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Automatic Position Reporting System windows program, allow monitoring of real time geographical information such as the position of vehicles, the status of weather, radio direction finding and more.

How High should my Dipole be? Dipole Antennas and the effect of height above ground. The effectiveness of a dipole antenna is influenced by its height above ground, determined by the intended use such as DX work, local communication, directionality, omni-directionality, and feed point impedance. Through EZNEC modeling, the study evaluates a 40-meter dipole's performance at various heights, from 7 to 560 feet. Findings reveal that lower heights enhance omni-directional local communication, while higher placements favor DX work with low-angle radiation. The study emphasizes the importance of defining operational goals to optimize dipole height and performance.

Presents a practical design for a **crossed-dipole turnstile antenna** specifically engineered for 2-meter Amateur Radio Direction Finding (ARDF) events. The author, WB6RDV, details a robust, omnidirectional, horizontally-polarized antenna, addressing the international ARDF rules requiring such characteristics at a height of two to three meters above ground. This contrasts with the vertical polarization often used in Southern California, highlighting the design's adherence to specific event requirements. The electrical design employs a classic crossed-dipole with a 75-ohm phasing section, resulting in a slight impedance mismatch and an SWR of approximately 1.3:1 with a 50-ohm feedline. Construction utilizes readily available and inexpensive PVC plumbing components and 1/8-inch bronze welding rod for elements. The guide provides step-by-step instructions for mechanical assembly, including drilling element holes at precise 90-degree spacing and preparing the RG-179 matching section. WB6RDV shares insights from his own build experience, discussing the use of plated brass versus aluminum spacers for element attachment and the effectiveness of crimping as an alternative to soldering. The document also covers final assembly, including the integration of ferrite beads as a choke balun and options for weatherproofing and alternative mounting configurations, emphasizing the adaptability of the design for other VHF bands through scaling.

APRS for Linux is a multifaceted system for use with packet radio by Hams, it allows the monitoring of real time geographical information such as the position of vehicles, the status of weather, radio direction finding and much much more. It envolves mapping, GPS tracking, packet radio, etc

WiNRADiO Communications, a division of Radixon Group, was established in 1996 to commercialize extensive research in radio communications. The company specializes in integrating radio and computing technologies, offering a diverse product range for government, military, security, and amateur radio enthusiasts. Their product line includes the WR-G65DDCe 'EXCALIBUR Sigma' HF/VHF SDR receiver, noted for its capabilities, and the G31DDC EXCALIBUR, recognized for its price/performance ratio in shortwave listening with improved AMS and Noise Blanker features. The company also produces the G39DDC series EXCELSIOR for serious monitoring, WR-G526e/G527e/G528e modular SDR solutions for high-performance applications like phase-coherent direction finding, and the low-cost WR-G305e/G305i VHF/UHF receivers. Professional counterparts, the WR-G315e/G315i, support APCO P25 decoders and trunking options. WiNRADiO's offerings extend to the PFSL-G3 field strength logging system for mobile signal coverage, advanced multichannel telemetry systems like the MS-8323, and specialized antennas such as the AX-31C Log-Periodic and AX-81S active HF antenna. DRM decoder software is available for G3 Series receivers, enabling clear reception of DRM broadcasts. The WSS-420 Weather Satellite Receiving System and various antenna rotators are also part of their product ecosystem. WiNRADiO supports multiple operating systems, with MacRadio for Apple Macintosh users and LiNRADiO for Linux developers, providing drivers and network receiver solutions like the RLX-810.

All about radio direction finding (RDF)

N6QAB Radio Direction Finding Web Site, DF vehicles, transmitters, sniffers, dopplers, TH-D7A

Reports a 404 error, indicating the requested online receiver resource is unavailable. The page explains that QSL.net hosts over 30,000 websites, each maintained by different individuals, and suggests contacting the website owner directly or performing an internet search to locate the content. It clarifies that QSL.net cannot assist in finding specific missing pages or files. The page also notes that QSL.net provides email and web services free of charge to amateur radio operators and organizations. It encourages donations to support these services, providing a link to more information on how to contribute. The content emphasizes the need for user support to maintain the platform's operations.

