JPH02206903A - harmonic mixer - Google Patents

Abstract

PURPOSE:To reduce the transmission loss and to improve the conversion loss characteristic by operating the harmonic mixer at a frequency being a half of a local oscillating(Lo) signal frequency and inputting a high frequency (RF) signal through a waveguide. CONSTITUTION:An RF signal is inputted to two mixer diodes connecting to a center conductor of a coplaner line 14 in opposite polarities to each other through a waveguide 6 from the rear side of the coplaner line 14 and an Lo signal inputted from one end of the coplaner line 14 are inputted to the mixer diode 2 and they are mixed. In this case, a bipolar current flows to the mixer diodes 2 connecting to a center conductor of the coplaner line 14 in opposite polarities to each other resulting from the input of the Lo signal and the period is a half of that of the Lo signal, and the mixer is acted at the frequency twice that of the Lo frequency signal. Thus, the transmission loss of an RF transmission line is reduced and the conversion loss characteristic is improved.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is for frequency conversion used in microwave/millimeter wave band wireless communication equipment, etc.
) This relates to a harmonic mixer that mixes a frequency twice the frequency and an RF input frequency to obtain an intermediate frequency signal.

BACKGROUND OF THE INVENTION Conventionally, harmonic mixers in microwave and millimeter wave bands have been manufactured using waveguides or using microstrip lines. However, as the frequency increases, the waveguide type becomes smaller in shape and requires high machining accuracy, making it very expensive. In comparison, those using microstrip lines can be made at low cost without any machining, but the transmission loss of microstrip lines increases significantly at the upper limit of the microwave band. In the case of a mixer for a down converter in this frequency band, when the RF multiplied signal is input to the mixer diode through a microstrip line, the loss in the microstrip line up to the mixer diode greatly affects the conversion loss of the mixer.

Problems to be Solved by the Invention As mentioned above, harmonic mixers using conventional microstrip lines have been able to achieve lower costs, but
There was a problem in that the characteristics deteriorated due to transmission loss of the RF transmission line.

Therefore, an object of the present invention is to reduce the transmission loss of the RF transmission line as described above and improve the characteristics.

Means for Solving the Problems In order to achieve the above object, the technical solution of the present invention is to use a waveguide for high frequency (RF) input, and improve the RF signal transmission loss, and the MIC part is Basically, it consists of a microstrip line, and the RF multiplied signal input to the mixer diode uses a part of the microstrip line as a coplanar line, and the RF multiplied signal input is transmitted through a waveguide from the removed back conductor part. However, it is configured to be input to a mixer diode connected with opposite polarity to the center conductor of the coplanar line on the surface, and an intermediate frequency (IF) signal is output by mixing the frequency of the Lo multiplied signal and the RF multiplied signal. The configuration is as follows.

Function The present invention uses the RF multiplication signal waveguide of a harmonic mixer to input from the back side of the coplanar line to two mixer diodes connected with opposite polarities to the center conductor of the coplanar line, and input from one end of the coplanar line. The Lo-multiplied signal is input to the mixer diode and mixed. At this time L
o times signal, a current of both positive and negative polarity flows through the mixer diode connected with opposite polarity to the center conductor of the coplanar line, the period is 1/2 of the Lo input frequency, and it operates at a frequency twice the Lo frequency do. Therefore, since the RF multiplier signal is handled using a waveguide, transmission loss can be extremely reduced, and a mixer with low conversion loss can be realized.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIG.

FIG. 1 is an exploded configuration diagram showing an embodiment of a harmonic mixer according to the present invention.

In FIG. 1, 1 is a dielectric substrate, 2 is a mixer diode provided on the dielectric substrate 1, and 3 is an LPF (low pass filter) formed on the dielectric substrate 1 by a microstrip line. pattern, 5 is the same capacitor, 6 is the RF terminal waveguide, 7 is the LO terminal, 8 is the IF terminal, 9 is the RF short block, 10 is R
A dielectric sheet is attached to one end surface of the F short block 9, 11 is a DC bias terminal, 12 is a housing, 13 is an isolated ground conductor formed on the dielectric substrate 1, and 14 is a coplanar line.

In FIG. 1, as an example, the operation will be described when the device is operated as a down mixer. First, the RF multiplied signal input from the RF terminal waveguide 6 is transferred from the back side of the coplanar line provided on the dielectric substrate 1 to the front side through the dielectric substrate 1 by removing the back conductor only at the opening of the waveguide. It is input to mixer diode 2 on the installed coplanar line.

