US3889268A - Method of antenna tuning - Google Patents
Method of antenna tuning Download PDFInfo
- Publication number
- US3889268A US3889268A US447175A US44717574A US3889268A US 3889268 A US3889268 A US 3889268A US 447175 A US447175 A US 447175A US 44717574 A US44717574 A US 44717574A US 3889268 A US3889268 A US 3889268A
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- US
- United States
- Prior art keywords
- radio frequency
- antenna
- radiation
- output
- load
- Prior art date
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- Expired - Lifetime
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- 238000000034 method Methods 0.000 title claims abstract description 12
- 230000005855 radiation Effects 0.000 claims abstract description 34
- 230000008878 coupling Effects 0.000 claims abstract description 13
- 238000010168 coupling process Methods 0.000 claims abstract description 13
- 238000005859 coupling reaction Methods 0.000 claims abstract description 13
- 229910052732 germanium Inorganic materials 0.000 claims description 6
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims description 6
- 230000001939 inductive effect Effects 0.000 claims description 4
- 239000004065 semiconductor Substances 0.000 claims description 2
- 238000005259 measurement Methods 0.000 description 4
- 239000004020 conductor Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000001965 increasing effect Effects 0.000 description 2
- 238000010420 art technique Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000005686 electrostatic field Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
- H01Q9/04—Resonant antennas
- H01Q9/06—Details
- H01Q9/14—Length of element or elements adjustable
Definitions
- a fundamental form of an antenna is a single wire or radiator whose electrical length is equal to approximately half the transmitting wavelength.
- To obtain the most efficient transfer of energy from the transmitting source to the antenna system requires that the antenna be resonant at the desired frequency of operation and that the load resistance equal the radiation resistance of the antenna. Since the electrical input impedance of a dipole antenna at its resonant frequency is resistive the antenna system should be matched to the resistive value of the radio frequency generating source in order to obtain maximum performance from the antenna.
- the radiation resistance of the antenna can generally be defined as that value of resistance which when substituted for the antenna will dissipate the same amount of power that is radiated by the antenna.
- Prior art techniques used for adjusting antenna systems either physically or electrically require some means either of measuring the input impedance of the antenna or measuring the standing wave ratio. Normally various bridge measurement configurations have been used. These instruments are necessarily expensive for an accurate unit and require some radio frequency power for their operation.
- Standing wave measurements made at the antenna input terminals also have been utilized to determine if the radiation resistance of the antenna is equal to the impedance of the radio frequency source and transmission line. Comparative readings are made of the ratio of direct to reflected voltage from the antenna. The antenna is adjusted to bring the indicator reading on the standing wave measurement to maximum null or close to zero which indicates a minimum of reflected energy from the antenna. At this point the antenna is matched at the resonant frequency of the radio frequency generator.
- Tuning antennas by this technique requires a certain amount of radio frequency power delivered to the antenna in order that a satisfactory indication on the standing wave meter be obtained. Also it is necessary to switch the standing wave meter between forward and reflected energy which can be quite troublesome whenever tuning antennas designed to operate at relatively high frequencies.
- An object of the invention is to provide a method and apparatus system for tuning the physical length of an antenna system to its resonant length at a predetermined frequency.
- a variable radio frequency generator tunable in the range of the resonant frequency desired is coupled to a dummy load that has a resistance comparable to the theoretical radiation resistance of the antenna.
- a radiation responsive device is coupled to the radio frequency field for providing a direct current voltage output proportional to the magnitude of the field. This direct current voltage is coupled to an indicating instrument. The amount of direct current voltage on the indicating instrument is noted and the radio frequency energy is switched to the antenna.
- the antenna element to be tuned is either shortened or lengthened to bring the reading on the direct current indicator back to the original value that was observed when the radio frequency energy was connected to the dummy load.
- the antenna radiation resistance will be the same as the resistance of the dummy load and the antenna element will be at its resonant point.
- Block 12 represents a radiation energy device that is capable of being coupled to the radio frequency field.
- the radiation coupling device 12 generates a direct current voltage proportional to strength of the radio frequency field.
