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Antenna modelling techniques and examples by W4RNL

Over 45 years of amateur radio experience inform the homebrew projects detailed on this personal website, with a particular focus on microwave frequencies. The site showcases a 24 GHz transverter and a more recent 47 GHz transverter, demonstrating practical construction techniques for extreme high-frequency operation. These projects often involve custom circuit design and careful component selection to achieve stable performance at millimeter-wave bands. Key projects include a _harmonic converter_ for frequency measurement and a tracking spectrum analyzer, essential tools for microwave experimenters. The site also documents a CW sidetone generator and a TX/RX sequencer, illustrating fundamental building blocks for radio equipment. Details on a digital frequency meter and an S-meter/dBm meter provide insights into test equipment construction. Specific achievements, such as a **24 GHz** tropo QSO with DK3SE in 2021, highlight the operational success of these homebrewed systems. The content reflects a long-standing dedication to self-sufficiency in amateur radio, providing practical examples for those interested in building their own gear.

Mirko Pelcl's extensive radio collection features numerous historical transceivers and receivers, with a significant focus on military communications gear. The collection includes notable examples such as the Wireless Set No. 19, various Cold War-era military radios, and even a rare WWII spy radio utilizing a Loewe 3NF tube. Visitors can explore detailed sections dedicated to sets manufactured before 1945, including those used for military exchange, and a separate category for post-1945 radios, particularly those from the former Yugoslavia. The site also delves into specific modifications, like a digital head conversion for the RU-20, and showcases a frequency counter built with a microcontroller. This personal archive provides a unique glimpse into the evolution of radio technology, from early vacuum tube designs to more modern solid-state military transceivers like the PRC-515. The content reflects Mirko's dedication to preserving and documenting these pieces of radio history.

RSCW demonstrates a Linux/Unix command-line utility engineered for **Morse code** decoding via a computer's sound card. It specifically targets the extraction of weak CW signals from noise, operating on 8-bit, 8000 samples/second audio input, typically from `/dev/dsp`. The program outputs decoded characters to `stdout`, supporting user-specified speeds in words per minute (WPM) and carrier frequencies. While effective for machine-sent signals, it exhibits a 2-second decoding lag and requires manual speed input, making it less suitable for general-purpose, real-time contest operation. The resource details the program's components, including `rscw` (the main decoder), `rscwx` (an X11 graphical auxiliary for spectrum and internal signal visualization), `rs12tlmdec` (a specialized decoder for RS-12 amateur radio satellite telemetry), and `noisycw` (a utility for generating noisy Morse signals for testing). Installation instructions involve downloading a `.tgz` file, compiling with `Make`, and requiring the FFTW library (and GTK 2.0 for `rscwx`). Performance is illustrated with a .wav file example of a 12 WPM, 800 Hz CW signal at 12 dB Eb/N0, showcasing RSCW's near-error-free decoding of a test message. The site provides command-line examples utilizing `sox` for audio conversion and `noisycw` for signal generation, inviting comparisons with other decoding software and human operators, particularly for weak signal conditions.

The EF0604S is a compact 4 elements yagi antenna plan for six meters band featuring 8.77 dBi gain and a front back gain of 17.89 dB. Article includes elements dimensions and spacing, along to pictures of some homebrewed examples.

The Buddipole website showcases a range of portable amateur radio antenna systems, including the **Buddipole**, Mini-Buddipole, Buddistick PRO, and BuddiHEX, designed for rapid deployment and multi-band operation from 40 meters to 2 meters. Each product page details specifications, operational modes (dipole or vertical), and compatible accessories like tripods, masts, and baluns. The site also features portable DC power management systems such as the PowerMini 2 and PowerPlus, which include integrated battery chargers and solar controllers, catering to off-grid or field day setups. Instructional videos demonstrate antenna assembly, tuning, and deployment techniques for various configurations, including the VersaTee vertical and Mini-Buddipole. Customer testimonials and DXpedition highlights, such as operations from Montserrat (VP2M) and Dominica (J38), provide real-world examples of the equipment's performance in challenging environments. The company, established in 2001, emphasizes modularity, versatility, and efficiency in its product line, all manufactured in the USA. Shipping information, a 30-day return policy with no restocking fee, and contact details for their Heber City, Utah facility are clearly presented. The site serves as a direct sales portal, offering a comprehensive catalog of antennas, power solutions, and components for portable amateur radio enthusiasts.

