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Query: active antenna
Links: 58 | Categories: 2
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What do amateur radio operators worldwide, think of their passion? What do we wish for? What are we frustrated about? How many of us are active, versus those that are taking a break? Do we have favorite radios, antennas, or even favorite cw paddles? Do we prefer one contest over another? The best way to find out is if we all participate in Ham Census. Join in and let all amateur radio operators know your thoughts "share your views" then you can find out what everyone else is thinking, in real time. Help shape the future of ham radio by participating in the world's most complete survey of amateur radio.
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This HF active antenna is a build of the PA0RDT Mini-Whip from a kit, it covers the entire HF band (3 to 30 MHz) and below (supposedly down to 10 kHz). It is powered by an external 12-15V supply, consuming about 50 mA.
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This project explores the construction and performance of an Alford Loop antenna as an alternative to a round loop. The Alford Loop, symmetrically fed at opposite corners, behaves like a small loop despite its larger size. Built using PVC pipes and secured with tire wraps, the antenna integrates an LZ1AQ active amplifier for optimal performance. With deep nulls in its horizontal radiation pattern and improved resonance characteristics, this design has significantly outperformed previous active antennas in reception quality.
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Showcasing German engineering, ANjo Antennen develops and manufactures a diverse portfolio of amateur radio and commercial antenna products. Their offerings span a wide frequency range from 1.8 MHz to 3000 MHz, emphasizing electrical and mechanical precision for longevity. The company actively participates in events like FUNK.TAG Kassel, providing opportunities for direct engagement and order pickup. ANjo's product line includes high-performance **Yagi antennas** optimized for Tropo and EME, along with multi-stacked Quad antennas designed for contest operations, featuring wide horizontal and narrow vertical beamwidths. They also produce circularly polarized satellite antennas, some with switchable LHCP/RHCP, leveraging their commercial satellite antenna expertise. Beyond amateur applications, ANjo provides flexible, custom antenna solutions for commercial sectors such as BOS, EMC measurements, and telemetry. Their commitment to quality is evident in the Premium-Line antennas, which utilize **1.4301 (V2A) stainless steel** for mast clamps and connectors, ensuring durability and corrosion resistance. They also offer end-fed HF multiband wire antennas, known for their compact footprint and discreet installation.
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Online interactive elevationmap can help radio amateurs by predicting signal propagation, optimizing antenna placement, planning coverage, ensuring line-of-sight, mitigating interference, and enhancing emergency communication. T
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The QRP Cluster provides a dedicated platform for _QRP_ (low power) amateur radio operators to self-spot their on-air activity. This web-based service allows users to post real-time information about their current operating frequency, modulation mode, equipment used, and transmit power. It facilitates QRP-to-QRP contacts and helps other low-power stations locate active QRP signals across various bands. Unlike general DX clusters, the QRP Cluster focuses exclusively on low-power operations, fostering a community for QRP enthusiasts. It enables operators to share details such as **5 watts** or less output, often specifying antenna types or unique portable setups. The platform supports the discovery of QRP stations for casual QSOs, contests, and award hunting, enhancing visibility for stations that might otherwise be overlooked on higher-power clusters.
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The Pikes Peak Radio Amateur Association (PPRAA) serves as an ARRL Special Service Club, providing a calendar of events and activities for its members and the wider amateur radio community. The resource details upcoming events such as the USS Pueblo Memorial Museum Ships Weekend activations, a Cubical Quad Antenna Workshop, LARCFest, and various hamfests including Dayton Hamvention and Duke City Hamfest. It also lists on-air activities like a FreeDV digital voice mode event on 10 meters, a Black Friday Simplex Event on 2M and 70cm, and a 10m event for Technician class operators, emphasizing SSB privileges from 28.300 to 28.500 MHz. The PPRAA's event schedule includes educational opportunities like a Technician Class and a Soldering Workshop, alongside social gatherings such as the PPRAA Picnic and Car Show. Past event summaries highlight successful activities like the 2024 Megafest Raffle, Winter Field Day, and multiple fox hunts utilizing frequencies like 147.420, 147.480, and 147.540 MHz. The club actively supports POTA activations, exemplified by their AF0S park activation at Cheyenne Mountain State Park, and participates in historical commemorations like the USS Pueblo Memorial operations, demonstrating a broad engagement across various amateur radio facets.
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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.