- This device may be of the type disclosed in US. Pat. No. 3,360,726.
- the device disclosed uses the effect of the radio frequency field to produce a measurable direct current voltage output.
- the radio frequency current flowing through wire 18 and 19 generates a radio frequency field about these wires.
- a germanium diode positioned closely adjacent a single wire will have induced therein, energy that is converted into direct current by the germanium diode. This inductive effect is believed to be due to the electro static field (E- field) of energy surrounding the wire and coupled to the germanium diode.
- Voltage meter leads coupled to either end of the germanium diode will give a direct current voltage indication on voltmeter 13. The magnitude of voltage will depend on the frequency of the frequency generator 11 and the value of the radio frequency output energy.
- Switch 15 is a good quality radio frequency switch, such as a coaxial switch since the conductors 17, 19 and 20 are coaxial cables.
- Dummy load 14 is preferably a resistive load that has low capacitive and inductive reactance.
- Load 14 is of such a value that it closely matches the radiation resistance to which the antenna will tune. Normally this resistance would be in the range of fifty ohms for matching the output impedance of the transmitter whichis coupled to the antenna, but this value may be changed to other desired values within limits of the resistance of the antenna element to be tuned.
- variable frequency generator is tuned to the desired resonant frequency of the antenna element 16.
- Switch 15 is connected to the resistive dummy load '14. The output of generator 11 is increased until a'substantial voltage indication is indicated by direct current voltmeter 13.
- the radiation responsive device 12 by induction from the radio frequency energy present in the wire from the generator 11 gives a voltage indication proportional to the energy flowing'throughthe dummy load 14.
- Switch 15 is activated to connect antenna element 16 to the radio frequency energy source 11.
- the indication on the voltmeter is brought to its original reading by increasing or decreasing the physical length of antenna element 16. Shortening or lengthing the antenna element 16 may be accomplished by various means known to those skilled in the antenna art. When the antenna element has been adjusted to cause the same reading on voltmeter 13 as obtained by the dummy load 14, the antenna, element is properly adjusted for that frequency.
- An antenna tuning system for adjusting the physical dimensions of an antenna to an electrically resonant length at a predetermined frequency comprising:
- a frequency generator means for supplying a variable radio frequency output in the range of frequencies at which the antenna will resonate
- measuring means electrically coupled to said radiation responsive means for providing an indication of direct current voltage output
- load means electrically coupled to receive a radio frequency output from said radio frequency radiation responsive means; and switch means electrically coupled to said radio frequency radiation responsive means and operable for selectively switching radio frequency energy between said antenna and said load means;
- the frequency generator is adjusted to give an output indication on measuring means at the resonant frequency of the antenna for tuning the antenna by comparing the indication on the indicating means as the switch means is operated between the antenna and the dummy load.
- radio frequency radiation responsive means comprises:
- a method of adjusting the physical dimension of an antenna radiation element to its electrically resonant length at a predetermined frequency consisting of:
Landscapes
- Details Of Aerials (AREA)
Abstract
A method and apparatus for adjusting the physical dimensions of an antenna radiating element to its electrically resonant length at a predetermined frequency by coupling a radiation sensitive device between a radio frequency energy source and a dummy load. A direct current meter is coupled to the radiation device to obtain a reading on the meter which is proportional to the radio frequency energy traveling to the load. The value read on the meter is noted and the source of radio frequency energy is switched to the antenna element which is to be tuned. The physical length of the antenna element is shortened or lengthened to bring the reading of the meter to the value obtained when the radio frequency energy was connected to the dummy load. At this point the antenna element has been tuned and its radiation resistance will equal that of the dummy load.