The **ARRL Contest Calendar** presents a detailed schedule of upcoming amateur radio competitions, encompassing both ARRL-sponsored events and significant non-ARRL contests. It provides essential operational details for each entry, such as specific operating periods, eligible bands, and permitted modes, enabling contesters to plan their participation effectively. The resource also links to official rules, soapbox reports, and QST results, offering a comprehensive overview of past and future contest activity. Users can navigate through monthly listings to identify contests of interest, with direct access to detailed information pages for each event. The calendar serves as a central hub for contest operators seeking to confirm dates, understand exchange requirements, and review post-contest analyses. Its utility extends to both seasoned contesters and those new to competitive operating, providing a structured approach to contest participation. The platform integrates various contest-related resources, including links to **Contest Corral** entries for non-ARRL events, ensuring a broad scope of coverage. This aggregation of information streamlines the process of finding contest schedules and associated documentation, making it a practical tool for the amateur radio contesting community.

Over 1.5 million US amateur radio call signs are managed by the FCC, and this online service assists operators in finding available vanity call signs. Users can specify desired **call sign suffixes** to narrow down search results, which are drawn directly from the current FCC database. The platform clarifies that some valid call signs, never previously held since online FCC record-keeping began, may not appear in search results; for such cases, a separate "call lookup" function is recommended to verify availability before applying. The service provides crucial guidance on the application process, noting that applications should generally not be filed before the indicated "Available Date" unless the applicant is a former holder or a close family member. It also dispels the common misconception that call signs are granted on a first-come, first-served basis on any given day. Instead, all applications received on a particular day are metaphorically "thrown into a hat," with a winner randomly selected. This mechanism ensures fairness in the assignment of highly sought-after **vanity call signs** across the US amateur radio community.

The HB9DHG Contest Calendar aggregates contest information, offering direct links to official rules and past results for various amateur radio competitions. It features a curated list of events, with a focus on HF and digital mode contests, ensuring that operators can quickly access relevant details for upcoming and historical events. The calendar is regularly updated to reflect the latest contest schedules and rule changes. Each entry typically includes the contest name, dates, and a direct link to the sponsoring organization's page, such as ARRL or DARC, where full regulations and scoring information are available. This resource streamlines the process of finding contest specifics, which is crucial for effective pre-contest planning and post-contest analysis. Validation and checking of contest information are emphasized, providing a reliable source for operators planning their contest activity throughout the year. The calendar supports both CW and SSB modes, alongside various digital modes.

For amateur radio operators engaged in **radio direction finding** (RDF) and **transmitter hunting** (T-hunting) activities, this resource provides a catalog of printed circuit boards (PCBs) for constructing various DF and foxhunt-related projects. The offerings include PCBs for 80-meter fox transmitters and receivers, UHF fox transmitters with audio recording capabilities, and several designs for general-purpose radio direction finders. Specific projects like the "Simple 80M ATX-80 Transmitter" and the "N0GSG DSP Radio Direction Finder" are listed, along with attenuator boxes and specialized components for Doppler DF systems. The catalog details PCBs for projects published in prominent amateur radio magazines such as *73's*, *CQ*, *QST*, and *PE*, indicating their origin and design pedigree. For instance, the "Montreal Fox Controller" is sourced from the *Homing-In* column by Joe Moell, K0OV. The resource also lists components for advanced Doppler DF systems, including main boards, LED display boards, and antenna switch boards, with options for programmed PIC microcontrollers. Pricing for each PCB is provided, allowing hams to acquire the necessary components for their DIY RDF endeavors.

Hidden transmitter hunting, often called fox hunting or Amateur Radio Direction Finding (_ARDF_), presents a unique challenge for radio amateurs. This resource details the _PicCon_ controller, a specialized device designed to automate the transmission of signals for such events. It integrates with a standard radio transceiver, functioning similarly to a packet radio TNC, by controlling the Push-To-Talk (PTT) line and injecting audio tones or modulated CW Morse code into the microphone input. The _PicCon_ unit is field-programmable using DTMF tones received via the radio, storing all settings in EEPROM for power-off retention. Its compact design and low power consumption (a few milliamps from a 7-35VDC source) make it suitable for remote deployment. An onboard LED indicates operational status, and a push-button allows manual start/stop of transmissions without DTMF. Typically supplied as a kit, _PicCon_ includes a PCB, components, and a comprehensive manual (available in HTML, RTF, and PDF formats). The kit provides a six-conductor interface cable, but users must supply radio and power plugs due to varied configurations. Byon, _N6BG_, developed this controller, which is available from the Byonics website.

