A High-performan Ce 2-to-1 8-ghz Sweeper in This Issue: the Dual Function Generator: a Source of a Wide Variety of Fest

This precise, compact microwave sweep oscillator is a signif icant contribution to its f ield. The latest microelectronic and YIG technology makes it possib/e. tT, Hn NEED FOR VERY BROADBAND swept I microwave sources is well established. Production testing of multi-octave devices requires a broad-band sweeper that is simple to operate. Automated test systems need a source that is programmable and can be phase locked. Broadband receiver testing often requires a compact unit for on-site swept tests. The broad area of microwave design calls for a general-purpose sweeper that offers precision performance and is simple to interface with related equipment and convenient to operate. The truly broadband source, a single oscillator capable of sweeping a frequency range such as 2 to 18 GHz in one uninterrupted sweep, is not presently available, but there are alternatives. The most direct method is to sequence several narrower-band sweepers by means of an external controller so the resulting sweep covers the desired range. Another approach, using one sweeper and several plug-in RF heads installed in a "head-holder", reduces circuit redundancy and simplifies operation by giving frequency control to a single sweeper, but the equipment is still physically large. A more compact scheme is to put the required oscil-lators in a single sweeper and sequence them internally , More compact yet is a single oscillator followed by a harmonic multiplier to produce the higher frequencies. A New Sweeper This last scheme is used in the new Model 86290A 2-Io-18-GHzRF Plug-In for the 8620A Sweep Oscilla-tor mainframe, making the combination the most compact broadband sweeper currently available (see Fig. 1). Designed to meet the requirements of all major sweeper applications, the 8620A/86290A provides more than *5 dBm of power, leveled to within +0,9 dB, in fast, continuous sweeps over the 2-to-1,8-GHz frequency range or any portion of this range [Fig. 2). Besides the 2-to-18-GHz band, the 86290A provides three narrower bands: 2-6.2,6-12.4, and L2-18 GHz. AII bands are selectable by means of a front-panel dial drum switch on the 86204 mainframe. In CW mode in any of the narrower bands, the output frequency is accurate within-r2OMHzand resolution is 100 kHz, specifications approaching those of the traditionally more precise signal generator. Sweeping over the widest band the frequency is accurate within-r80 MHz. Undesired harmonics are at least 25 dB and typically 30 dB below the desired output signal. The new sweeper weighs just 15 kg (33Ib), so …