This article presents a novel 2.45 GHz compact double comb-shaped slotted rectenna system that is intended to capture RF energy from the environment. The suggested rectenna incorporates two comb-like structures onto a square patch antenna, and the voltage doubler rectifier circuit has a small footprint, measuring 48x31x1.5mm3. The suggested design includes semi-circular slots at the patch center for improved bandwidth and impedance matching, and double comb structures to increase antenna return loss characteristics and radiation performance. The Rectenna prototype was built on a 1.5 mm thick, cost-effective FR-4 substrate to assess the performance of the system. Both a modelling tool and a measurement are used to analyze the harvesting capacity of the rectenna.  The analysis findings show a return loss (S11) of -10 dB across a fractional bandwidth of 17.14% between 2.3 GHz and 2.48 GHz. The rectifier circuit provides a maximum energy conversion efficiency of 83% at 2.45 GHz and output voltage of 2.2V with a 2 KO load resistance. The analysis of the experiment's data shows that the suggested rectenna can efficiently gather RF energy from the surrounding environment.  

In this paper, a systematic approach to reduce size of circular patch antenna is demonstrated. A detailed analysis of electrical behavior of antenna is presented for different slots and slit to determine path to attain size reduction of the antenna. Final size of the antenna is reduced by combining two circular sector slots of length 90⁰, circular slot of radius 25 mm and a diametric slit of length 15 mm to 0.52 ?o x 0.52 ?o x 0.029 ?o mm³. The antenna is designed to cover UHF RFID application band. The antenna bandwidth obtained is 41 MHz and gain of the antenna is 7.3 dBi at 866 MHz. The proposed work is compared with other existing work and is observed that the proposed antenna not only is compact in size but has highest gain. All the measured results are in close agreement with the simulated results and is a very suitable candidate for making high gain compact array antenna. 

In this paper, a third order tunable bandpass filter using substrate integrated wave guide (SIW) topology is presented. A cross shaped slot is etched on the top surface of the SIW cavity structure to implement the passband from 4.6 -5.1 GHz. The novel cross shaped slot is designed smartly on the top of the SIW cavity to achieve 3rd order bandpass filter characteristics without increasing the dimension of the cavity. By placing the cross shaped slot at an offset of 1.0 mm from the center of the cavity structure, a transmission zero is created on the upper side of the passband. Presence of transmission zero increases the selectivity of the propose structure and accomplish an upper wide stop band characteristic. Two varactor diodes a reloaded using the radial stubs on the top plane to produce tunable passband characteristics. The centre frequency of the passband is tuned over a band width of 600 MHz by properly applying the bias voltage. An equivalent circuit is presented in order to understand the working of the filter. To confirm the simulated results, the proposed filter is fabricated and measured. The simulated results area greed well with the measured results.

This research paper presents a compact dual-band polyester-based wearable bandpass microstrip filter using stepped impedance resonator. In the proposed wearable filter, pass band of 1.85 GHz to 2.66 GHz is useful for ISM band and 3.74 GHz to 7.42 GHz is appropriate to Wi-Fi, WLAN and Wi-Max frequency band applications respectively. In this filter, insertion loss of 0.147 dB and return loss of 32.6 dB at 2.38 GHz insertion loss of 0.469 dB and return loss of 32.3 dB at 4.54 GHz with fractional bandwidth of 34% and 81% is respectively achieved. The proposed wearable filter is fabricated using polyester cloth substrate and self-adhesive copper tape. The Agilent vector network analyzer is used to test the fabricated polyester filter. Good agreement is obtained between the simulated as well as measured insertion loss and return loss of the proposed wearable filter. Equivalent circuit and SAR analysis of this filter is also presented in this paper. Novelty of this research paper is fabrication of high bandwidth dual band wearable filter that can be integrated with wearable antenna to be a wearable Filtenna. Modified equivalent circuit of SIR is prepared and validated. Simulated and measured results are found to be in good agreement.

In this paper, a compact size, high gain, narrow beam array antenna is proposed for RFID application. A suitable compact size antenna with a gain of 7 dBi is designed as basic element for the array. This base antenna is designed using three slots. Unlike other works, all the three slots are different in shape. Electrical equivalent for this antenna is also proposed to understand antenna working. The same compact antenna is used as basic element to design a 2 x 2 antenna array. A 4:1 feeding network is designed and electrical equivalent of the same is proposed to show power division among the four-radiating patches. Overall size of antenna array is 1.04 ??0 x 1.04 ??0 x 0.029 ??0 mm3. Array’s radiation beamwidth is 530 and gain of the antenna array is 10.3 dBi. All the measured results are in good agreement with simulated results. The proposed work is compared with other existing works and is found to be highly compact with excellent gain for the same size.