The information in this article has come from many amateur sources, the most notable was from WA6TEY (sk 1985) Ray Frost, who was a pioneer of VHF Quad designs and one of the best Southern California Transmitter Hunters. Ray built hundreds two meter quads in single and paired configurations as well as his famous mobile radio direction finding quad.

Welcome to the Amateur Television Directory, the source for finding sites related to Amateur Television and Ham Radio. Find out where Amateur Television is being used in your state or country.

The RasHAWK team has used a Raspberry Pi as the basis for a networked RF sensor capable of supporting spectrum monitoring, signal intercept and direction finding (DF) operations.

Amateur radio direction finding, transmitter hunting web site from San Francisco. Triangulating a radio signal direction and plotting its bearing on a map. Hunters use doppler systems for tracking hidden transmitters anywhere in the san francisco bay area, fremont california

Radio Direction Finding products

This resource presents a domain name for sale, Grandicelli.com, which was previously associated with an HF-VHF-UHF-SHF digital monitoring site, Wavecom Decoder tools, Winradio and DRM decoders, a WD3000 Direction Finding System, Radioraft software, and a PFSL3000 Integrated HF-VHF-UHF signal monitoring system. The current page functions as a sales portal, providing information on the domain's price of $695, with an option for a 24-month payment plan at $28.96 per month with 0% interest. The page outlines the purchasing process, including quick delivery of the domain within one to two hours, and details the transfer procedure to registrars like GoDaddy. It also highlights customer testimonials regarding the ease and speed of domain acquisition through HugeDomains, emphasizing the 30-day money-back guarantee and secure shopping experience. The resource clarifies that only the domain name is included, with hosting and web design services needing to be sourced separately.

Demonstrates a range of specialized radio frequency equipment and consulting services for amateur and professional applications. The offerings include _Vector-Finder_ direction finding antennas, various test equipment such as _gate dip meters_ and RF sniffers, and communications receiving adjuncts. Additionally, the company produces satellite antennas for weather satellite reception, voice amplification devices like the _Flex-Mike_, and custom prototype circuit boards. The company's product line addresses needs for precise RF measurement, signal detection, and specialized antenna systems, particularly for direction finding and satellite communications. Their historical association with National Radio (HRO) suggests a legacy in radio technology. The site also highlights a subsidiary, Sierra Mountain Products, which offers outdoor recreational gear, indicating a diversification beyond core RF manufacturing.

Ham radio activities, from satellite operations, eme communications, dxing and contesting, qsling and direction findings, are just some of ham radio exciting activities

The Dilawri Cardiovascular Institute (DCI) is a prominent Canadian organization dedicated to advancing cardiovascular health through cutting-edge research, equitable patient care, and medical innovation. It integrates 16 core centers, including specialized units like the Centre for AI, Data Science, and Imaging, and the Centre for Heart Rhythm, to bridge research findings directly into clinical practice. Their mission emphasizes providing world-class cardiac care accessible to all patients, regardless of their geographic location, by employing disruptive innovation and creative strategies to reach individuals faster. The institute focuses on a team-based approach, ensuring patients receive the correct therapy at the optimal time for long-term well-being. DCI's commitment extends to continuous growth through education, pushing boundaries beyond standard care, and fostering a respectful, inclusive environment for both staff and patients. They lead industry collaborations to shape the detection, treatment, and management of heart disease.

Using APRS For Direction Finding

Designer and manufacture of Airborne Antenna & Radomes covering a range of applications. Products include vhf antenna ,uhf antenna,navigation antenna,comm antenna,blade antenna,vor/ils antenna ,L band antenna, direction finding antenna,DF antenna,vor,ils, IFF antenna on aircraft,aircraft antenna for airborne application.

A Tape Measure Beam Antenna for Radio Direction Finding based on WB2HOL design.

A 7 dB directional gain is reported for this portable VHF Yagi antenna design, which utilizes cut metal tape measure sections for its elements. The resource details the construction process for a 2-meter band antenna, emphasizing its ease of build and portability. It specifically mentions the design's suitability for radio direction finding (RDF), fox hunting, and communication with satellites and the International Space Station (ISS), highlighting its practical applications for amateur radio operators. The construction cost is estimated at under $20, with potential for even lower expense if salvaged materials like old tape measures and PVC pipes are used. The article references _Joe Leggio's_ (WB2HOL) original design, noting specific alterations made by the author. It also compares this design to other DIY Yagi antennas, including _FN64's_ 2-meter band and _manuka's_ 70-cm band tape measure Yagis, underscoring its unique combination of simplicity, portability, and effective performance with a 1:1 SWR achievable on the 2-meter band.