Description
United States Patent Peters June 10, 1975 METHOD OF ANTENNA TUNING Primary Examiner- EM Lieberman [75] Inventor: Carl L Peters, vista, Calif Attorney, Agent, or Fzrm-R. S. Sciascia; Roy Miller;
Robert F. Beers [73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC. [57] ABSTRACT [22] Filed: Mar. 1, 1974 A method and apparatus for adjusting the physical di- [21] Appl NO 447 175 mensions of an antenna radiating element to its electrically resonant length at a predetermined frequency by coupling a radiation sensitive device between a [52] U.S. Cl. 343/703 radio frequency energy source and a dummy load. A direct current meter is coupled to the radiation device 51 Int. Cl. GOlr to Obtain a reading on the meter which is proportional of Search to the radio frequency energy traveling to the load The value read on the meter is noted and the source of radio frequency energy is switched to the antenna [56] References Cited element which is to be tuned. The physical length of the antenna element is shortened or lengthened to UNITED STATES PATENTS bring the reading of the meter to the value obtained 2,365,207 12/1944 Moles 343 703 When the radio f q y energy was Connected to the 2,565,900 W116}, dummy load At this point the antenna element has OTHER PUBLICATIONS Hints and Kinks for the Radio Amateur: published by American Radio Relay League, 1968, pg. 110.
been tuned and its radiation resistance will equal that of the dummy load.
3 Claims, 1 Drawing Figure 15h l6 VARIABLE RADIATION FREQUENCY COUPLING SWITCH GENERATOR DEVICE l7 DUMMY VOLTMETER LOAD PATENTEIJJUH 10 I975 3. 8 89268 IN l2\ 5W 1e VARIABLE RADIATION FREQUENCY COUPLING SWITCH GENERATOR DEVICE |9 17 DUMMY VOLTMETER E LOAD METHOD OF ANTENNA TUNING BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an improved method and measurement system for quickly and accurately tuning the physical length of radiating antenna elements to a desired resonant frequency.
2. Prior Art A fundamental form of an antenna is a single wire or radiator whose electrical length is equal to approximately half the transmitting wavelength. To obtain the most efficient transfer of energy from the transmitting source to the antenna system requires that the antenna be resonant at the desired frequency of operation and that the load resistance equal the radiation resistance of the antenna. Since the electrical input impedance of a dipole antenna at its resonant frequency is resistive the antenna system should be matched to the resistive value of the radio frequency generating source in order to obtain maximum performance from the antenna. The radiation resistance of the antenna can generally be defined as that value of resistance which when substituted for the antenna will dissipate the same amount of power that is radiated by the antenna. When the radio frequency transmitter supplies energy at the resonant frequency the maximum amount of energy supplied to the antenna will be radiated into space. I-Ialf wave antennas in free space have a certain characteristic radiation resistance but the actual value of radiation resistance of any given antenna depends upon its configuration and the size and the proximity and character of nearby objects to the antenna. Because of these effects which detune the antenna, merely calculating the antennas resonant length will not insure its most efficient operation and it is necessary to use some measuring technique to determine the actual electrical length of antenna which will be resonant at the frequency of operation.
Prior art techniques used for adjusting antenna systems either physically or electrically require some means either of measuring the input impedance of the antenna or measuring the standing wave ratio. Normally various bridge measurement configurations have been used. These instruments are necessarily expensive for an accurate unit and require some radio frequency power for their operation. Standing wave measurements made at the antenna input terminals also have been utilized to determine if the radiation resistance of the antenna is equal to the impedance of the radio frequency source and transmission line. Comparative readings are made of the ratio of direct to reflected voltage from the antenna. The antenna is adjusted to bring the indicator reading on the standing wave measurement to maximum null or close to zero which indicates a minimum of reflected energy from the antenna. At this point the antenna is matched at the resonant frequency of the radio frequency generator. Tuning antennas by this technique requires a certain amount of radio frequency power delivered to the antenna in order that a satisfactory indication on the standing wave meter be obtained. Also it is necessary to switch the standing wave meter between forward and reflected energy which can be quite troublesome whenever tuning antennas designed to operate at relatively high frequencies.
SUMMARY OF THE INVENTION An object of the invention is to provide a method and apparatus system for tuning the physical length of an antenna system to its resonant length at a predetermined frequency.
