The pa0rdt-Mini-Whip. -Mini-Whip.pdf (accessed 02/07/13). Bakker, Roelof. Constructing antennas around the male N type connector allows for mounting on the standard station Generic Antenna Mount. Fig 3: Fig 3 shows the model geometry, and the current distribution as a result of excitation by a 1V/m vertically polarised wave from 30° elevation. The article may contain links to articles on that site and which are no longer available. PA0RDT designed a compact active antenna for receiving over the range 10kHz to 30MHz. For the purposes of this article, the integral amplifier is considered part of the antenna system.
Otherwise, it is quite according to PA0RDT’s design. This kind of vertical whip is a full dipole and thus needs no ground plane. It generally works better several wavelengths above ground, hence the limitation normally to microwave bands.
Только обобщать эти результаты на все случаи явно бесполезно… Дата: 12 Фев 2007 03:03:19 # РЖУНЕМОГУ! 🙂 morzeУчастникс янв 2005Санкт-ПетербургСообщений: 4225 Дата: 12 Фев 2007 12:59:52 # Дата: 12 Фев 2007 19:03:03 · Поправил: 13466 (12 Фев 2007 21:24:36) # А как насчет схемки? Importantly, the antenna is VERY susceptible in the lower parts to coupling from noise sources like house wiring. It does not look like the isolated voltage probe that is commonly discussed. Я думаю, что Вы без труда найдёте все за и против.
Details of the assembly of the board and male N type connector with the water pipe bottom end cap is shown below including the aluminium mounting disc for the N type connector attachment. Though the PCB contains a smallish patch for the antenna, PA0RDT’s articles suggest that the patch should be extended by a whip of up to perhaps 1m, but he reports 300mm giving good S/N ratio. Scroll down the pdf for circuit diagram: -Mini-Whip.pdf. Chichester: John Wiley, 2007. Print. ^ Straw, R. D. The ARRL Antenna Book.
Дата: 11 Фев 2007 19:46:07 # На самом деле если бы всё было так замечательно — все бы давно бросили строить полноразмерные антенны на КВ и перешли бы к baby-кам. The board is connected via a very short section of coax to a male N type connector that is fixed to the base of the water pipe bottom end cap. The left side forms the antenna and the right side is ground and has a section of Vero-board glued to the back component connections.
With stationary whips, such as when they’re roof-mounted, an artificial «ground plane» consisting of several rods a quarter-wavelength long extending horizontally from the base of the whip is often used, which increases the low-angle radiation. But, that is not the case, the lower element is an arbitrary length of coax eventually connected to a ground electrode in PA0RDT’s article.
Однако в проффесиональных системах почему то этого не происходит. The antenna is often described as an E-field Probe Antenna as the high impedance front end amplifier measures the potential difference between the antenna plate (E antenna) and the grounded mast or coax screen. I’m trying to build a Mini Whip active antenna that receives 10KHz to 20MHz. But I’m having trouble finding the right components especially the transistors. It calls for a J310 and a 2N5109, which are both hard to find. Если у кого есть возможность, такая антенна описана в Electronics Desing ,1970,№8.p25-26.С тем что входной каскад должен иметь минимальные шумы согласен безоговорочно.
The demonstration supports the analysis above, the performance of the system without a significant length of feed line common mode conductor is seriously degraded, the feed line common mode conductor is a significant part of the antenna system. The kit was inexpensive (about US$20 IIRC) and arrived fairly promptly. This post is not intended to be an introduction to active antennas. It is supposed to show the realization of such a project from the schematics up to the finished device. It also shows how to choose equivalent parts as a replacement for those which are no longer available today. Whip antenna on car A whip antenna is an antenna consisting of a straight flexible wire or rod.
The integrated amplifier does not provide a conjugate match but it does allow obtaining a large part of the signal that is available to a matched load. Whip antennas for portable radios are often made of a series of interlocking telescoping metal tubes, so they can be retracted when not in use. Можно не верить в ее работу, но результаты наблюдений говорят о другом.Отзывы диэксистов, кстати, тоже.
The PA0RDT certainly works quite differently to the designer’s explanation, and the E-field magic just doesn’t hold water. As to whether it works well, that seems to be a personal matter for its users! Nevertheless, anecdotes abound that although the signal power captured with the antenna is less than a ‘big antenna’, the S/N is better. Весь фокус-покус, там в УВЧ двухкаскадном с разогнаным усилением….. а «штучка» длинной 45 мм это всего лишь ёмкость, на которую этот усилитель нагружен….. How does one go about choosing a suitable replacement? I’ve tried using to find similar transistors, but I’m not too sure what to compare.
Вот как пример обратной ситуации DDRR и её «продвиженец» Харченко. Larger versions mounted on roofs and radio masts are used as base station antennas for police, fire, ambulance, taxi, and other vehicle dispatchers. Very long, tall whip antennas such as may be used on military vehicles can be damaged by restricted height bridges, parking ramps, or drive-through service roofs.
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