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Normal mode helix antennas offer a solution for HF mobile operators facing significant height restrictions, such as those parking in indoor garages with limited overhead clearance. This design, adapted from concepts typically applied to VHF/UHF rubber duck antennas, allows for extremely shortened HF radiators that remain effective for county hunting and general mobile operation. The resource details the construction of a 20-meter helix antenna, approximately 10 inches long, wound with #14 AWG THHN wire on a 1 1/2-inch CPVC form, mounted on a standard 3/8 x 24 antenna stud. Mark Herson, _N2MH_, shares his experience developing these antennas, including initial research from the _RSGB VHF UHF Manual_ and practical winding experiments to establish the relationship between turns and resonant frequency. He provides coil data for various frequencies, emphasizing that these measurements were taken with an _MFJ-259a_ antenna analyzer and are dependent on the vehicle's grounding system. Despite their shortened nature, N2MH confirms the antennas' operational effectiveness, citing contacts with KL1V in Alaska on 20 meters and E-skip contacts on 10 meters. The design prioritizes continuous deployment without removal, making it suitable for operators who frequently navigate height-restricted environments.

Examines the practical considerations and technical challenges of deploying mobile antennas for 10-meter operation, particularly for operators on the move. It addresses the inherently _lossy_ nature of shortened, loaded vertical antennas typically used in mobile configurations, encouraging hams to view these limitations as engineering challenges. The resource provides actionable advice on safeguarding vehicle electronics, selecting appropriate cabling like _RG-213_, and properly grounding antenna mounts to the vehicle chassis. Specific mounting strategies are detailed, including roof, trunk lip, and side-mounting for trucks and vans, along with their respective advantages and drawbacks. It emphasizes the importance of a robust ground plane and suggests methods for improving grounding beyond simple set screws. The article also touches on antenna choices, mentioning "bugcatchers" and "Hamstick types" as viable options for 10 meters. Furthermore, the guide transitions to stationary mobile operation, where antenna options expand significantly. It outlines how to deploy portable dipoles or 2-element beams from a parked vehicle, offering practical tips for assembly, storage, and mast guying using simple materials like a concrete block. It notes that a 5/8 wavelength height, approximately **20 feet** on 10 meters, often yields good short-skip and DX performance, even with a take-off angle above **20 degrees**.

The DXrobot, operational since 1999, offers a free, non-commercial service primarily for the VHF ham radio community. It specializes in automatic real-time E-skip warnings for **144 MHz** in both Europe and North America, delivered via email or SMS. Additionally, the system provides automatic aurora alerts for _50, 70, and 144 MHz_ openings through the same notification methods. Beyond real-time alerts, the DXrobot facilitates the reception of the latest DX-cluster spots via email, a feature useful for operators without immediate WWW or cluster access. The service also displays recent E-skip and aurora spots detected by the DXrobot on 50, 70, and 144 MHz, with updates every five minutes. Historical data includes lists of all DX spots from the previous day on 50, 70, and 144 MHz, updated daily. Key propagation data, such as MUF timeline, Solar X-rays, Geomagnetic Field, and Estimated Kp index, are also presented.

An easy to build multiband trapped dipole that can work well on short low bands for skip contacts

The santa cruz county amateur radio club. activities, the newsletter short skip, events, links and other happenings about amateur radio.

This is a group for CBers, Sidebanders, Amateurs and Freebanders. Items to be discussed are CB, Skip, Skeds, DX communications, SSB, export radios, Radio equipment, mods, ham radio, repairs, electronics, CW, PSK31, RTTY, digital, and different radio shops.

Automatic 144MHz E-skip Alerts for North America

Encouragement for Little Pistols, article originally written for and published in SKIP the monthly newsletter of the Fresno Amateur Radio Club

2 Meter Es spots detected by the DXrobot

Operating the UoSAT-2 (OSCAR-11) satellite, launched in 1984, presents unique challenges due to its age and current eclipse schedule. This resource provides a historical archive of news, telemetry data, and specialized software for decoding its 145.826 MHz FM beacon. It includes tools like _CTERM_ for terminal emulation and capture, and U2TM for processing ASCII telemetry, enabling hams to analyze the satellite's health and performance. The site also offers audio samples of the beacon and S-band signals, along with details on hardware and software decoders. Reception reports are actively solicited for the satellite's intermittent transmissions, which occur for less than an orbit every 21 days during its eclipse period. The site details how to process raw telemetry data, including instructions for skipping initial frames to improve decoding accuracy with U2TM. It also provides software like SATILL for predicting solar eclipses and tools for determining the satellite's spin period from magnetometer or solar array telemetry, offering insights into its operational status despite its advanced age.

