WIDEBAND IMAGE TERMINATED MIXER

• US 3,681,697 A
• Filed: 12/31/1969
• Issued: 08/01/1972
• Est. Priority Date: 12/31/1969
• Status: Expired due to Term

• Current Assignee: John E. Moroney
• Original Assignee: John E. Moroney
• Inventors: Moroney, John E.
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US04/889,515
• Time in Patent Office: 944 Days
• Field of Search: 325/431,434,435,437,445,446,388,432,433,449 332/44,48
• US Class Current: 455/313
• CPC Class Codes: H03D 7/1408 with diodes
• CPC Class Codes: H03D 7/165 at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature combined with amplitude demodulation H03D1/2245, combined with angle demodulation H03D3/007; N-path filters H03H19/002
• CPC Class Codes: H03D 7/18 Modifications of frequency-changers for eliminating image frequencies H03D7/16 takes precedence
• CPC Class Codes: H03D 9/0608 by means of diodes

Abstract

Described is a wideband image terminated mixer of the type in which an input signal is split into two parts which are fed to separate mixers supplied with local oscillations from a single oscillator. After mixing, the resultant intermediate frequency signals at the outputs of the mixers are combined. The invention is characterized in that the image frequency signals returning from the mixers in the signal paths are summed at an image termination having a reactance such that the incident image frequency signals reflect back to the mixer where mixing with the local oscillator frequency converts at least portion of the image energy to the intermediate frequency. This reduces insertion losses and allows the image to be terminated over at least a 10 percent radio frequency bandwidth using a standard intermediate frequency such as 30 megahertz.

Claims

1. A wideband image enhancement mixer system comprising, microwave coupling means having at least three ports, one of said ports of said coupling means serving as an input signal port and two of said ports serving as output signal ports for dividing an incoming signal between two signal paths, microwave transmission lines connecting said two output ports, respectively, with two balanced mixers, a local oscillator, a first 90* hybrid coupler having one of its ports connected to the output of said oscillator and having two ports serving as outputs connected respectively, to each of said mixers and a fourth port connected to a matched load impedance, a second 90* hybrid microwave junction having two ports connected, respectively, to the outputs of said mixers and two other ports, one of which is connected to a matched load and the other of which constitutes a signal output, whereby the resultant intermediate frequency signals at the outputs of said mixers are combined and the image frequency signals returning from said mixers are summed image termination and reflected back to said mixers to convert at least a portion of the image frequency signal energy to intermediate frequency energy.

2. The combination as set forth in claim 1 in which said coupling means is a 180* microwave hybrid junction having a fourth port connected to a terminating impedance.

3. The combination as set forth in claim 1 in which said first means is a power divider.