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Topic: Loading coil

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	Frequently Asked Questions
		Coil loaded antennas are preferred at lower frequencies as they help to avoid the use of excessively high voltage production at the output of the tuning unit and at the antenna feed point.
		For coil loaded antennas operating at low frequencies (100 kHz to 2 MHz) where they are considered electrically short, the main interest is usually in the strength of the radiation along the surface of the earth in the form of the ground wave.
		For coil loaded antennas the bandwidth is frequency dependant because the operating frequency determines the degree of coil loading necessary in the antenna.
	www.valcom-guelph.com /HTML/about_Valcom_G/faq.html (2301 words)

	Mobile antennas, short verticals, loading coil loss,and loading coil current
		It is determined by the ratio of termination impedance to stray capacitance from the coil to surroundings.
		In tank circuits or loading coils used with longer antennas or with capacitance hats, an optimum inductor is shorter and larger in diameter.
		One common myth is loading coil current is reduced by standing waves or by the fraction of "electrical degrees" the inductor "replaces" as it passes through the length of wire in the coil.
	www.w8ji.com /mobile_and_loaded_antenna.htm (6969 words)

	Loading Coils
		Although the Q of the coil is related (among other things) to the ratio of the coil length to the coil diameter, the stability of the coil construction is far more important.
		The DC resistance of the loading coil was 3.4 ohms.
		Prior to the legs being mounted underneath, this loading coil was originally mounted directly on the patio slabs, with the variometer connected at the earthy side of the loading coil.
	www.alg.demon.co.uk /radio/136/ldg_coil.htm (1995 words)

	TSCM - Time Domain Reflectometry (TDR) Analysis
		The large spike indicates a loading coil downline (around 500 foot away).
		(Loading Coils prevent the TDR pulse from passing).
		Note: Most law enforcement (and corporate) wiretaps are installed by installing a capacitively isolated device (or slave) at or behind a loading coil (typically 1-2 miles or more away from the target).
	www.tscm.com /tdr.html (605 words)

	Definition: loading coil
		Note 1: Loading coils inserted periodically in a pair of wires reduce the attenuation at the higher voice frequencies up to the cutoff frequency of the low-pass filter formed by (a) the inductance of the coils and distributed inductance of the wires, and (b) the distributed capacitance between the wires.
		Note 2: A common application of loading coils is to improve the voice-frequency amplitude response characteristics of twisted cable pairs.
		When connected across a twisted pair at regular intervals, loading coils, in concert with the distributed resistance and capacitance of the pair, form an audio-frequency filter that improves the high-frequency audio response of the pair.
	www.its.bldrdoc.gov /projects/devglossary/_loading_coil.html (186 words)

	Antenna Efficiency
		Depending on the requisite loading coil's position (bottom loaded or center loaded) the coil's Q factor, ground and stray losses, and resistive losses, the input impedance is closer to 25 ohms.
		In simple terms, the Q of a loading coil is the ratio of the inductance and the resistance of the coil measured at the resonant frequency.
		Coil Q is important because it directly relates to the efficiency of the antenna as a system.
	www.k0bg.com /eff.html (2472 words)

	Loading coil - Wikipedia, the free encyclopedia
		Loading coils are archaically known as Pupin coils after Mihajlo Pupin (especially when used for the Heaviside condition), and the process of inserting them is sometimes called pupinization.
		Loading coils inserted periodically in series with a pair of wires reduce the attenuation at the higher voice frequencies up to the cutoff frequency of the low-pass filter formed by (a) the inductance of the coils and distributed inductance of the wires, and (b) the distributed capacitance between the wires.
		A common application of loading coils is to improve the voice-frequency amplitude response characteristics of the twisted balanced pairs in a telephone cable.
	www.sciencedaily.com /encyclopedia/loading_coil (379 words)

	Loading coil (Site not responding. Last check: )
		In electronics, a loading coil is a coil that does not provide coupling to any other circuit, but is inserted in a circuit to increase its inductance.
		Loading coils inserted periodically in a pair of wires reduce the attenuation at the higher voice frequencies up to the cutoff frequency of the low-pass filter formed by (a) the inductance of the coils and distributed inductance of the wires, and (b) the distributed capacitance between the wires.
		A common application of loading coils is to improve the voice-frequency amplitude response characteristics of twisted cable pairs.
	www.serebella.com /encyclopedia/article-Loading_coil.html (256 words)

	Loading coil (Site not responding. Last check: )
		In electronics, a loading coil is a coil that does not provide coupling to any other circuit, but is inserted in a circuit toincrease its inductance.
		Loading coils inserted periodically in a pair of wires reduce the attenuation at the higher voice frequencies up to the cutoff frequency of the low-pass filter formed by (a) the inductance of the coils and distributed inductance of the wires, and (b)the distributed capacitance between the wires.
		When connected across a twisted pair at regularintervals, loading coils, in concert with the distributed resistance and capacitance of the pair, form an audio-frequency filter thatimproves the high-frequency audio response of the pair.
	www.therfcc.org /loading-coil-20986.html (178 words)