This and objects herein after defined are met by the invention which relates to a method of tuning a radiating antenna element to its resonant length in a minimum of time and with relatively inexpensive equipment that is simple to operate and allows tuning of antennas operating at relatively higher frequencies with little. time, trouble and effort. A variable radio frequency generator tunable in the range of the resonant frequency desired is coupled to a dummy load that has a resistance comparable to the theoretical radiation resistance of the antenna. A radiation responsive device is coupled to the radio frequency field for providing a direct current voltage output proportional to the magnitude of the field. This direct current voltage is coupled to an indicating instrument. The amount of direct current voltage on the indicating instrument is noted and the radio frequency energy is switched to the antenna. The antenna element to be tuned is either shortened or lengthened to bring the reading on the direct current indicator back to the original value that was observed when the radio frequency energy was connected to the dummy load. When this point isreached the antenna radiation resistance will be the same as the resistance of the dummy load and the antenna element will be at its resonant point.
BRIEF DESCRIPTION OF THE DRAWING The only drawing in the case is a simplified block diagram representation of an antenna tuning apparatus constructed in accordance with the teachings of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Referring to the only drawing in the case, which shows a blocked diagram of various electronic devices coupled together for tuning an antenna element. Block radio frequency outputs. The output is coupled to the antenna element to be tuned via radiation coupling device 12 and switch 15. The conductors 17, 18 and 20 may be coaxial cables or other suitable means to conduct high frequency energy at a low energy loss.
. A switch is coupled between the antenna element 16, dummy load 14 and radiation coupling device 12. Switch 15 is a good quality radio frequency switch, such as a coaxial switch since the conductors 17, 19 and 20 are coaxial cables.
Dummy load 14 is preferably a resistive load that has low capacitive and inductive reactance. Load 14 is of such a value that it closely matches the radiation resistance to which the antenna will tune. Normally this resistance would be in the range of fifty ohms for matching the output impedance of the transmitter whichis coupled to the antenna, but this value may be changed to other desired values within limits of the resistance of the antenna element to be tuned.
In the tuning operation of the apparatus shown in the only figure of the drawing, variable frequency generator is tuned to the desired resonant frequency of the antenna element 16. Switch 15 is connected to the resistive dummy load '14. The output of generator 11 is increased until a'substantial voltage indication is indicated by direct current voltmeter 13. The radiation responsive device 12 by induction from the radio frequency energy present in the wire from the generator 11 gives a voltage indication proportional to the energy flowing'throughthe dummy load 14. Switch 15 is activated to connect antenna element 16 to the radio frequency energy source 11. The indication on the voltmeter is brought to its original reading by increasing or decreasing the physical length of antenna element 16. Shortening or lengthing the antenna element 16 may be accomplished by various means known to those skilled in the antenna art. When the antenna element has been adjusted to cause the same reading on voltmeter 13 as obtained by the dummy load 14, the antenna, element is properly adjusted for that frequency.
ingmethod used by the present invention is extremely simple to set up and permits accurate tuning by allowing small incremental adjustments of antenna element length. 1
Although the preferred embodiment has been described, it will be understood that within the purview of this invention various changes may be made in the 4 form, details, proportion and arrangement of parts, the combination thereof and made of operation, which generally stated consist in a device capable of carrying out the objects set forth, as disclosed and defined in the appended claims.
What is claimed is: v
1. An antenna tuning system for adjusting the physical dimensions of an antenna to an electrically resonant length at a predetermined frequency comprising:
a frequency generator means for supplying a variable radio frequency output in the range of frequencies at which the antenna will resonate;
meansresponsive to radio frequency radiation coupled to said generator output for supplying a direct current voltage output in proportion to the output of said radio frequency generator;
measuring means electrically coupled to said radiation responsive means for providing an indication of direct current voltage output;
load means electrically coupled to receive a radio frequency output from said radio frequency radiation responsive means; and switch means electrically coupled to said radio frequency radiation responsive means and operable for selectively switching radio frequency energy between said antenna and said load means;
whereby the frequency generator is adjusted to give an output indication on measuring means at the resonant frequency of the antenna for tuning the antenna by comparing the indication on the indicating means as the switch means is operated between the antenna and the dummy load.
2. The antenna tuning system of claim 1 wherein said radio frequency radiation responsive means comprises:
a'means of inductive coupling to the radio frequency energy for obtaining a direct voltage output that is proportional to the radio frequency energy.