SPX Communication Technologies, operating under the TCI International brand, presents a range of radio frequency (RF) solutions primarily for government, defense, and commercial sectors. The offerings include advanced systems for spectrum monitoring, communications intelligence (COMINT), and high-frequency (HF) and medium-frequency (MF) broadcasting and communication antenna systems. Specific product lines encompass _Blackbird_ COMINT systems, _Scout_ spectrum monitoring receivers, and various antenna arrays designed for robust performance in challenging RF environments. The resource details the capabilities of these systems, such as wideband signal detection, direction finding (DF), and signal analysis, crucial for intelligence gathering and regulatory compliance. It also highlights the engineering behind their antenna designs, which are optimized for specific frequency ranges and operational requirements, including high-power broadcast applications and secure military communications. The information presented emphasizes the integration of hardware and software for comprehensive RF situational awareness. The company's focus on empowering partners to "Command the Spectrum" underscores its commitment to delivering critical tools for signal interception, analysis, and management across diverse operational landscapes.

How to homemade antenna to be used with a handheld on the aircraft band to locate noise sources

Amateur radio direction finding, transmitter hunting. triangulating a radio signal direction and plotting its bearing on a map. hunters use doppler systems for tracking hidden transmitters

Antenna Authority Inc. offers a wide assortment of directional, wideband antennas and other equipment specifically engineered for radio direction finding (DFing) and geolocation applications. Their product line includes _log periodic_, _cavity-backed spirals_, and _Yagi_ antennas, alongside covert antenna solutions for various operational requirements. The company emphasizes its expertise in designing and manufacturing specialized antennas for both overt and covert operations. Beyond standard offerings, Antenna Authority Inc. provides custom design services to meet specific client needs, focusing on tailored RF directional products. Their capabilities extend to developing antennas for vehicles and optimizing their operational performance in diverse scenarios. The firm is located at 3381 W. County Line Road, Douglasville, Ga. 30135-1145. Ferrel Bentley is associated with Antenna Authority Inc., which has been operating since at least 2005, as indicated by the copyright notice.

The Utah Amateur Radio Club - Radio Direction-Finding RDF

This resource indicates that the specific page detailing the RockMite QRPp Rig CW transceiver project, previously hosted by WY3A on QSL.net, is currently inaccessible. The QSL.net platform, which provides free web hosting services to over 30,000 amateur radio operators and organizations, confirms the file or page no longer exists. Users are advised to attempt direct contact with the website owner or utilize an internet search to locate the content. The platform's error message clarifies that QSL.net support cannot assist in finding individual missing pages due to the decentralized maintenance of its numerous hosted sites. It encourages reporting any missing files related to the QSL.net main site itself. Donations are encouraged to support the free email and web services provided to the amateur radio community.

Cambridgeshire England Direction Finding group

The K5BSA Venturing Crew 73 resource, intended for a ham radio club based in Richardson, Texas, currently presents a 404 "Page Cannot Be Found" error. This status indicates the original content, which likely detailed club activities, membership information, or amateur radio projects, is no longer accessible at the specified URL. The page provides general information about _QSL.net_ hosting services, noting it supports over 30,000 websites for amateur radio operators and organizations. The error message suggests contacting the website owner directly or using an internet search to locate the intended content. It also clarifies that QSL.net cannot assist in finding specific missing pages hosted by individual users, as each site is independently maintained. The platform offers its email and web services without cost to the amateur radio community. Despite the error, the page includes links to general QSL.net resources such as "About QSL.net," "The Help Page," and "EMail Mailing Lists." It also features a prominent "Make a Donation" option, emphasizing that while services are free, user contributions are encouraged to support the hosting infrastructure.

Samples and documentation on RDF setups

The HB9CV antenna calculator aids amateur radio enthusiasts in designing antennas for VHF and UHF bands. By inputting the working frequency, users can obtain crucial dimensions like dipole lengths and distances. The tool, based on the HFSS antenna model, provides data on impedance, VSWR, and gain, optimizing front/back radiation ratios. It includes tips for fine-tuning using a Г-matching balun and compensating capacitor, ensuring effective performance and minimal VSWR for enhanced radio communications and direction finding.