STSORBIT PLUS, usually known as STSPLUS, will track the space shuttle or any satellite for which orbital data (TLEs) are available. A brief description of the program and several screen capture examples follow the links for downloading the program files.

Constructing a compact, two-band magnetic loop antenna for HF operation, especially from constrained locations like a balcony, presents unique challenges. OK1FOU's design, inspired by DJ3RW's 50 MHz loop, addresses these by employing an unusual side-fed configuration and placing the symmetric, two-section variable tuning capacitor at the bottom of the loop, directly connected to the coax shield. The article provides specific material recommendations, including two 1-meter wooden pales and about 3 meters of thick loudspeaker cable, noting the high current (60A at 100W) in the loop. Construction steps detail forming two turns with a 5 cm gap, using a GDO to pre-tune the open loop to a frequency slightly above the desired highest band, and then integrating the tuning and coupling capacitors. For 10/14 MHz, an open loop resonance of 16-17 MHz is suggested. Practical experience with the 10 MHz band from a third-floor balcony in Prague (JO70GC) shows a 1:1 SWR across most of the band without an external ATU. While DX traffic was modest due to the urban environment, QSO examples with RA6WF, LA6GIA, G0NXA, and LZ1QK on 10 MHz are provided, demonstrating its operational capability.

Many antennas function because of common mode currents, rather than working in spite of them. Two popular examples are CFA and EH antennas. Another recent example, appearing in Antennex's compact antenna articles, is a thick stub "vertical" with no counterpoise.

Examines the historical landscape of "boat anchor" amateur radio equipment manufacturers, focusing on the technical innovations and market dynamics that shaped the industry from the pre-WWII era through the transition to SSB. It details the origins and key product lines of prominent U.S. companies like _Collins Radio Company_, _Central Electronics_, and _Barker & Williamson_, highlighting their contributions to receiver and transmitter design. The resource contrasts early AM technology with the advent of SSB, explaining the circuit changes required in receivers and the complete rethinking needed for transmitters. It discusses the impact of military contracts on company survival and the eventual shift towards smaller, self-contained transceivers. Specific examples, such as the _Collins R-390/URR_ receiver and the _Central Electronics 100V/200V_ broadband transmitters, illustrate the engineering prowess and design philosophies of the era, offering insights into their operational characteristics and enduring appeal among collectors.

A 100Ft wire antenna for the top meter band

A trifilar folded dipole antenna for 80 meters band

These instructions use simple, generally familiar examples of equipment types and are designed to help you find the adjustment that suits you best. If you are looking on how to adjust a morse key, bencher key, paddle or straight morse key, here you will find all instructions.

An Arduino APRS project based on the real time OS BeRTOS

This online article provides a list of individuals who hold or have held amateur radio callsigns, detailing their public recognition. The resource identifies specific callsigns such as **K1JT** (Joe Taylor, Nobel Prize in Physics), **W6OBB** (Art Bell, syndicated radio personality), and **JY1** (King Hussein of Jordan), linking them to their non-amateur achievements. It also notes operational statuses like _Silent Key_ for deceased operators and _lapsed callsign_ for inactive licenses. The article includes information on callsign changes due to vanity callsign programs and provides examples of individuals involved in specific technical areas, such as Percy L. Spencer (**W1GBE**), inventor of the microwave oven, and Jay Kolinsky (**NE2Q**), inventor of electronic sirens. It also references amateur radio involvement in _space missions_ for individuals like Owen Garriot (**W5LFL**) and Helen Sharman (**GB1MIR**). DXZone Focus: Online Article | Famous Hams | Callsign Status | Vanity Callsigns