3. A method of adjusting the physical dimension of an antenna radiation element to its electrically resonant length at a predetermined frequency consisting of:
feeding a radio frequency signal to a substantially resistive load; inductively coupling said radio frequency signal to a germanium semiconductor diode for generating a direct current signal that is proportional to the magnitude of said radio frequency signal;
coupling said direct current signal to an indicator for determining the magnitude of said radio frequency signal;
switching said radio frequency signal from said resistive load to said antenna; and
adjusting the physical length of said antenna element until the reading on said indicator isthe same as observed on said indicator when said radio frequency signal was connected to said resistive load.
Claims (3)
1. An antenna tuning system for adjusting the physical dimensions of an antenna to an electrically resonant length at a predetermined frequency comprising: a frequency generator means for supplying a variable radio frequency output in the range of frequencies at which the antenna will resonate; means responsive to radio frequency radiation coupled to said generator output for supplying a direct current voltage output in proportion to the output of said radio frequency generator; measuring means electrically coupled to said radiation responsive means for providing an indication of direct current voltage output; load means electrically coupled to receive a radio frequency output from said radio frequency radiation responsive means; and switch means electrically coupled to said radio frequency radiation responsive means and operable for selectively switcHing radio frequency energy between said antenna and said load means; whereby the frequency generator is adjusted to give an output indication on measuring means at the resonant frequency of the antenna for tuning the antenna by comparing the indication on the indicating means as the switch means is operated between the antenna and the dummy load.
2. The antenna tuning system of claim 1 wherein said radio frequency radiation responsive means comprises: a means of inductive coupling to the radio frequency energy for obtaining a direct voltage output that is proportional to the radio frequency energy.
3. A method of adjusting the physical dimension of an antenna radiation element to its electrically resonant length at a predetermined frequency consisting of: feeding a radio frequency signal to a substantially resistive load; inductively coupling said radio frequency signal to a germanium semiconductor diode for generating a direct current signal that is proportional to the magnitude of said radio frequency signal; coupling said direct current signal to an indicator for determining the magnitude of said radio frequency signal; switching said radio frequency signal from said resistive load to said antenna; and adjusting the physical length of said antenna element until the reading on said indicator is the same as observed on said indicator when said radio frequency signal was connected to said resistive load.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US447175A US3889268A (en) | 1974-03-01 | 1974-03-01 | Method of antenna tuning |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US447175A US3889268A (en) | 1974-03-01 | 1974-03-01 | Method of antenna tuning |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3889268A true US3889268A (en) | 1975-06-10 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US447175A Expired - Lifetime US3889268A (en) | 1974-03-01 | 1974-03-01 | Method of antenna tuning |
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| Country | Link |
|---|---|
| US (1) | US3889268A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100248649A1 (en) * | 2009-03-30 | 2010-09-30 | White Douglas W | Antenna with integrated tuning detection elements |
| US20140347250A1 (en) * | 2013-05-27 | 2014-11-27 | Fujitsu Component Limited | Antenna apparatus |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2365207A (en) * | 1944-12-19 | High-frequency thermocouple | ||
| US2565900A (en) * | 1946-07-08 | 1951-08-28 | Sylvania Electric Prod | High-frequency dummy antenna and power indicator |
-
1974
- 1974-03-01 US US447175A patent/US3889268A/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2365207A (en) * | 1944-12-19 | High-frequency thermocouple | ||
| US2565900A (en) * | 1946-07-08 | 1951-08-28 | Sylvania Electric Prod | High-frequency dummy antenna and power indicator |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100248649A1 (en) * | 2009-03-30 | 2010-09-30 | White Douglas W | Antenna with integrated tuning detection elements |
| US8472904B2 (en) | 2009-03-30 | 2013-06-25 | The Charles Stark Draper Laboratory, Inc. | Antenna with integrated tuning detection elements |
| US20140347250A1 (en) * | 2013-05-27 | 2014-11-27 | Fujitsu Component Limited | Antenna apparatus |
| US9590295B2 (en) * | 2013-05-27 | 2017-03-07 | Fujitsu Component Limited | Antenna apparatus |
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