especially at HF and below.

This QRZ.com callbook entry by DL6GD details the construction and performance of a **40m/80m Morgain folded dipole antenna**. The resource includes a schematic diagram, construction photos, and tuning notes. The antenna, with a total length of **20.30m**, was mounted at a height varying from 4m to 6m above ground. Construction utilizes 0.75 sq mm transparent insulated copper wire, with Plexiglas spreaders (5mm thick, 70x10mm) spaced at 25mm intervals, secured with hot glue. A waterproof junction box houses the feedpoint and balun. Tuning involved adjusting wire bridges for resonance on each band. On 80m, an SWR of **1.1:1** was achieved at 3.657 MHz, with an SWR of 2.7:1 at 3.580 MHz and 2.5:1 at 3.755 MHz, yielding a bandwidth of 175 KHz. For 40m, an SWR of **1.1:1** was measured at 7.100 MHz, with 1.5:1 at 7.000 MHz and 1.3:1 at 7.200 MHz, providing a 200 KHz bandwidth. DL6GD notes that 80m tuning exhibits slight height sensitivity, while 40m tuning is less affected by height or 80m adjustments. Long-term observations from 2014 and 2022 document SWR degradation due to environmental factors like spiderwebs and ice accumulation, which can cause HF-conductive paths between elements. DXZone Focus: Callbook Entry | 40m/80m Morgain Dipole | SWR Measurements | 20.30m Length

A ground plane antenna for 80 meters band

Overvoltage protection, Voltage stabilization, Grounding in wiring, Ground wire resistance

Ameritron Al-811H Tuning for Power/Dissipation/Linearity, and More Generally 811A Tube Amps in Grounded Grid

Notes on Axial-Mode Helical Antennas in Amateur Service. Helix Basics, Modeling Issues, and Short Helical Antennas Over Perfect Ground

Over 47 full-screen maps are available within _NAOMI_ (North American Overlay Mapper), a free Windows program designed for US and Canadian amateur radio enthusiasts. This mapping suite includes 9 backgrounds such as CQ Zones, ITU Zones, and ARRL Sections, along with 16 foreground layers like Counties, Areacodes, and Grid Locators. Users can calculate distances and bearings, track real-time mouse positions with continuous Grid-Locator data, and integrate with APRS for live station tracking via the FindU database. For a global perspective, the _Global Overlay Mapper_ (GOM) provides a world map, 8 continental maps, and 29 sub-continental maps, all with 12 active layers including Country Outlines, CQ/ITU Zones, and Prefix information. Both NAOMI and GOM offer feature-locate systems to jump to positions based on prefixes, capital cities, or Grid Locators, and provide customized beam headings and distance displays. The site also features _LogView_, a post-contest log visualization tool that analyzes Cabrillo-format logs by plotting QSOs on maps, supporting over 30 major contests like CQWW and ARRL DX, and allowing comparison with published results.

This 40 meter Inverted V antenna was tested and tuned at a height of 35 feet and proved excellent results. The ends of the antenna are about 11 feet above the ground. Article and video available

5/8 vertical groundplane antenna for six meters band

A bowtie antenna is a type of antenna that reputedly provides higher gain at lower radiation angles than a center-fed dipole antenna at heights considerably less than 1/2 wavelength above ground.

This online guide details the microphone pinout for the Kenwood TR-7950 transceiver, specifically addressing the wiring configuration for a dynamic mobile microphone with a **500 Ohm** impedance. It provides a pin-by-pin breakdown for the 6-pin microphone connector, identifying the function of each active pin. The resource specifies that Pin #1 is for the microphone audio (white wire), Pin #2 controls the _PTT_ (black wire), Pin #3 activates the memory down function (blue wire), and Pin #4 controls the memory up function (red wire). Pin #6 is designated as the ground connection, while Pin #5 remains unused in this configuration. The document focuses on the physical wiring necessary to restore microphone functionality to the Kenwood TR-7950, a transceiver capable of **45 watts** output on the _2m band_. It directly addresses the technical challenge of re-establishing correct electrical connections after microphone wires have been disconnected from the connector. The information facilitates proper microphone operation for simplex QSOs and other voice communications. DXZone Focus: Online Guide | Microphone Pinout | Kenwood TR-7950 | PTT Wiring

A 50-ohm 10W resistor forms the core of this portable QRP antenna, designed by _K0EMT_ for convenient operation on 160m and 80m. The construction involves soldering the resistor to a BNC connector, with one lead to ground and the other to the center conductor, then insulating the assembly. This minimalist design aims to provide a highly portable solution for low-band QRP operations, acknowledging the inherent trade-offs between antenna size and efficiency. Testing with an antenna analyzer revealed low SWR on both 160m and 80m, with a Yaesu FT-817 confirming good matching. While 40m and 30m showed higher SWR, the primary focus remains on the lower bands. The author successfully tested the antenna with **2.5W CW** output, demonstrating its practical application for QRP field operations where ease of deployment is paramount, even if it means sacrificing some **gain** compared to full-sized antennas.