A project of a bobtail-curtain antenna for 10 MHz

Examines Kiwa, a global entity specializing in **Testing, Inspection, and Certification (TIC)** services across diverse sectors. The resource details Kiwa's operational scope, which encompasses quality assurance, safety compliance, and sustainability solutions for industries such as Food, Feed and Agriculture, Digital and Cyber Solutions, Energy Transition, Industrial Services, and Medical Devices. It highlights the company's role in ensuring product, service, process, and system integrity through rigorous accreditation and notification processes, operating in over 35 countries worldwide. The content presents specific examples of Kiwa's engagement, such as food safety certification for HortaPronta in Portugal, explanations of the Digital Battery Passport requirements, and contributions to floating offshore wind energy development. It also outlines the company's approach to biological evaluation of medical devices according to **ISO 10993** and its commitment to ESG principles, as detailed in its online ESG magazine, Trace. The resource provides access to a certificate finder and a testing directory with over 3000 capabilities across 80 laboratories.

A wire dipole antenna for 80 meters band

This resource details the four primary functions of a ground system: lightning energy dispersion, equipment safety, RF return path provision for end-fed antennas, and management of induced RF currents. It clarifies that a ground system's effectiveness varies depending on its specific function, noting that a good lightning ground might not be an effective RF ground. The content emphasizes that proper antenna system design, including baluns and appropriate feedline lengths, often negates the need for an RF station ground to mitigate common mode currents or RFI in the shack. The article quantifies lightning energy, stating its peak is in the dozens or hundreds of kilohertz, with damaging energy extending to hundreds of megahertz, and currents reaching thousands of amperes. It recommends solid, wide, smooth copper surfaces for ground leads to achieve low impedance across a wide frequency range. The author, W8JI, shares practical insights from his station, which includes two 300-ft towers and four 130-ft wire verticals, detailing his use of common point grounds and _DX Engineering RR-8 HD_ antenna switches for lightning protection without coaxial surge protectors. Specific examples of antenna systems prone to common mode current problems are listed, such as random wire antennas without proper feedline lengths and off-center fed dipoles. The text also explains how a ground screen or radial system can reduce local noise sensitivity for vertically polarized antennas by covering the lossy earth.

High pass filter schematics for TVI and examples of finished filters

Decibels: dB, dBA, dBC, dBV, dBm and dBi? What are they all? How are they related to loudness, to phons and to sones? This page describes and compares them all and gives sound file examples.

The MEL PICBASIC Forum serves as a community hub for users of Micro Engineering Labs PICBASIC compilers, facilitating discussions related to PIC microcontroller programming. It features dedicated sections for various compiler versions, including mel PIC BASIC, mel PIC BASIC Pro, and PBP3, each containing numerous threads and posts detailing specific programming challenges and solutions. The forum also provides areas for frequently asked questions, general PIC BASIC discussions, and commercial assistance requests. Specific sub-forums address advanced topics such as PBP Extensions, Code Examples, and AI and PICBASIC, offering insights into extending compiler functionality and integrating artificial intelligence concepts. Furthermore, the platform includes sections for Data Communications, covering USB, I2C, 1-Wire, GSM, and serial communications, which are critical for interfacing PIC microcontrollers with external devices. A dedicated area for PIC Programmers allows for discussions on programming hardware and techniques. The forum's utility is enhanced by its extensive archives of user-contributed solutions and examples, which can assist hams in developing microcontroller-based projects for radio applications. The platform's structure supports knowledge exchange among hobbyists and professionals working with PIC microcontrollers.

The resource provides specific information regarding amateur radio operations from various French islands, focusing on geographical and visual data. It includes photographic documentation of locations and detailed maps, which are crucial for operators planning DXpeditions or seeking to understand the unique challenges and opportunities presented by island activations. The content aims to support enthusiasts interested in rare grid squares and IOTA (Islands On The Air) awards. While currently under maintenance, the site's stated future enhancements include QSL card examples, which would offer practical insights into confirmation processes for these specific entities. The emphasis on French islands distinguishes it from more general DX resources, providing a concentrated body of information for a niche but active segment of the amateur radio community, particularly those pursuing island-specific operating awards.