The Peilgruppe Neandertal, featured on Peilsport.de, actively promotes _Amateur Radio Direction Finding_ (ARDF), also known as fox hunting. This German group combines radio technology with outdoor sport, participating in regional and national ARDF events. Members access current ARDF schedules, competition results, and downloadable certificates directly from the site. The content highlights the adventurous spirit of ARDF, emphasizing the blend of technical skill and nature exploration. DL7ET and DR9P are noted callsigns associated with the group, indicating active participation from experienced operators. The site also covers related activities like Foxoring, a variation of ARDF that integrates orienteering with radio direction finding. This resource serves as a central hub for the Neandertal group's activities, documenting their involvement in a sport that challenges both physical endurance and radio proficiency.

Professional SDR Signal Analysis Tools - Khanfar Spectrum Analyzer offers specialized SDR software tools for signal analysis, including real-time FFT analysis and precise frequency selection. The website provides a range of software for signal monitoring, spectrum analysis, radio direction finding, and antenna systems.

About Amateur Radio Direction Finding events, sprint and Fox-Oring spcialities. Sprints are intended to bring ARDF nearer to the public and to attract potential sponsors and new athletes to ARDF. Foxoring encourages ARDF enthusiasts to improve their orienteering skills.

Chavdar Levkov, LZ1AQ, presents an experimental comparison of small wideband magnetic loops, building on his previous work on wideband active small magnetic loop antennas. His research focuses on increasing loop sensitivity by maximizing the short-circuit current, which is directly tied to the "loop factor" M = A/L, where A is the equivalent loop area and L is its inductance. Levkov's methodology involves reducing inductance and increasing area through parallel or coplanar crossed (CC) configurations, comparing these designs against a reference single quad loop of 1 m2 area. Experimental verification included testing three distinct loop types: a simple quad loop, two coplanar crossed (CC) loops, and eight parallel loops, all designed to have a total geometric area of 1 m2. Measurements were conducted at 1.8, 3.5, 7, and 10 MHz using a small transmitter 270 meters away, with a Perseus direct sampling receiver for precise signal level assessment. The results consistently showed that CC loops, particularly Loop 5 (two CC circular loops with 1.44 m2 total area), yielded significantly higher currents, up to 9.1 dB over the reference loop at 3.5 MHz, validating M as a reliable predictor of loop sensitivity. Numerical simulations using MMANA further corroborated the experimental findings, demonstrating an almost perfect correlation between the calculated M factor and the induced loop current for 15 different loop models. Levkov concludes that CC loops offer superior sensitivity for a given loop area, while parallel loops are advantageous for minimizing physical volume. Practical recommendations suggest using loops with an M factor greater than 0.5 uA/pT for quiet rural environments, and he provides a spreadsheet tool, WLoop_calc.xls, to aid in optimizing loop configurations for specific operational needs.

The Aziloop DF-72 antenna system provides 72 K9AY headings and 36 loop axes, allowing for rapid switching in 60 ms. It integrates a switchable 18 dB preamp, a 4-step attenuator (0-18 dB), and four 7-pole preselection filters to optimize receiver performance. The K9AY load is adjustable from 250 Ohm to 950 Ohm in 50 Ohm increments, offering flexibility for various receiving conditions. Control is managed via an intuitive Windows UI, supporting Local, Client, or Server modes, with headless remote operation possible through the built-in Ethernet Server. _Omni-Rig_ support facilitates auto-filter selection, PTT muting, and Rig-Sync functionality, enhancing integration with existing station setups. Designed by _GW4GTE_, the system utilizes a low visual impact, small-footprint antenna with orthogonal loops and an earth connection. It is suitable for general monitoring, co-channel station resolution, basic direction finding, and interference reduction across the VLF to HF spectrum.

This page presents a project involving attaching an amateur radio transceiver to an Arduino to create a 'fox' signal for radio direction finding practice. This project can be used to practice direction finding skills by locating a radio transmitter in a hidden location. The project involves transmitting the station ID using Morse code and can be a fun and educational activity for students or hobbyists interested in radio direction finding. The author shares their experience with radio direction finding and provides instructions on how to build the project using a Baofeng UV-3R radio and an Arduino Uno.

Mid Sussex ARS is an RSGB-affiliated club and meets at its headquarters in Burgess Hill on the 2nd and 4th Friday of each month. They organize various activities ranging from talks by members or guest speakers, evenings on the air using their shack's latest SDR equipment, training evenings and used equipment sales. As well as scheduled club nights, they run many outdoor activities throughout the year, including direction-finding contests, town days, social evenings and Special Event Stations. They even have their own free online training academy!