 Deployable double-membrane surface antenna |
| OF THE PREFERRED EMBODIMENT: Referring to FIG. 1, a planar array antenna system 1 is shown mounted ... |
|
| Pin retention system |
| OF THE ILLUSTRATED EMBODIMENTS In FIG. 1, the coupling pin comprises a generally cylindrical body ... |
|
| Epitaxial thin superconducting thallium-based copper oxide layers |
| What is claimed is: 1. A superconducting article comprising an oriented, epitaxial superconducting ... |
|
| Molded patch antenna having an embedded connector and method therefor |
| Thus, what is claimed is: 1. A method for forming a molded patch antenna having an embedded ... |
|
| Loop antenna for radiating circularly polarized waves |
| I claim: 1. A loop antenna for radiating a circularly polarized wave comprising: a ground plane; a C... |
|
| Electromagnetic antenna collimator |
| It is accordingly a primary object of the invention to provide an antenna construction useful for ... |
|
| Radome wall design having broadband and mm-wave characteristics |
| These and other objects of the invention are accomplished by a multi-layer radome construction ... |
|
| Doppler radar |
| There is claimed: 1. Doppler radar for measuring objects, comprising a first and a second ... |
|
| Variable gain power amplifier |
| In accordance with the amplifier of the present invention, the above-described and other ... |
|
|
Automatic antenna tuner for low-cost mobile radio
| Details |
Inventors: Belcher, Donald K.; Bailey, David C.;
Assignee: Flash Comm, Inc. (Melbourne, FL)
Primary Examiner: Hajer; Donald T.
Assistant Examiner: Ho; Tan
Attorney, Agent or Firm: Vinson & Elkins L.L.P.
An automatic antenna tuner which conjugately matches the impedance of an electrically small antenna to the impedance of a transmit amplifier output stage by using a pi-type impedance matching network with adjustable capacitive circuit components which are preferably implemented using a low cost escapement mechanism. During an initial set up tuning procedure, a resistive Wheatstone bridge detector is disposed between the output of the power amplifier and the input to the pi network, to feedback a measure a degree of match of the pi network to a controller. The capacitive elements in the legs of the pi network are then electromechanically adjusted under the operator of the controller until an optimum setting is found. These initial impedance values are determined for each frequency in an operating range and then stored in a non-volatile memory. As a second step in the tuning procedure, a fine adjustment is made to the stored optimum impedance values just prior to transmission, to accommodate changing environmental conditions and the like. |
|
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT FIG.
1 illustrates an automatic antenna tuner 10 according to the invention, which includes an input selector circuit 20, a pi-type impedance matching network 30 consisting of a pair of adjustable shunt capacitances 35 and 36 and series inductance 37, and a controller 50.
The tuner 10 finds application in a specific type of radio communication system in which mobile and/or portable field units transmit in the high frequency (HF) radio band.
In such an application, a signal, f, is received by the controller 50 to tune to a particular frequency.
The signal f may be received from network operation control center via a control channel over a radio link operating at HF or in other radio bands.
The remote unit is then expected to tune to the commanded frequency and to begin transmission within several seconds.
To accomplish this, the antenna tuner 10 preferably makes use of a pulsed escapement mechanism to implement the adjustable capacitances 35 and 36.
In a manner that is described in detail below, the escapement mechanism provides for automatic adjustment of the capacitances 35 and 36 via the controller 50.
The series inductance 37 also be adjustable, if implemented as a number of physical inductors 37-1, 37-2, .
.
.
,37-n which can be selectively switched into the pi network 30 by switches 38 and 39.
The switches 38 and 39 may be ganged together.
More particularly, the tuner 10 conjugately matches impedance the output impedance of a transmitter power amplifier 12 so that a maximum possible amount of power is transmitted to an antenna 14, despite the fact that the antenna 14 is electrically small.
This is done by adjusting the impedances in the pi network, such as by operating the adjustable shunt capacitive elements 35 and 36, and/or switching in various values for the series inductance 37.
It should be noted that the controller 50 adjusts these impedances 35, 36, and/or 37 by communicating with the adjustable capacitances 35 and 36, and the switches 38 and 39 over any suitable control interface such as a control bus 29
|
|
MEMS 