This article includes an online calculator for a 3 element Yagi Antenna. The formula and basics theory of Yagi Antenna are also explained with examples.

The Cabrillo log format specifications, examples and templates.

Presents construction details for Moxon antennas, specifically focusing on 10-meter and 17-meter band configurations. It covers practical aspects of building these directional wire arrays, including element spacing, feedpoint considerations, and material choices for optimal performance. The resource emphasizes homebrewing techniques suitable for amateur radio operators. Discusses the advantages of the Moxon rectangle design, such as its compact footprint compared to a full-size Yagi and its favorable front-to-back ratio. It provides insights into achieving proper impedance matching and structural integrity for portable or fixed installations. The content includes photographic examples of constructed antennas. Explains the iterative process of tuning and optimizing Moxon antennas for specific frequency segments within the 10m and 17m bands. It offers guidance on minimizing SWR and maximizing gain, drawing from real-world building experiences to assist constructors in replicating successful designs.

Operating magnetic loop antennas requires careful consideration of RF safety, particularly regarding near-field magnetic field intensity. This resource presents calculations for magnetic field strength (H-field) at various distances from a magnetic loop, emphasizing that the H-field is significantly higher than the E-field in the near-field region due to the inductive nature of the radiating element. It provides specific formulas and examples for determining safe operating distances based on power levels and loop dimensions, crucial for compliance with RF exposure limits. The analysis compares calculated H-field values against FCC and ICNIRP maximum permissible exposure (MPE) limits for controlled and uncontrolled environments. It demonstrates that even at QRP power levels (e.g., 5W), the H-field can exceed MPE limits within a few feet of the antenna, necessitating greater separation distances than often assumed for electric field considerations. The practical application of these calculations helps amateur radio operators configure their stations to ensure personnel safety and regulatory compliance when deploying compact, high-Q magnetic loop antennas.

This resource examines the appropriate use of /M (mobile) and /P (portable) suffixes in amateur radio callsigns, specifically within the context of the UK Amateur Radio Licence. It addresses common ambiguities and challenges in determining operational status, such as operating from a summit or while walking. The discussion references the licence version in force before February 21, 2024, noting that while current regulations recommend but do not specify suffix use, the prior definitions remain relevant for understanding common practice. The content dissects key sections of the licence, including "Notes to the licence" (d)(i-iii) which outlines /A, /P, and /M usage based on location, and "Temporary Location" (jj) which defines /P operations. It also clarifies "Mobile" (17(1)(x)) as operating in or on a vehicle, on a pedestrian, or on a vessel on inland waters. The author provides examples and recommendations for choosing between /M and /P when both might apply, such as when operating from a parked car with a deployed mast or using a handheld on a summit. Historical notes from M1MAJ, G8ADD, and G6MZX are included, tracing the evolution of suffix rules from pre-BR68 days to the 1977 licence version. These historical perspectives highlight how past regulations have influenced current interpretations and persistent myths regarding /M usage. The resource emphasizes making an informed choice based on the licence and communicating the station's operational circumstances clearly.

Alternate means of raising your tower with readily available boat and engine hoists. Examples of working tower hoists with links to manufacturers.

