We have investigated the possibility of building a Dicke radiometer that is inexpensive, small-sized, stable, high sensitivity and consists of readily available microwave components. The selected frequency band is at 3-4 GHz and can be used for breast cancer detection, with sufficient spatial resolution. We have found microwave components that are small (< 5 mm x 5 mm) and provide sufficient sensitivity. We have built two different Dicke radiometers: One is of conventional design with Dicke switch at front end to select antenna or noise rererence and the other with a low noise amplifier before the Dicke Switch. We have tested this concept with simulations and built prototypes. The two designs provide a gain of approximately 50 dB, and bandwidth of about 500 MHz. One of the designs has a stability n > 1 and the other design provide instability (i < 1 for a part of the pass band. The prototypes are tested for sensitivity after calibration in two different known temperature waterbaths. The results show that the design with the low noise amplifier before the Dicke switch has 36% higher sensitivity than the other design with Dicke switch in front.
展开▼
机译：我们研究了构建价格低廉，体积小，稳定，灵敏度高并且由易于获得的微波组件组成的Dicke辐射计的可能性。所选频段为3-4 GHz，可用于乳腺癌检测，具有足够的空间分辨率。我们发现微波组件很小（<5 mm x 5 mm），并具有足够的灵敏度。我们构建了两种不同的Dicke辐射计：一种是常规设计，前端有Dicke开关来选择天线或噪声系数，另一种是在Dicke Switch之前使用低噪声放大器。我们已经通过仿真测试了这个概念，并构建了原型。两种设计提供约50 dB的增益和约500 MHz的带宽。其中一种设计的稳定性为n> 1，而另一种设计则提供了不稳定性（对于一部分通带，i <1。在经过两次不同的已知温度水浴校准后，对原型进行了灵敏度测试。结果表明，该设计具有Dicke开关之前的低噪声放大器的灵敏度比前面带有Dicke开关的其他设计高36％。
展开▼