Mobile antenna placement presents unique challenges for the amateur radio operator, often requiring compromises between RF performance and mechanical considerations. This resource from KV5R.COM offers practical insights into achieving effective installations, drawing on real-world experience with different vehicle types. It details how factors like ground plane availability, proximity to vehicle structures, and antenna type (e.g., **HF mobile**, **VHF/UHF mobile**) influence signal radiation patterns and overall system efficiency. The author discusses common scenarios, from sedans and SUVs to trucks and RVs, highlighting the impact of mounting locations such as the trunk lip, fender, or roof. Specific attention is given to minimizing RF interference and maximizing radiated power, crucial for reliable mobile communications. Understanding the interaction between the antenna and the vehicle's metallic body is key to a successful mobile setup, and this content provides a solid foundation for making informed decisions.

Improper grounding or earthing system can cause several unwanted RF interferences (RFI) to television sets, broadcast receivers, hi-fi sets and telephone sets. In this Article the author explain how to setup a proper radio shack grounding using coaxial cable and ceramic disc capacitor

Packet-Radio-Controller for amateur radio, CB and commercial applications. Data radios (transceivers), receivers and transmitters for high speed data communication Assemblies for satellite ground stations, special receivers and transmitters.

This Artificial Ground has been designed by Colyn Baillie-Searle GD4EIRP

The Resonant Feedline Dipole (RFD) HF antenna design utilizes a single piece of coaxial cable and a stranded wire section, forming a 1/4-wavelength radiator. This configuration, based on a 1997 ARRL Handbook design (page 20.17), functions by RF traveling on the inside of the coax shield and returning on the outside, creating the second half of the dipole. A choke wound into the feedline prevents RF current from flowing back down the feedline. Construction details include using RG-58a/u coax for a 75m version, with a 1/4-wavelength section of stranded wire soldered to the center conductor. The document provides choke dimensions for RG-213, RG-8, and RG-58 coax across 3.5 MHz to 28 MHz, specifying cable length and number of turns. Dipole dimensions are also tabulated for frequencies from 3.6 MHz to 28.4 MHz, listing overall length and individual leg lengths. Field tests included deployment near Bryson City at 5 feet off the ground and as a sloper during WCARS Field Day in Asheville, yielding successful local and regional contacts.

Windows program for analyzing vertical antennas. This program shows the resistance and reactance to be expected looking into a cylindrical metallic tower over a perfect ground. It gives a useful approximation of the values to be expected in a real-world situation.

Radio frequency systems require robust protection against transient voltage events, which can severely damage sensitive equipment. This resource details a range of **RF surge protection** devices, including models with DC Pass, DC Block, Bias T, and Ultra Low PIM characteristics, designed to safeguard critical infrastructure. It also presents various RF filtering solutions and interconnect components, emphasizing their role in maintaining signal integrity and operational continuity across diverse applications. The site provides information on products engineered for both RF and data line protection, highlighting their utility in preventing downtime and equipment loss. Specific product categories encompass coaxial protectors, grounding items, and fiber optic solutions, indicating a broad scope of application from amateur radio installations to industrial and telecommunications networks. Furthermore, the resource mentions the availability of NOM-certified products and offers same-day shipping for many items, underscoring a commitment to rapid deployment and compliance with industry standards.

A new look at the Ufer ground system by Chris Scott

The Cushcraft X7 Tribander assembly and installation manual (P/N 951470, 12/97) provides comprehensive instructions for constructing this 20-15-10 meter seven-element beam antenna. It details the sequential assembly of boom sections, individual elements, and the feed system, including the _MNX7 Matching Network_. The document emphasizes critical safety precautions regarding power lines and RF exposure, alongside recommendations for proper antenna system planning and grounding. Key sections cover verification of parts, detailed boom assembly using specific aluminum tubing (e.g., BA, BB, BC, BD, BE) and brackets, and element construction with various aluminum tube sections (e.g., EA, EB, EC, ED, EE, EF) and traps like the _15 Meter Director Trap_ (TB) and _10 Meter Director Trap_ (T9). It also specifies the use of _NOALOX® conductive lubricant_ for telescoping sections and hardware to prevent galling. The manual outlines the feed system assembly, which includes feed-straps (FL1, FL2, FL3), tuning-tube insulators, and the matching network. It also mentions the optional X740 40-meter add-on kit, which requires a separate coax feed. Detailed diagrams and parts lists with metric equivalents facilitate accurate construction and ensure the antenna performs as specified.