Two mixer diodes 2 are connected to the center conductor of the coplanar line 14 with opposite polarities. mixer diode 2
The structure is such that a DC bias can be applied from the DC bias terminal 11, and the first mixer diode 2 is connected to the center conductor from the DC bias terminal 11, and the second mixer diode 2 is connected from the center conductor to the ground pattern. The ground pattern to which the second mixer diode 2 is connected is connected to the back ground conductor 13 by through-hole processing or the like. The RF short block 9 is used for RF signal matching, and the dielectric sheet 10 is connected to the part that contacts the DC bias terminal 11 side, and the mixer diode 2 on the DC bias terminal side is connected to the high frequency signal. is grounded. In terms of high frequency, the tab mixer diode 2 is grounded with the opposite polarity from the center conductor of the coplanar line 14. However, the RF multiplied signal input from the waveguide 6 of the RF terminal, the first mixer diode 2 attached to the center conductor of the coplanar line 14 from the DC bias terminal 11 side, and the center conductor of the coplanar line 14 are connected to the ground pattern. The second mixer diode 2 is connected in series on the eight surfaces of the waveguide, and the RF multiplied signal is input to the two mixer diodes 2 in the same phase. Therefore, the Lo multiplied signal input from the Lo terminal 7, the Lo signal on the dielectric substrate 1
The signal is transmitted from the terminal 7 to the coplanar line 14 via the DC cut pattern 4 composed of parallel coupled lines. As mentioned above, the two mixer diodes 2 attached to the center conductor of the coplanar line 14 are grounded with opposite polarity in terms of high frequency, and the positive and negative signals of the υ and Lo multiplied signals are connected to the mixer diodes every 1/2 period. 2, where the RF signal is mixed. The mixing output is the coplanar line 1 into which the Lo times signal is input.
I
It is output from the F terminal 8 and the IF terminal connector 8a.

FIG. 2 shows the mounting structure of the mixer diode 2, which is the main part of the component shown in FIG.

As shown in FIG. 2, two mixer diodes 2 are arranged in series on the coplanar line 14, and
between the center conductor and the ground conductor.

A current, that is, a positive and negative rectified current, flows in the directions of LA and LB through the Lo-multiplying signal mixer diode 2 input from one side of the coplanar line 14, and its period is as follows.

It is 1/2 of the signal, and operates at twice the frequency of the Lo times signal. In addition, the RF multiplied signal is input from the back side of the coplanar line 14, and a high frequency current flows through the mixer diode 2 in the directions of RA and RE through the dielectric substrate 1 on the E side of the waveguide.
It is mixed with the Lo signal currents LA and LB to obtain an IF ratio output.

When attaching the dielectric substrate 1 shown in FIG. 1 to the casing 12, it is possible to separate it from the MIC section such as the mixer diode by adhering it to the back ground conductor with a conductive adhesive.
Even if the terminal waveguide is directly connected to an antenna or the like, a waterproof structure can be easily achieved.

Also, since the RF terminal part is a waveguide, the RF signal propagation loss is
A harmonic mixer with small size and good conversion characteristics can be realized. Although we will explain the down mixer here, it goes without saying that it can also operate as an up converter.

Effects of the Invention As described above, the present invention operates at 1/2 the LO signal frequency and inputs it through an RF multiplied signal waveguide, thereby reducing the transmission loss between the transmission lines and improving the conversion loss characteristics. A good harmonic mixer can be realized. In addition, since the RF multiplied signal is input from the back side of the dielectric substrate, the MIC part including the mixer diode and the waveguide part can be easily separated, so the MIC part can be made waterproof. big.

[Brief explanation of the drawing]

Fig. 1 is an exploded structural diagram of a monic mixer showing an embodiment of the present invention, and Fig. 2 (a) and (b) show the structure of the mixer diode mounting part, which is the main part of Fig. 1. They are a plan view and a sectional view. 1... Dielectric substrate, 2... Mixer diode, 3...
...LPF, 4...DC cut pattern, 5...Capacitor, 6...RF terminal waveguide, 7...Lo terminal, 8...■F terminal, 9...RF short block ,
DESCRIPTION OF SYMBOLS 10... Dielectric sheet, 11... DC cut pattern, 12... Housing, 13... Back ground conductor, 14...
・Coplena line. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (2)

[Claims] (1) Two mixer diodes are installed on a coplanar line provided on a dielectric substrate parallel to the H-plane of the waveguide, and the two mixer diodes are attached to the center conductor of the coplanar line with opposite polarity. The local oscillation frequency signal is inputted from one end of the coplanar line through a microstrip line, and the other end of the coplanar line is configured with a microstrip line. An intermediate frequency output is taken out through a low-pass filter, and a high frequency input signal is inputted through the waveguide, inputted into the mixer diode from the back side of the coplanar line, and mixed with a double wave of the local oscillation signal, A harmonic mixer characterized by obtaining an intermediate frequency signal. (2) The back conductor of the dielectric substrate with the mixer diode attached is removed only from the high frequency input terminal portion, the front surface is made into a coplanar line, and the back conductor portion and the casing having the high frequency input terminal waveguide are glued together. 2. The harmonic mixer according to claim 1, wherein the inside of the wave tube and the circuit portion are separated.