A 38-foot Tristao Tower, similar to the U.S. Tower HDX538, was installed twice by the author, first in 1980 and then reinstalled in 1989. The resource details the challenges of self-performing heavy construction tasks like breaking concrete and digging a 3' x 3' x 6' deep footing, contrasting it with hiring professionals for the second installation. It highlights the financial and physical costs associated with DIY tower foundation work, noting a rebar cage cost of $65 in 1980 versus $150-$175 today, and the expense of tools for bending rebar. The content emphasizes the critical importance of obtaining building permits, recounting how a permit in Buena Park, California, nullified a neighbor's complaint about TVI. It also discusses the necessity of adhering to local building codes, such as the 1975 UBC and the subsequent 1985 UBC recertification requirement, which reduced the allowed antenna wind loading from 30 square feet to 20 square feet for the author's _KT34A_ Yagi. The footing depth also increased from 6 feet to 6.5 feet under the newer code. Practical advice includes hiring licensed contractors for specialized work, delaying antenna installation for a month after raising the tower, and verifying buried utilities before any excavation. The author provides specific examples of utility location services like _DigAlert_ in California, underscoring the legal and safety implications of neglecting this step. The narrative is grounded in personal experience, offering a realistic perspective on tower projects.

D-star videos, introduction to d-start, real examples on YouTube

PEP RF output power measurement, and examples RF output power measurements

The SETI League, Inc., founded in 1994, focused on participatory science, developing technology to seek definitive answers to the question of extraterrestrial intelligence. The organization operated in five dozen countries across all seven continents, maintaining the quest for cosmic companions through the efforts of its 1500 members. Although the organization shuttered its virtual doors after thirty years in 2024, the website remains for educational and historical purposes, documenting past research and activities. Key technical resources include the _SETI League Mini-Manual_ for constructing a 12 GHz radio telescope under $200, and software like _SETIFox for Windows_ and _Radio Eyes_ for radio astronomy sky viewing. The site also features _Project Argus_ detections, moonbounce signal detections, and space probe signal detections, providing concrete examples of amateur radio astronomy applications. Publications such as the quarterly newsletter _SearchLites_ and various articles by Dr. SETI (H. Paul Shuch, Ph.D.) are available, alongside information on the Third Penn State SETI Symposium in 2025. The site also offers insights into hydrogen line emission observations, presented in time domain, frequency domain, waterfall, and surface plot formats.

Wideband receiving phased arrays with small electric or magnetic active wideband elements are discussed in details. Practical results and examples are given.

Presentation about Practical Antenna Modeling Using the NEC Codes with examples of HF wire antennas and 4NEC2. How to define and edit the models, Running the simulations, Work some examples, Variables usage, Deal with Feed Lines and ground

QRSS pictures and examples from IW0HK ex IW1CXZ

The **HamRacer** voice keyer, a Windows-based application, is showcased in this video, illustrating its utility for radio amateurs participating in SSB contests. It functions as a synthesized PC-based voice keyer, specifically designed for HF and VHF SSB contest operations, allowing operators to transmit pre-recorded or text-to-speech generated messages during rapid-fire exchanges. The demonstration includes actual recorded QSO examples from a contest, featuring contacts with stations such as SP6OWA, S57O, OK1IEI, 9A1DL, OE1PAB, OK1GTH, and 9A1E. These examples highlight the software's practical application in a live contesting environment, demonstrating how it facilitates contest participation for operators who might otherwise face challenges with traditional voice keying. The resource provides a direct look at the software in action, emphasizing its role in promoting inclusivity within the amateur radio contesting community. It details the use of Windows SAPI for speech synthesis, a core component of HamRacer's functionality.

Always wanted to know what kind of sounds we hear, when listening to the radio? Here are some examples

