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calculates the dimensions and spacings of the elements needed to build a log periodic antenna, given tao, sigma and the lower and upper cutoff frequencies.

Plans, photos, electrical and mechanical design for this HF Log periodic antenna.

Dipole, Yagi, Vertical, Cubic quad, Log periodic, J-pole, coil, and transmission line design package for the Macintosh

Log periodic antenna design excel sheet file download, in italian.

Create - Reliable antenna and antenna rotators from japan. Manufacturer of amateur radio products, HF VHF UHF antennas, antnena towers, antenna rotors, HF Log Periodic Antennas, VHF UHF wideband amateur radio antennas

QRPPAL, developed by WB2QAP, functions as a freeware QRP logging application for Windows 3.1 and Windows 95, initially introduced at the 1996 Dayton Hamvention FDIM QRP symposium. The software integrates the original "Logger" program, which was specifically designed for ARCI contest dupe checking and logging, alongside versions tailored for NW-QRP, MI-QRP Club, and Colorado QRP Club contests. It is distributed as a self-extracting archive, _qrppal!.exe_, approximately 1.2 MB in size, which unpacks _qrppal.exe_ and _setup.exe_ for installation. The program's modular design incorporates extensive QRP-centric databases, covering ARCI awards, QRP club listings, QRP periodicals, kit/vendor directories, and detailed rig reviews, often with photos. Noted reviewer Bob Gobrick, _VO1DRB_, described it as a "QRP Internet Web Site in a box" due to its comprehensive data modules, which are also user-modifiable. Installation involves running _setup.exe_ to create batch files like _setup95.bat_, which then establish a c:\qrppal directory and deploy the program files. Users initiate the application by typing "qrp pal.tkn" after setup. The Colorado QRP Club contest version should be avoided due to specific first name exchange requirements not supported by that module.

A fractional bandwidth of up to 30:1 characterizes spiral antennas, making them highly effective across a very wide frequency range, often from 1 GHz to 30 GHz. The resource details two primary types: the **Log-Periodic Spiral Antenna** and the **Archimedean Spiral Antenna**, defining each with specific polar functions and illustrating their planar configurations. It explains that spiral antennas are typically circularly polarized, with a Half-Power Beamwidth (HPBW) of approximately 70-90 degrees, and a peak radiation direction perpendicular to the spiral plane. The content elaborates on critical design parameters affecting radiation, including the total length (outer radius) for lowest frequency, the flare rate ('a' constant) for optimal radiation versus capacitive behavior, the feed structure (often an infinite balun) for high-frequency operation, and the number of turns (typically 1.5 to 3 turns). It also discusses the theoretical impedance of 188 Ohms for Log-Periodic spirals, derived from Babinet's Principle, noting actual impedances are often 100-150 Ohms. The article presents a simple construction method for an Archimedean spiral, demonstrating VSWR and efficiency measurements. Measurements from a constructed spiral antenna show a VSWR that is fairly constant across the band, albeit with a mismatch loss of about 3 dB. The antenna efficiency remains around -5 dB (31.6%) across its operating range, indicating a decent wideband radiator despite opportunities for optimization.

This QST article describes the electrical and mechanical design process for two LPs that cover the HF bands from 10-30 MHz

This LPDA calculator is based on the design procedure as described by L. B. Cebik, W4RNL (SK) in the 21st edition of The ARRL Antenna Handbook.

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.

Log periodic Antenna for 23, 13 and 9 cm bands. The LPA was built according to a design by DC8CE and is used for amateur radio television

This project introduces the Loggi, a hybrid antenna merging the wide frequency coverage of log-periodic dipole arrays (LPDA) with the high gain and front-to-back ratio (F/B) of Yagi antennas. Traditional LPDAs span broad frequencies with moderate gain and low VSWR, while Yagis provide high gain and F/B over narrow bands. By analyzing high-Tau LPDA designs, it was found they could nearly match the gain of VHF/UHF Yagis while maintaining excellent patterns, F/B, and front-to-rear ratios (F/R). Optimizing specific elements for target frequencies (e.g., 144.1 MHz) led to the Loggi, which uniquely features all driven elements without passive directors or reflectors. This design effectively functions as a narrowband optimized LPDA, with front elements acting like Yagi directors and rear elements like Yagi reflectors, thus enhancing gain and directional characteristics while retaining broad frequency versatility.