	Loading Coils
		Q of the coil is not that important, coil in this situation is the part of the radiating element, most of the current is at the base of the coil and surprisingly Q or form factor is not THAT important as measured and verified experimentally by W9UCW.
		Loading coils at the base or autotuners are the worst.
		The current in a typical loading coil in the shortened antennas drops across the coil roughly corresponding to the segment of the radiator it replaces.
	www.k3bu.us /loadingcoils.htm (2339 words)

	Loading Coils for LF
		Loading Coils for LF Loading Coils for LF This is a discussion on where to put the loading coil and does it contribute to radiation; and in what circumstances should a loading coil be screened - and how.
		The coil in a mobile antenna for the HF bands is considered to radiate as a linear conductor with a length equal to the length of the coil.
		The loading coil is not just a matching device, it is also a primary source of vector potential and it is the vector potential, rather than its offspring, the magnetic and electric fields, which is the fundamental source of electromagnetic radiation.
	web.ukonline.co.uk /g3ldo/coil.htm (1705 words)

	Tunable dipole antenna - Patent 4201990 (Site not responding. Last check: )
		In the case of a multi-band dipole antenna, in accordance with the invention, relays or solid state switching circuits connect pairs of taps symmetrically spaced from the mid plane of the loading coil to adjacent ends of linear radiating elements and the disc is located on the mid plane of the coil.
		Another object is the provision of a new and improved tuning arrangement for an antenna comprised of a loading coil and a disc, either electrically conductive or magnetically permeable, within the coil the plane of which is rotatable on a diameter of the coil.
		The disc 50 could of course be of magnetic permeable material conventionally used for tuning radio frequency coils in which case as the plane of the disc is moved to be perpendicular to the axis of the coil, the inductance of the coil increases.
	www.freepatentsonline.com /4201990.html (4157 words)

	[No title]
		This class explains how to properly handle and load coil onto the uncoiler, as well as describes how to thread the straightener and feed coil stock into the die area.
		A type of coil defect in which the coil wraps separate from one another and spread around the diameter of the coil.
		The press operator clips the retaining bands once the coil is loaded on the uncoiler.
	www.toolingu.com /class_class_desc.aspx?class_ID=400250 (1215 words)

	Short, Coil-Loaded, Ground-Mounted, Vertical or Slanting Antennas (Site not responding. Last check: )
		As the coil is moved higher up the antenna the current is more uniformly distributed along its length and radiation resistance increases until the coil nears the top of the antenna where Rr falls rapidly to near its no-coil value.
		Coil Q increases with physical size of coil and except for the effect of coil self-capacitance Q tends to be independent of height.
		When the difference in efficiency between a coil at moderate height and a base loading coil is less than 1 dB the inconvenience, cost or fragility of a high coil may not be considered justified and the antenna can be loaded with a coil incorporated in a tuning unit located immediately at the antenna's feedpoint.
	www.smeter.net /antennas/loadcoil.php (1082 words)

	Texas Bug Catcher ORDER - Work Sheet
		To raise the CAPACITY HAT farther away from the LOADING COIL for improved efficiency.
		Our NEW BANANA-PLUG Coil Taps and matching jumpers can be ordered singly or in kits to make loading coil and matching coil tapping simpler and quicker.
		COILS #440 (10 thru 40 Meters) 140.00 #480 (10 thru 80 Meters) 149.00
	www.texasbugcatcher.com /cata/tbcord.htm (343 words)

	FlashWebHost.com - Shorty Forty Antenna.
		It is a center loaded antenna with a loading coil at the center.
		The shield of 50 ohms coaxial cable is connected to the center of the coil.
		The center conductor is connected to 2 or 3 turns away from the center, to a point which gives the lowest SWR.
	www.flashwebhost.com /circuit/shortant.php (221 words)

	Hi-Q-Antennas for HF Ham Radio Mobile Operation KEYWORDS: W6HIQ, HA5CMG, VE7BOC, HF mobile antennas, mobile antenna, ...
		Therefore: It is a must that one keeps the LOADING coil clean and if the weather is foggy, wet, slushy, and/or dirty from road grimes, it is a good time to reduce RF power and protect your investment.
		Note: Hi-Q will honor the FIRST "lightning strike" and replace the coil at no cost to you until May 2005 after that we will replace the loading coil at cost plus shipping and handling.
		The heart of the antenna is the 5"x8" loading coil housed in a LEXAN SEALED housing and tuned by a 12 or 24 VDC gearhead motor.
	www.hiqantennas.com /news.htm (2760 words)

	MFJEnterprises.Com
		On the opposite end of the coil assembly, insert the remaining 3" brass rod through two adjacent turns on this end of the coil, through the brass coupling, and through the coil turns.
		Solder the coil turns to the brass rod, and then solder the brass rod to the coupling.
		Finally, on the end of the coil with the brass nipple (male end), solder a 6" piece of insulated wire terminated with an alligator clip.
	www.mfjenterprises.com /ultimatevertical.php (2762 words)

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