The 2200-meter band (135.7-137.8 kHz) presents unique challenges for amateur radio operators due to its narrow 2.1 kHz bandwidth, low signal levels, and high noise. W1TAG explores various transmission modes suited for this demanding environment, highlighting that traditional voice modes like SSB and AM are impractical. Plain old CW serves as the baseline, demonstrating effectiveness across different modes, though signal-to-noise ratio (SNR) significantly limits practical speeds. The article notes that reducing CW speed below 5 WPM can improve copy, especially with computer-aided spectrum analysis software capable of decoding signals too weak for human ear reception. QRSS, or "CW sent slowly enough that speeds are best expressed in seconds per dot," is a key mode for LF work, with examples ranging from 3 seconds/dot to extreme 240 seconds/dot transmissions. _Argo_ by I2PHD is mentioned as a simple program for QRSS, enabling reception of signals like BRO, a Part 15 beacon, at a distance of **1100 miles**. Other modes discussed include Dual Frequency CW (DFCW), which uses frequency shifts to distinguish dots and dashes, and Binary Phase Shift Keying (BPSK), a phase modulation technique employing 0 to 180-degree phase flips. WOLF (Weak-signal Operation on Low Frequency), a specialized BPSK form by KK7KA, encodes 15-character messages into 960-bit packages, taking 96 seconds to transmit, and has demonstrated successful reception over **672 seconds** for a message from a 1-watt beacon. Further modes include PSK, FSK variations like JASON and MSK, and graphical modes such as Hellschreiber and Chirped Hell. The article concludes with a practical chart comparing the time required to send a simple message like "WD2XES FN42CH " across these diverse LF modes, offering valuable insights for operators planning contacts on the low bands.

Operating Morse code (CW) relies on a diverse array of **telegraph keys**, each with unique characteristics and historical significance. This resource presents a personal collection of such keys, offering visual documentation and details on various models. It features early Marconi keys from the 1900s, including specific models like the Marconi Air Ministry Key and Marconi Coastal Station Keys, alongside **Vibroplex** bugs and JRC keys. The collection also highlights rare items such as the Brown Brothers Magnetic Twin Paddle Key, the Eddystone Bug Key, and Swedish SRA Ericsson Keys. Enthusiasts can view examples of GPO Double Current & Single Current Keys, Navy NATO Keys, and specialized aircraft and maritime keys. The site includes information on historical training devices like the OMNIGRAPH and a Morse Inker from 1900, providing context for the evolution of telegraphy equipment. Additionally, the resource showcases unique items like the B2 Spy Set SOE Agents Key and a WW2 Junker U-BOAT KEY, illustrating the varied applications of Morse keys throughout history. The author, G0RDO, also shares details on a home-made paddle key and invites inquiries for acquiring interesting Morse keys.

Basic electronic circuit laws, capacitors, resistors, power circuits examples

Examples of absorbtive low-pass filters in which the unwanted high-frequency energy is separated from the wanted output and then dissipated in matched resistors

Presented is a historical collection of short-wave listening (SWL) QSL cards, primarily from the late 1930s and early 1940s, offering a glimpse into early international broadcasting and the technical pursuits of SWL operators like Les Miles during that era. The resource showcases specific QSLs from stations such as _Broadcasting Corporation of Japan_, _XGOY - The Central Broadcasting Administration_ in Chungking, China, and _Australian broadcasting ship, Kanimbla VK9MI_, each with reception dates and frequencies like 11.90MHz or 9.525MHz. It highlights the self-sufficiency of SWL enthusiasts who constructed and maintained their own radio and test equipment, evoking the sensory experience of vintage valve receivers. The collection provides concrete examples of international broadcast stations active before and during World War II, including _2RO3 - Rome_ and _WRUL - World Wide Broadcasting Foundation_ from Boston. Each QSL entry details the station, location, reception date, and often the frequency, such as 9.63MHz or 11.26MHz, allowing for historical verification of broadcast schedules. The resource also briefly mentions the operational details of the _VK9MI_ offshore radio station, directing readers to further information on its history. This compilation serves as a tangible record of global radio communication during a pivotal historical period.

Basic magnetic loop antenna examples and loop aerials theory explained. This article inclued some interesting tricks on building magnetic loop antennas and an usefull excell sheet to help compute magneti loop antennas calculating power efficiency from 10 to 40 meters band

The G5O Contest Group blog documents contest operations and related activities of the Stockport Radio Society. It covers various **HF** and **VHF** contests, providing insights into station setup, antenna configurations, and operational strategies employed during events. The content frequently includes post-contest analyses, discussing scores, propagation conditions, and technical challenges encountered. The blog entries detail specific contest participations, often featuring photographs of the operating environment and equipment used. It serves as a chronicle of the group's contesting history, offering practical examples of multi-operator station management and logistical planning for competitive amateur radio events. The group's focus on both local and international contests is evident through the range of events covered. Regular updates provide a continuous record of the group's engagement in the amateur radio contesting community.