Automatic 144MHz E-skip Warnings via Email for European Region

Roach pole vertical antenna for 40 and 30 meters band featuring good performance on short skips contacts compared to wire dipole

Demonstrates the construction of a high-power 6-meter (50 MHz) amplifier, specifically designed for demanding modes like EME, TEP, and multiskip Es. It details the use of a _GU-43B_ tetrode in a grounded-cathode configuration, emphasizing the need for stabilized grid voltage and input capacitance compensation. The resource provides a comprehensive schematic, power supply design, and practical considerations for component sourcing, particularly for high-voltage and high-current sections. The builder achieved an output power of **1250 watts** with an anode current of 0.65 amperes and 3200 volts anode voltage. The article also covers the physical construction within a modified P6-31 enclosure, outlining the internal layout for RF and power supply sections, and includes photos of the completed unit. It highlights critical safety precautions for working with high voltages and reactive currents up to **20 Amperes** in the P-network.

FSQ is a Fast Simple QSO mode designed specifically for HF. It works well under NVIS and sunrise/sunset conditions on the lower bands, and also works well for short skip and grey-line on higher bands and can be used also on VHF FM.

Thunderstorm effects on sporadic E propagation, Very long distance propagation in the 144 MHz band, Analysing the number of skips in multiple hop propagation

High Frequency (HF) radio propagation, particularly the phenomenon of "Skip," which enables long-distance radio contacts, is thoroughly explained for newcomers to the amateur radio hobby. The article begins by defining essential terms such as _radio signal_, atmosphere, troposphere, stratosphere, mesosphere, thermosphere, exosphere, and aurora, setting a foundational understanding for subsequent discussions. A significant portion of the content focuses on the ionosphere, identifying it as the primary driver of HF propagation. Its structure, including the D, E (E1, E2, E3), and F (F1, F2) layers, is detailed, along with how solar radiation influences these layers to refract radio waves back to Earth. The concept of "The band is opened!" is introduced, specifically noting refraction around **21 MHz**. The guide also touches upon ground waves, space waves, and temperature inversions affecting VHF/UHF propagation, contrasting them with the dynamic nature of ionospheric HF propagation. Factors like antenna polarization, takeoff angle, and the sun's solar cycle are mentioned as critical influences on signal path, with examples like 80-meter band propagation after sunset and 40-meter/20-meter bands offering near-constant propagation.

Understanding radio wave propagation is fundamental for effective HF communication, and this guide from the Galway Radio Club elucidates the principles behind _Near Vertical Incidence Skywave_ (NVIS) operation. It begins by contrasting NVIS with line-of-sight and surface wave propagation, highlighting its utility for reliable regional coverage, particularly in challenging terrains or within the skip zone. The document explains how NVIS leverages high-angle radiation, refracting signals from the ionosphere to return to Earth within a circular region, typically up to **650 km** (400 miles) from the transmitter. The guide delves into critical factors influencing NVIS, such as the _critical frequency_ (Fo) and the Maximum Usable Frequency (MUF), emphasizing their dependence on solar activity, time of day, and season. It provides practical advice on frequency selection, noting that 40 meters is often the highest daytime NVIS band, with 60 meters and 80 meters favored as darkness falls. The author, EI5DD, suggests using an ionogram for real-time propagation data, considering it more reliable than generic ham-clocks. Antenna considerations are also covered, recommending dipoles, inverted vees, or phased dipoles positioned 0.1 to 0.25 wavelengths above ground for optimal high-angle radiation. The document mentions mobile NVIS setups, including military configurations and commercial options like the Barrett Communications roof-rack antenna, which can cost around **£2000.00**. It concludes by reinforcing NVIS as an essential technique for national emergency communications, with 5 MHz (60m) and 80 meters being primary bands for daytime and nighttime operations, respectively.