Analyzing 433 MHz radio signals from common wireless devices, such as temperature sensors and remote controls, involves understanding **On-Off Keying (OOK)** modulation. This resource details the process of capturing these signals using a Software Defined Radio (SDR) like Gqrx and then visually inspecting the captured audio data in a sound editor such as Audacity. It differentiates between **Pulse Width Modulation (PWM)** and Pulse Position Modulation (PPM) encoding schemes, illustrating how to identify and decode binary data by eye based on pulse and gap durations. The article provides a step-by-step walkthrough for decoding a wireless thermometer's data, correlating bit patterns with known temperature, humidity, and channel values. It also demonstrates decoding an RF remote control's button presses, highlighting the constant and varying parts of the transmitted packets. The content further introduces automated decoding using tools like RTL_433, explaining its capabilities in parsing various device protocols and showing how to interpret its output, including modulation type and decoded data. Specific examples include analyzing Prologue sensor protocol specifications from RTL_433's source code and noting common operating frequencies like 433.92 MHz in Europe and 915 MHz in the US.

High Speed Multimedia (HSMM) radio, as introduced by John Champa, K8OCL, represents a significant advancement in amateur radio's digital capabilities, moving beyond traditional keyboard modes like packet radio. This initiative, driven by ARRL's Technology Task Force, focuses on developing high-speed digital radio networks capable of up to 20 megabits per second. HSMM primarily facilitates digital voice (DV) and digital video (ADV), enabling real-time video transmission from emergency scenes to an EOC without expensive ATV gear, often requiring only a laptop, a PCMCIA card, a digital camera, and a small antenna. The working group's initial efforts concentrate on cultivating microwave skills within the amateur community to build and support portable and fixed high-speed radio-based local networking, or **RLANs**. These networks prove invaluable for RACES and ARES organizations, as well as homeland security and other emergency communications. Field Day exercises and simulated emergency tests (SETs) are encouraged to hone skills in rapid site surveys and deploying broadband HSMM microwave radio networks, with examples like linking Field Day logging stations or antenna test results at the Midwest VHF-UHF Society Picnic 2003. Getting started with HSMM often involves adapting off-the-shelf **IEEE 802.11** (WiFi) equipment to comply with amateur radio regulations, typically operating in the 2.4 GHz ISM bands. While consumer WiFi gear has range limitations under Part 15 rules, proper setup under amateur regulations can extend coverage significantly, with test networks like the Hinternet achieving 5-15 mile ranges at 54 M bit/s using small mast-mounted dish antennas. Careful selection of equipment with external antenna ports, high transmit power, and low receive sensitivity is crucial, along with using low-loss coaxial cable like LMR-400 for optimal performance at these frequencies.

Fractional Wave Loops antennas are a sort of magnetic loop antennas that differs in several aspects from the standard ones. Author is now SK however in his page he posted several examples and interesting links

If you want to build your own common mode choke, this article explains how to measure the efficiecy of your choke before using it. In the examples has been used Amidon FT240-31 toroids.

Illustrates the fundamental principles of radio repeaters, detailing their role in extending communication range beyond line-of-sight limitations. It begins by defining _simplex communication_ as a direct radio-to-radio link, effective only when no obstructions impede the signal path. The resource then introduces the concept of a repeater (or base station) strategically positioned on elevated terrain, such as a mountain, to overcome geographical barriers. The article clarifies the repeater's operational mechanism: it receives a signal on one frequency and simultaneously re-transmits it on a different frequency, enabling users on opposite sides of an obstruction to communicate. This _duplex operation_ is likened to satellite communication for VHF propagation, but with a fixed terrestrial station. Specific examples of signal paths are provided, showing how a handheld radio transmits up to the repeater, which then relays the message down to another user, effectively bypassing obstacles like hills or large buildings.